@article {Roman2023a, title = {Current Perspectives on Securing Critical Infrastructures{\textquoteright} Supply Chains}, journal = {IEEE Security \& Privacy}, year = {In Press}, publisher = {IEEE}, issn = {1540-7993}, author = {Rodrigo Roman and Cristina Alcaraz and Javier Lopez and Kouichi Sakurai} } @inproceedings {Garcia2023, title = {MAS para la convergencia de opiniones y detecci{\'o}n de anomal{\'\i}as en sistemas ciberf{\'\i}sicos distribuidos}, booktitle = {VIII Jornadas Nacionales de Investigaci{\'o}n en Ciberseguridad (JNIC)}, year = {In Press}, month = {06/2023}, address = {Vigo}, keywords = {Detecci{\'o}n avanzada, din{\'a}micas de opiniones, machine-learning, sistemas ciberf{\'\i}sicos, Sistemas multi-agente}, author = {Alberto Garcia and Cristina Alcaraz and Javier Lopez} } @article {Alcaraz2023b, title = {OCPP in the spotlight: threats and countermeasures for electric vehicle charging infrastructures 4.0}, journal = {International Journal of Information Security}, year = {In Press}, publisher = {Springer}, address = {Springer Verlag}, abstract = {

Undoubtedly, Industry 4.0 in the energy sector improves the conditions for automation, generation and distribution of energy, increasing the rate of electric vehicle manufacturing in recent years. As a result, more grid-connected charging infrastructures are being installed, whose charging stations (CSs) can follow standardized architectures, such as the one proposed by the open charge point protocol (OCPP). The most recent version of this protocol is v.2.0.1, which includes new security measures at device and communication level to cover those security issues identified in previous versions. Therefore, this paper analyzes OCPP-v2.0.1 to determine whether the new functions may still be susceptible to specific cyber and physical threats, and especially when CSs may be connected to microgrids. To formalize the study, we first adapted the well-known threat analysis methodology, STRIDE, to identify and classify threats in terms of control and energy, and subsequently we combine it with DREAD for risk assessment. The analyses indicate that, although OCPP-v2.0.1 has evolved, potential security risks still remain, requiring greater protection in the future.

}, issn = {1615-5262}, doi = {https://doi.org/10.1007/s10207-023-00698-8}, url = {https://link.springer.com/article/10.1007/s10207-023-00698-8}, author = {Cristina Alcaraz and Jesus Cumplido and Alicia Trivi{\~n}o} } @article {Alcaraz2023a, title = {Protecting Digital Twin Networks for 6G-enabled Industry 5.0 Ecosystems}, journal = {IEEE Network Magazine}, year = {In Press}, publisher = {IEEE}, issn = {0890-8044}, author = {Cristina Alcaraz and Javier Lopez} } @inproceedings {morales2023metacom, title = {Integration of MPC into Besu through an extended private transaction model}, booktitle = {IEEE International Conference on Metaverse Computing, Networking and Applications}, year = {2023}, month = {06/2023}, address = {Kyoto, Japan}, abstract = {In the last few years we have seen many different approaches to incorporate privacy features to blockchains. In the area of cryptocurrencies that would normally mean protecting the identity of the owner of some funds, but there are other applications where privacy is even more important, especially in permissioned blockchains. Permissioned blockchain platforms, such as Hyperledger Besu or Hyperledger Fabric, already include the concept of private transactions, which essentially defines a sub-group of the blockchain where their participants share some private data. We want to go one step ahead and propose an extended model for private transactions where the different participants can have a separated view of the same transaction, allowing the integration of Multi-party Computation protocols in the blockchain. Our work extends Hyperledger Besu{\textquoteright}s design for private transactions, offering better security properties and a finer grain customization. We cover two specific MPC examples, Private Set Intersection and Byzantine Fault-Tolerant Random Number Generation, and propose a mechanism to run them using smart contract interfaces. }, keywords = {blockchain, hyperledger besu, privacy, secure multi-party computation}, author = {Daniel Morales and Isaac Agudo and Javier Lopez} } @article {morales2023psi, title = {Private set intersection: A systematic literature review}, journal = {Computer Science Review}, volume = {49}, number = {100567}, year = {2023}, month = {05/2023}, publisher = {Elsevier}, type = {Review}, address = {ScienceDirect}, abstract = {Secure Multi-party Computation (SMPC) is a family of protocols which allow some parties to compute a function on their private inputs, obtaining the output at the end and nothing more. In this work, we focus on a particular SMPC problem named Private Set Intersection (PSI). The challenge in PSI is how two or more parties can compute the intersection of their private input sets, while the elements that are not in the intersection remain private. This problem has attracted the attention of many researchers because of its wide variety of applications, contributing to the proliferation of many different approaches. Despite that, current PSI protocols still require heavy cryptographic assumptions that may be unrealistic in some scenarios. In this paper, we perform a Systematic Literature Review of PSI solutions, with the objective of analyzing the main scenarios where PSI has been studied and giving the reader a general taxonomy of the problem together with a general understanding of the most common tools used to solve it. We also analyze the performance using different metrics, trying to determine if PSI is mature enough to be used in realistic scenarios, identifying the pros and cons of each protocol and the remaining open problems.}, keywords = {privacy, Private set intersection, Secure Multiparty computation, security}, issn = {1574-0137}, doi = {https://doi.org/10.1016/j.cosrev.2023.100567}, url = {https://www.sciencedirect.com/science/article/pii/S1574013723000345}, author = {Daniel Morales and Isaac Agudo and Javier Lopez} } @article {Syrmakesis2022, title = {Classifying resilience approaches for protecting smart grids against cyber threats}, journal = {International Journal of Information Security}, volume = {21}, year = {2022}, month = {05/2022}, pages = {1189{\textendash}1210}, publisher = {Springer}, address = {Springer Verlag}, abstract = {

Smart grids (SG) draw the attention of cyber attackers due to their vulnerabilities, which are caused by the usage of heterogeneous communication technologies and their distributed nature. While preventing or detecting cyber attacks is a well-studied field of research, making SG more resilient against such threats is a challenging task. This paper provides a classification of the proposed cyber resilience methods against cyber attacks for SG. This classification includes a set of studies that propose cyber-resilient approaches to protect SG and related cyber-physical systems against unforeseen anomalies or deliberate attacks. Each study is briefly analyzed and is associated with the proper cyber resilience technique which is given by the National Institute of Standards and Technology in the Special Publication 800-160. These techniques are also linked to the different states of the typical resilience curve. Consequently, this paper highlights the most critical challenges for achieving cyber resilience, reveals significant cyber resilience aspects that have not been sufficiently considered yet and, finally, proposes scientific areas that should be further researched in order to enhance the cyber resilience of SG.

}, keywords = {Cyber threats, cyber-physical systems, resilience, Smart grids}, issn = {1615-5262}, doi = {https://doi.org/10.1007/s10207-022-00594-7}, url = {https://link.springer.com/content/pdf/10.1007/s10207-022-00594-7.pdf}, author = {Andrew D. Syrmakesis and Cristina Alcaraz and Nikos D. Hatziargyriou~} } @inproceedings {Alcaraz2022c, title = {Collaborative anomaly detection system for charging stations}, booktitle = {The 27th European Symposium on Research in Computer Security (ESORICS 2022)}, volume = {13555}, year = {2022}, month = {09/2022}, pages = {716{\textendash}736}, publisher = {Springer, Cham}, organization = {Springer, Cham}, abstract = {

In recent years, the deployment of charging infrastructures has been increasing exponentially due to the high energy demand of electric vehicles, forming complex charging networks. These networks pave the way for the emergence of new unknown threats in both the energy and transportation sectors. Economic damages and energy theft are the most frequent risks in these environments. Thus, this paper aims to present a solution capable of accurately detecting unforeseen events and possible fraud threats that arise during charging sessions at charging stations through the current capabilities of the Machine Learning (ML) algorithms. However, these algorithms have the drawback of not fitting well in large networks and generating a high number of false positives and negatives, mainly due to the mismatch with the distribution of data over time. For that reason, a Collaborative Anomaly Detection System for Charging Stations (here referred to as CADS4CS) is proposed as an optimization measure. CADS4CS has a central analysis unit that coordinates a group of independent anomaly detection systems to provide greater accuracy using a voting algorithm. In addition, CADS4CS has the feature of continuously retraining ML models in a collaborative manner to ensure that they are adjusted to the distribution of the data. To validate the approach, different use cases and practical studies are addressed to demonstrate the effectiveness and efficiency of the solution.

}, keywords = {Charging station, Collaborative anomaly detection, Machine Learning, Voting system}, doi = {https://doi.org/10.1007/978-3-031-17146-8_35}, author = {Jesus Cumplido and Cristina Alcaraz and Javier Lopez} } @inproceedings {1990, title = {Configuration vulnerability in SNORT for Windows operating systems}, booktitle = {2022 IEEE International Conference on Cyber Security and Resilience (IEEE CSR)}, year = {2022}, month = {08/2022}, pages = {82-89}, publisher = {IEEE}, organization = {IEEE}, address = {https://www.ieee-csr.org}, abstract = {

Cyber-attacks against Industrial Control Systems (ICS) can lead to catastrophic events which can be prevented by the use of security measures such as the Intrusion Prevention Systems (IPS). In this work we experimentally demonstrate how to exploit the configuration vulnerabilities of SNORT one of the most adopted IPSs to significantly degrade the effectiveness of the IPS and consequently allowing successful cyber-attacks. We illustrate how to design a batch script able to retrieve and modify the configuration files of SNORT in order to disable its ability to detect and block Denial of Service (DoS) and ARP poisoning-based Man-In-The-Middle (MITM) attacks against a Programmable Logic Controller (PLC) in an ICS network. Experimental tests performed on a water distribution testbed show that, despite the presence of IPS, the DoS and ARP spoofed packets reach the destination causing respectively the disconnection of the PLC from the ICS network and the modification of packets payload.

}, isbn = {978-1-6654-9952-1}, doi = {https://doi.org/10.1109/CSR54599.2022.9850309}, url = {https://ieeexplore.ieee.org/document/9850309}, author = {Luca Faramondi and Marta Grassi and Simone Guarino and Roberto Setola and Cristina Alcaraz} } @article {Alcaraz2022b, title = {Digital Twin: A Comprehensive Survey of Security Threats}, journal = {IEEE Communications Surveys \& Tutorials}, volume = {24}, number = {thirdquarter 2022}, year = {2022}, month = {04/2022}, pages = {1475 - 1503}, publisher = {IEEE}, type = {Survey}, address = {IEEE }, abstract = {

Industry 4.0 is having an increasingly positive impact on the value chain by modernizing and optimizing the production and distribution processes. In this streamline, the digital twin (DT) is one of the most cutting-edge technologies of Industry 4.0, providing simulation capabilities to forecast, optimize and estimate states and configurations. In turn, these technological capabilities are encouraging industrial stakeholders to invest in the new paradigm, though an increased focus on the risks involved is really needed. More precisely, the deployment of a DT is based on the composition of technologies such as cyber-physical systems, the Industrial Internet of Things, edge computing, virtualization infrastructures, artificial intelligence and big data. However, the confluence of all these technologies and the implicit interaction with the physical counterpart of the DT in the real world generate multiple security threats that have not yet been sufficiently studied. In that context, this paper analyzes the current state of the DT paradigm and classifies the potential threats associated with it, taking into consideration its functionality layers and the operational requirements in order to achieve a more complete and useful classification. We also provide a preliminary set of security recommendations and approaches that can help to ensure the appropriate and trustworthy use of a DT.

}, keywords = {Cybersecurity, Digital Twin, Industry 4.0}, issn = {1553-877X}, doi = {https://doi.org/10.1109/COMST.2022.3171465}, url = {https://ieeexplore.ieee.org/document/9765576}, author = {Cristina Alcaraz and Javier Lopez} } @inproceedings {1989, title = {Implicaciones de seguridad en MAS Desplegados en Infraestructuras de Carga basadas en OCPP}, booktitle = {VII Jornadas Nacionales en Investigaci{\'o}n en Ciberseguridad (JNIC 2022)}, year = {2022}, month = {06/2022}, pages = {172-179}, abstract = {

El inter{\'e}s actual por desplegar infraestructuras de carga de veh{\'\i}culos el{\'e}ctricos para el ahorro energ{\'e}tico y la sostenibilidad es cada vez m{\'a}s palpable, lo que llama la atenci{\'o}n a muchas comunidades, especialmente a la cient{\'\i}fica, para explorar, entre otras cosas, la influencia de las nuevas tecnolog{\'\i}as de informaci{\'o}n en los procesos operacionales. Teniendo en cuenta este escenario, este art{\'\i}culo, por tanto, analiza c{\'o}mo el uso de los sistemas de multi-agente pueden beneficiar las tareas de monitorizaci{\'o}n, mantenimiento y de seguridad, y propone una arquitectura espec{\'\i}fica en base a los actores especificados en el protocolo OCPP (Open Charge Point Protocol). Esta arquitectura constituye la base para analizar los diversos tipos de amenazas que agentes software pueden sufrir, clasific{\'a}ndolas de acuerdo a las caracter{\'\i}sticas funcionales e interacciones con los diversos elementos de la infraestructura. Esta agrupaci{\'o}n y el conjunto de ataques abordados est{\'a}n basados en el SP-800-19 definido por el National Institute of Standards and Technology, y formalizados siguiendo la metodolog{\'\i}a de {\'a}rboles de ataque. El estudio revela la importancia que tiene analizar los riesgos que esta tecnolog{\'\i}a puede traer a este escenario, proporcionando, adem{\'a}s, un conjunto de recomendaciones que sirvan de gu{\'\i}a para aplicaciones futuras.

}, isbn = {978-84-88734-13-6}, author = {Cristina Alcaraz and Alberto Garcia and Javier Lopez} } @article {ishak22, title = {Learning multi-party adversarial encryption and its application to secret sharing}, journal = {IEEE Access }, year = {2022}, publisher = {IEEE}, abstract = {

Neural networks based cryptography has seen a significant growth since the introduction of adversarial cryptography which makes use of Generative Adversarial Networks (GANs) to build neural networks that can learn encryption. The encryption has been proven weak at first but many follow up works have shown that the neural networks can be made to learn the One Time Pad (OTP) and produce perfectly secure ciphertexts. To the best of our knowledge, existing works only considered communications between two or three parties. In this paper, we show how multiple neural networks in an adversarial setup can remotely synchronize and establish a perfectly secure communication in the presence of different attackers eavesdropping their communication. As an application, we show how to build Secret Sharing Scheme based on this perfectly secure multi-party communication. The results show that it takes around 45,000 training steps for 4 neural networks to synchronize and reach equilibria. When reaching equilibria, all the neural networks are able to communicate between each other and the attackers are not able to break the ciphertexts exchanged between them.

}, keywords = {Cryptography, Encryption, Generative Adversarial Networks, Kernel, Mathematical models, Neural networks, Secret Sharing, Synchronization, Training}, issn = {2169-3536}, doi = {10.1109/ACCESS.2022.3223430}, url = {https://doi.org/10.1109/ACCESS.2022.3223430}, author = {Ishak Meraouche and Sabyasachi Dutta and Sraban Kumar Mohanty and Isaac Agudo and Kouichi Sakurai} } @inproceedings {morales2022cc, title = {Real-time Crowd Counting based on Wearable Ephemeral IDs}, booktitle = {19th International Conference on Security and Cryptography (SECRYPT 2022)}, year = {2022}, month = {07/2022}, pages = {249-260}, publisher = {Scitepress}, organization = {Scitepress}, address = {Lisbon}, abstract = {Crowd Counting is a very interesting problem aiming at counting people typically based on density averages and/or aerial images. This is very useful to prevent crowd crushes, especially on urban environments with high crowd density, or to count people in public demonstrations. In addition, in the last years, it has become of paramount importance for pandemic management. For those reasons, giving users automatic mechanisms to anticipate high risk situations is essential. In this work, we analyze ID-based Crowd Counting, and propose a real-time Crowd Counting system based on the Ephemeral ID broadcast by contact tracing applications on wearable devices. We also performed some simulations that show the accuracy of our system in different situations. }, keywords = {Crowd Counting, IDS, Pandemics, privacy, Secure Multiparty computation}, isbn = {978-989-758-590-6}, issn = {2184-7711}, doi = {10.5220/0011327200003283}, author = {Daniel Morales and Isaac Agudo and Javier Lopez} } @article {Flamini2022, title = {Towards Trustworthy Autonomous Systems: Taxonomies and Future Perspectives}, journal = {IEEE Transactions on Emerging Topics in Computing}, year = {2022}, publisher = {IEEE}, abstract = {

The class of Trustworthy Autonomous Systems (TAS) includes cyber-physical systems leveraging on self-x technologies that make them capable to learn, adapt to changes, and reason under uncertainties in possibly critical applications and evolving environments. In the last decade, there has been a growing interest in enabling artificial intelligence technologies, such as advanced machine learning, new threats, such as adversarial attacks, and certification challenges, due to the lack of sufficient explainability. However, in order to be trustworthy, those systems also need to be dependable, secure, and resilient according to well-established taxonomies, methodologies, and tools. Therefore, several aspects need to be addressed for TAS, ranging from proper taxonomic classification to the identification of research opportunities and challenges. Given such a context, in this paper address relevant taxonomies and research perspectives in the field of TAS. We start from basic definitions and move towards future perspectives, regulations, and emerging technologies supporting development and operation of TAS.

}, keywords = {Arti cial Intelligence, Cyber- Resilience, Cybersecurity, Dependability, Intelligent Systems, Trustworthy Autonomous Systems}, issn = {2168-6750}, doi = {https://doi.org/10.1109/TETC.2022.3227113}, url = {https://ieeexplore.ieee.org/abstract/document/9979717/authors$\#$authors}, author = {Francesco Flammini and Cristina Alcaraz and Emanuele Bellini and Stefano Marrone and Javier Lopez and Andrea Bondavalli} } @article {Agudo2020, title = {A Blockchain Approach for Decentralized V2X (D-V2X)}, journal = {IEEE Transactions on Vehicular Technology}, volume = {70}, number = {5}, year = {2021}, month = {05/2021}, pages = {4001 - 4010}, publisher = {IEEE}, abstract = {

New mobility paradigms have appeared in recent years, and everything suggests that some more are coming. This fact makes apparent the necessity of modernizing the road infrastructure, the signalling elements and the traffic management systems. Many initiatives have emerged around the term Intelligent Transport System (ITS) in order to define new scenarios and requirements for this kind of applications. We even have two main competing technologies for implementing Vehicular communication protocols (V2X), C-V2X and 802.11p, but neither of them is widely deployed yet.

One of the main barriers for the massive adoption of those technologies is governance. Current solutions rely on the use of a public key infrastructure that enables secure collaboration between the different entities in the V2X ecosystem, but given its global scope, managing such infrastructure requires reaching agreements between many parties, with conflicts of interest between automakers and telecommunication operators. As a result, there are plenty of use cases available and two mature communication technologies, but the complexity at the business layer is stopping the drivers from taking advantage of ITS applications.

Blockchain technologies are defining a new decentralized paradigm for most traditional applications, where smart contracts provide a straightforward mechanism for decentralized governance. In this work, we propose an approach for decentralized V2X (D-V2X) that does not require any trusted authority and can be implemented on top of any communication protocol. We also define a proof-of-concept technical architecture on top of a cheap and highly secure System-on-Chip (SoC) that could allow for massive adoption of D-V2X.\ 

}, issn = {0018-9545}, doi = {10.1109/TVT.2020.3046640}, author = {Isaac Agudo and Manuel Montenegro-G{\'o}mez and Javier Lopez} } @article {lopez2020, title = {Digital Twins for Intelligent Authorization in the B5G-enabled Smart Grid}, journal = {IEEE Wireless Communications}, volume = {28}, year = {2021}, month = {04/2021}, pages = {48-55}, publisher = {IEEE}, abstract = {

Beyond fifth generation (B5G) communication networks and computation paradigms in the edge are expected to be integrated into power grid infrastructures over the coming years. In this sense, AI technologies will play a fundamental role to efficiently manage dynamic information flows of future applications, which impacts the authorization policies applied in such a complex scenario. This article studies how digital twins can evolve their context awareness capabilities and simulation technologies to anticipate faults or to detect cyber-security issues in real time, and update access control policies accordingly. Our study analyzes the evolution of monitoring platforms and architecture decentralization, including the application of machine learning and blockchain technologies in the smart grid, toward the goal of implementing autonomous and self-learning agents in the medium and long term. We conclude this study with future challenges on applying digital twins to B5G-based smart grid deployments.

}, issn = {1536-1284}, doi = {https://doi.org/10.1109/MWC.001.2000336}, url = {https://ieeexplore.ieee.org/document/9430900}, author = {Javier Lopez and Juan E. Rubio and Cristina Alcaraz} } @incollection {1844, title = {Risk Assessment for IoT-Enabled Cyber-Physical Systems}, booktitle = {Advances in Core Computer Science-Based Technologies}, year = {2021}, pages = {157-173}, publisher = {Springer International Publishing}, organization = {Springer International Publishing}, address = {Cham}, abstract = {

Internet of Things (IoT) technologies have enabled Cyber-Physical Systems (CPS) to become fully interconnected. This connectivity however has radically changed their threat landscape. Existing risk assessment methodologies often fail to identify various attack paths that stem from the new connectivity/functionality features of IoT-enabled CPS. Even worse, due to their inherent characteristics, IoT systems are usually the weakest link in the security chain and thus many attacks utilize IoT technologies as their key enabler. In this paper we review risk assessment methodologies for IoT-enabled CPS. In addition, based on our previous work (Stellios et al. in IEEE Commun Surv Tutor 20:3453{\textendash}3495, 2018, [47]) on modeling IoT-enabled cyberattacks, we present a high-level risk assessment approach, specifically suited for IoT-enabled CPS. The mail goal is to enable an assessor to identify and assess\ non-obvious(indirect or subliminal) attack paths introduced by IoT technologies, that usually target mission critical components of an CPS.

}, keywords = {Critical Infrastructures, Cyber Physical Systems (CPS), Internet of Things (IoT), Risk assessment Attack paths}, isbn = {978-3-030-41196-1}, doi = {10.1007/978-3-030-41196-1_8}, url = {https://doi.org/10.1007/978-3-030-41196-1_8}, author = {Ioannis Stellios and Panayiotis Kotzanikolaou and Mihalis Psarakis and Cristina Alcaraz} } @incollection {Alcaraz2021d, title = {Situational Awareness for CPS}, booktitle = {Encyclopedia of Cryptography, Security and Privacy}, year = {2021}, month = {08/2021}, pages = {1--3}, publisher = {Springer Berlin Heidelberg}, organization = {Springer Berlin Heidelberg}, type = {Encyclopedia}, address = {Berlin, Heidelberg}, keywords = {Anomaly detection, Attack traceability, Prevention, Response, Visualization}, isbn = {978-3-642-27739-9}, doi = {10.1007/978-3-642-27739-9_1732-1}, url = {https://doi.org/10.1007/978-3-642-27739-9_1732-1}, author = {Cristina Alcaraz} } @article {Alcaraz2021a, title = {Stakeholder Perspectives and Requirements on Cybersecurity in Europe}, journal = {Journal of Information Security and Applications}, volume = {61}, number = {102916}, year = {2021}, month = {09/2021}, publisher = {Elsevier}, keywords = {Cybersecurity, Requirements, Roadmap, Stakeholder engagement. Research \& innovation}, issn = {2214-2126}, doi = {https://doi.org/10.1016/j.jisa.2021.102916}, url = {https://www.sciencedirect.com/science/article/pii/S2214212621001381}, author = {Simone Fischer-H{\"u}bner and Cristina Alcaraz and Afonso Ferreira and Carmen Fernandez-Gago and Javier Lopez and Evangelos Markatos and Lejla Islami and Mahdi Akil} } @article {Alcaraz2020a, title = {Blockchain-Assisted Access for Federated Smart Grid Domains: Coupling and Features}, journal = {Journal of Parallel and Distributed Computing}, volume = {144}, year = {2020}, month = {06/2020}, pages = {124-135}, publisher = {Elsevier}, issn = {0743-7315}, author = {Cristina Alcaraz and Juan E. Rubio and Javier Lopez} } @inproceedings {1846, title = {Distributed Detection of APTs: Consensus vs. Clustering}, booktitle = {25th European Symposium on Research in Computer Security (ESORICS 2020)}, volume = {12308}, year = {2020}, month = {09/2020}, pages = {174-192}, keywords = {Advanced Persistent Threat, clustering, consensus, distributed detection, Opinion Dynamics, Traceability}, isbn = {978-3-030-58951-6}, doi = {https://doi.org/10.1007/978-3-030-58951-6_9}, author = {Juan E. Rubio and Cristina Alcaraz and Ruben Rios and Rodrigo Roman and Javier Lopez} } @inproceedings {1840, title = {Game Theory-Based Approach for Defense against APTs}, booktitle = {18th International Conference on Applied Cryptography and Network Security (ACNS{\textquoteright}20)}, volume = {12147}, year = {2020}, month = {10/2020}, pages = {297-320}, publisher = {Springer}, organization = {Springer}, isbn = {978-3-030-57878-7}, doi = {https://doi.org/10.1007/978-3-030-57878-7_15}, author = {Juan E. Rubio and Cristina Alcaraz and Javier Lopez} } @inproceedings {1978, title = {Comunicaciones VoIP cifradas usando Intel SGX}, booktitle = {V Jornadas Nacionales de Investigaci{\'o}n en Ciberseguridad (JNIC)}, year = {2019}, month = {06/2019}, abstract = {

Cada d{\'\i}a es m{\'a}s frecuente encontrar servicios en internet gestionados desde plataformas online y con la expansi{\'o}n de la tecnolog{\'\i}a IoT, los smartphones, las smartTV\ y otros tantos dispositivos: la autenticaci{\'o}n, la distribuci{\'o}n y al fin y al cabo, la comunicaci{\'o}n entre extremos puede verse seriamente comprometida si dicha plataforma es atacada. La inclusi{\'o}n de nuevas medidas de seguridad en este tipo de ecosistemas requiere de un cambios sustancial de la arquitectura subyacente en muchos casos, por lo que su avance es lento.\ 
En este trabajo se trata de forma concreta el desarrollo de una alternativa OpenSource\ a uno de estos servicios, la telefon{\'\i}a IP (VoIP), que esta expandi{\'e}ndose cada d{\'\i}a m{\'a}s, empezando por redes locales y privadas y llegando a grandes centralitas de conmutaci{\'o}n de tele operadoras, consiguiendo as{\'\i} una transmisi{\'o}n de voz segura extremo a extremo transparente para los servidores VoIP, que no requiera modificar la infraestructura subyacente.

}, author = {Ra{\'u}l Oca{\~n}a and Isaac Agudo} } @article {alcaraz2019a, title = {Covert Channels-based Stealth Attacks in Industry 4.0}, journal = {IEEE Systems Journal.}, volume = {13}, year = {2019}, month = {12/2019}, pages = {3980-3988}, publisher = {IEEE}, abstract = {

Industry 4.0 advent opens several cyber-threats scenarios originally designed for classic information technology, drawing the attention to the serious risks for the modern industrial control networks.\ To cope with this problem, in this paper we address the security issues related to covert channels applied to industrial networks, identifying the new vulnerability points when information technologies converge with operational technologies such as edge computing infrastructures.\ Specifically, we define two signaling strategies where we exploit the Modbus/TCP protocol as target to set up a covert channel. Once the threat channel is established, passive and active offensive attacks (i.e. data exfiltration and command an control, respectively) are further exploited by implementing and testing them on a real Industrial Internet of Things testbed.\ The experimental results highlight the potential damage of such specific threats, and the easy extrapolation of the attacks to other types of channels in order to show the new risks for Industry 4.0. Related to this, we discuss some countermeasures to offer an overview of possible mitigation and defense measures.

}, issn = {1932-8184}, doi = {https://doi.org/10.1109/JSYST.2019.2912308}, url = {https://ieeexplore.ieee.org/document/8715420?source=authoralert}, author = {Cristina Alcaraz and Giuseppe Bernieri and Federica Pascucci and Javier Lopez and Roberto Setola} } @article {rub2019cose, title = {Current Cyber-Defense Trends in Industrial Control Systems}, journal = {Computers \& Security Journal}, volume = {87}, year = {2019}, month = {11/2019}, publisher = {Elsevier}, type = {SECRYPT 2017 Special Issue}, abstract = {

Advanced Persistent Threats (APTs) have become a serious hazard for any critical infrastructure, as a single solution to protect all industrial assets from these complex attacks does not exist. It is then essential to understand what are the defense mechanisms that can be used as a first line of defense. For this purpose, this article will firstly study the spectrum of attack vectors that APTs can use against existing and novel elements of an industrial ecosystem. Afterwards, this article will provide an analysis of the evolution and applicability of Intrusion Detection Systems (IDS) that have been proposed in both the industry and academia.

}, keywords = {APT, Industrial Control, Industry 4.0, Intrusion Detection, SCADA}, issn = {0167-4048}, doi = {https://doi.org/10.1016/j.cose.2019.06.015}, author = {Juan E. Rubio and Cristina Alcaraz and Rodrigo Roman and Javier Lopez} } @inproceedings {1985, title = {Desarrollo de un sem{\'a}foro inteligente basado en comunicaciones seguras}, booktitle = {XIV Jornadas de Ingenier{\'\i}a Telem{\'a}tica (JITEL 2019)}, year = {2019}, month = {10/2019}, abstract = {

En los nuevos paradigmas de movilidad surgidos durante los {\'u}ltimos a{\~n}os y en aquellos a{\'u}n por llegar ha quedado patente la necesidad de modernizar la infraestructura viaria y los elementos de se{\~n}alizaci{\'o}n y gesti{\'o}n del tr{\'a}fico. En el presente trabajo se presenta una propuesta para esta nueva generaci{\'o}n de dispositivos de gesti{\'o}n del tr{\'a}fico: un prototipo de sem{\'a}foro inteligente conectado que implementa diversas medidas de seguridad. Adem{\'a}s de las tradicionales se{\~n}ales luminosas, los usuarios de la v{\'\i}a pueden conocer a trav{\'e}s de sus dispositivos el estado del sem{\'a}foro, adem{\'a}s de otra informaci{\'o}n complementaria a trav{\'e}s de la difusi{\'o}n de mensajes BLE firmados con criptograf{\'\i}a de curva el{\'\i}ptica. A su vez, el sem{\'a}foro puede ser gestionado remotamente a trav{\'e}s de la tecnolog{\'\i}a LTE Cat M1 protegida por TLS. Esto abre la puerta, entre otros, a facilitar el tr{\'a}nsito de los veh{\'\i}culos de emergencia cuando estos se acercan a un cruce o modificar el tiempo de los estados del ciclo en funci{\'o}n de las necesidades del tr{\'a}fico.

}, author = {Isaac Agudo and Manuel Montenegro-G{\'o}mez} } @article {sarita2018, title = {Detection of Node Capture Attack in Wireless Sensor Networks}, journal = {IEEE Systems Journal}, volume = {13}, year = {2019}, month = {03/2019}, pages = {238 - 247}, publisher = {IEEE}, issn = {1932-8184}, author = {Sarita Agrawal and Manik Lal Das and Javier Lopez} } @inproceedings {RubioESORICS2019, title = {Enhancing Security and Dependability of Industrial Networks with Opinion Dynamics}, booktitle = {European Symposium on Research in Computer Security (ESORICS2019)}, volume = {11736}, year = {2019}, month = {09/2019}, pages = {263-280}, doi = {https://doi.org/10.1007/978-3-030-29962-0_13}, author = {Juan E. Rubio and Mark Manulis and Cristina Alcaraz and Javier Lopez} } @article {nunez19, title = {Escrowed decryption protocols for lawful interception of encrypted data}, journal = {IET Information Security}, volume = {13}, year = {2019}, month = {09/2019}, pages = {498 -- 507}, publisher = {IET}, abstract = {

Escrowed decryption schemes (EDSs) are public-key encryption schemes with an escrowed decryption functionality that allows authorities to decrypt encrypted messages under investigation, following a protocol that involves a set of trusted entities called {\textquoteleft}custodians{\textquoteright}; only if custodians collaborate, the requesting authority is capable of decrypting encrypted data. This type of cryptosystem represents an interesting trade-off to privacy versus surveillance dichotomy. In this study, the authors propose two EDSs where they use proxy re-encryption to build the escrowed decryption capability, so that custodians re-encrypt ciphertexts, in a distributed way, upon request from an escrow authority, and the re-encrypted ciphertexts can be opened only by the escrow authority. Their first scheme, called EDS, follows an all-or-nothing approach, which means that escrow decryption only works when all custodians collaborate. Their second scheme, called threshold EDS, supports a threshold number of custodians for the escrow decryption operation. They propose definitions of semantic security with respect to the authorities, custodians and external entities, and prove the security of their schemes, under standard pairing-based hardness assumptions. Finally, they present a theoretical and experimental analysis of the performance of both schemes, which show that they are applicable to real-world scenarios.

}, issn = {1751-8709}, author = {David Nu{\~n}ez and Isaac Agudo and Javier Lopez} } @inproceedings {1835, title = {Personalized Computer Security Tasks with Automatic Evaluation and Feedback}, booktitle = {International Conference on Information Systems Education and Research (AIS SIGED 2019)}, year = {2019}, month = {12/2019}, keywords = {autonomy, evaluation, feedback, learn by doing, Moodle, self-learning}, isbn = {978-1-7343123-0-0}, author = {Isaac Agudo and Ruben Rios and Ana Nieto} } @inproceedings {morales2019, title = {Prueba de concepto de Autoridad de Certificaci{\'o}n usando Computaci{\'o}n Segura Multiparte}, booktitle = {XIV Jornadas de Ingenier{\'\i}a Telem{\'a}tica}, year = {2019}, month = {10/2019}, pages = {50-53}, address = {Zaragoza}, abstract = {Este trabajo pretende analizar el paradigma de la Computaci{\'o}n Segura Multiparte y sus posibles aplicaciones en el campo de la criptograf{\'\i}a. Se plantea como modelo alternativo, mas escalable y seguro al uso de m{\'o}dulos hardware de seguridad para aplicaciones que requieran de Terceras Partes Confiables. Concretamente, se ha integrado un protocolo de criptograf{\'\i}a RSA multiparte con la librer{\'\i}a certbuilder, para la creaci{\'o}n de certificados X.509. De esta forma se asegura que la creaci{\'o}n de los certificados ra{\'\i}z de la Infraestructura de Clave Publica se realiza de forma que la generaci{\'o}n de claves y firma de este se ejecute {\'\i}ntegramente sobre el sistema multiparte, con un modelo de tres partes que trabaja con circuitos aritm{\'e}ticos, sin que ninguna de ellas, de forma aislada, tenga posibilidad de comprometer la clave privada correspondiente. Para comprobar la viabilidad del sistema se han realizado pruebas de generaci{\'o}n de certificados con diferentes longitudes de clave, siendo el proceso determinante la creaci{\'o}n de las claves. Los elevados tiempos hacen que una aplicaci{\'o}n como esta no sea asumible en otros escenarios, pero creemos que para el caso de la creaci{\'o}n de los certificados ra{\'\i}z de una infraestructura de clave p{\'u}blica las garant{\'\i}as avanzadas de seguridad compensan el tiempo extra. }, keywords = {privacy, Secure Multiparty computation}, isbn = {978-84-09-21112-8}, doi = {10.26754/uz.978-84-09-21112-8}, author = {Daniel Morales and Isaac Agudo} } @inproceedings {1815, title = {SealedGRID: A Secure Interconnection of Technologies for Smart Grid Applications}, booktitle = {14th International Conference on Critical Information Infrastructures Security (CRITIS 2019)}, volume = {11777}, year = {2019}, month = {12/2019}, pages = {169-175}, publisher = {Springer, Cham}, organization = {Springer, Cham}, abstract = {

In recent years, the Smart Grid has increasingly integrated cutting-edge technologies that generate several benefits for all the stakeholders involved, such as a more accurate billing system and enhanced Demand Response procedures. However, this modernization also brings with it diverse cyber security and privacy issues, which sets the necessity for developing a security platform specifically tailored to this scenario. In this paper, we present SealedGRID, which proposes a flexible architecture that provides security services at all levels by implementing Trusted Execution Environments on their devices, together with advanced authentication and authorization mechanisms, as well as privacy preserving techniques. These technologies are presented in depth and a final security analysis is conducted, which highlights the contributions of this project.

}, isbn = {978-3-030-37669-7}, doi = {https://doi.org/10.1007/978-3-030-37670-3_14}, author = {Aristeidis Farao and Juan E. Rubio and Cristina Alcaraz and Christoforos Ntantogian and Christos Xenakis and Javier Lopez} } @incollection {alcaraz2019, title = {Secure Interconnection of IT-OT Networks in Industry 4.0}, booktitle = {Critical Infrastructure Security and Resilience: Theories, Methods, Tools and Technologies}, number = {Advanced Sciences and Technologies for Security Applications book series (ASTSA)}, year = {2019}, month = {01/2019}, pages = {201-217}, publisher = {Springer International Publishing}, organization = {Springer International Publishing}, abstract = {

Increasingly, the society is witnessing how today{\textquoteright}s industry is adapting\ the new technologies and communication protocols to offer more optimal and reliable\ services to end-users, with support for inter-domain communication belonging\ to diverse critical infrastructures. As a consequence of this technological revolution,\ interconnection mechanisms are required to offer transparency in the connections\ and protection in the different application domains, without this implying a significant\ degradation of the control requirements. Therefore, this book chapter presents\ a reference architecture for the new Industry 4.0 where the interconnection core is\ mainly concentrated in the Policy Decision Points (PDP), which can be deployed\ in high volume data processing and storage technologies such as cloud and fog\ servers. Each PDP authorizes actions in the field/plant according to a set of factors\ (entities, context and risks) computed through the existing access control measures,\ such as RBAC+ABAC+Risk-BAC (Role/Attribute/Risk-Based Access Control, respectively),\ to establish coordinated and constrained accesses in extreme situations.\ Part of these actions also includes proactive risk assessment measures to respond to\ anomalies or intrusive threats in time.

}, isbn = {978-3-030-00024-0}, doi = {https//doi.org/10.1007/978-3-030-00024-0_11}, url = {https://doi.org/10.1007/978-3-030-00024-0_11}, author = {Cristina Alcaraz} } @book {1776, title = {Security and Privacy Trends in the Industrial Internet of Things}, series = {Advanced Sciences and Technologies for Security Applications}, year = {2019}, publisher = {Springer}, organization = {Springer}, keywords = {Critical Infrastructure Protection, Industrial Internet of Things, SCADA Systems}, isbn = {978-3-030-12330-7}, url = {https://www.springer.com/gp/book/9783030123291}, author = {Cristina Alcaraz} } @article {RubioSIJCS19, title = {Tracking APTs in Industrial Ecosystems: A Proof of Concept}, journal = {Journal of Computer Security}, volume = {27}, year = {2019}, month = {09/2019}, pages = {521-546}, publisher = {Elsevier}, type = {ESORICS 2018 Special Issue }, issn = {0167-4048}, author = {Juan E. Rubio and Rodrigo Roman and Cristina Alcaraz and Yan Zhang} } @inproceedings {1692, title = {Addressing Security in OCPP: Protection Against Man-in-the-Middle Attacks}, booktitle = {9th IFIP International Conference on New Technologies, Mobility \& Security}, year = {2018}, author = {Juan E. Rubio and Cristina Alcaraz and Javier Lopez} } @inproceedings {1709, title = {Analyzing cross-platform attacks: towards a three-actor approach}, booktitle = {The 16th IEEE International Conference on Dependable, Autonomic and Secure Computing (DASC 2018)}, year = {2018}, month = {08/2018}, pages = {536-543}, abstract = {


In the current telecommunications landscape, different devices, systems and platforms are constantly communicating with each other. This heterogeneous environment creates the perfect situation for attacks to pass from one platform to another. This is a particularly worrying scenario, because of the new technologies being used (such as network slicing in 5G), the increasing importance of connected devices in our lives (IoT), and the unpredictable consequences that an attack of this type could have. The current approaches in attack analysis do not take into account these sitations, and the attacker/victim paradigm usually followed may fall short when dealing with these attacks. Thus, in this paper, an architecture for the analysis of cross-platform attacks will be presented, aiming to help understand better this kind of threats and offering solutions to mitigate and track them.

}, isbn = {978-1-5386-7518-2}, doi = {10.1109/DASC/PiCom/DataCom/CyberSciTec.2018.00102}, author = {Antonio Acien and Ana Nieto and Javier Lopez} } @inproceedings {CRAT2018, title = {Capture the RAT: Proximity-based Attacks in 5G using the Routine Activity Theory}, booktitle = {The 16th IEEE International Conference on Dependable, Autonomic and Secure Computing (DASC 2018)}, year = {2018}, month = {08/2018}, pages = {520-527}, publisher = {IEEE}, organization = {IEEE}, address = {Athens, Greece}, abstract = {

The fifth generation of cellular networks (5G) will enable different use cases where security will be more critical than ever before (e.g. autonomous vehicles and critical IoT devices). Unfortunately, the new networks are being built on the certainty that security problems can not be solved in the short term. Far from reinventing the wheel, one of our goals is to allow security software developers to implement and test their reactive solutions for the capillary network of 5G devices. Therefore, in this paper a solution for analysing proximity-based attacks in 5G environments is modelled and tested using OMNET++. The solution, named CRAT, is able to decouple the security analysis from the hardware of the device with the aim to extend the analysis of proximity-based attacks to different use-cases in 5G. We follow a high-level approach, in which the devices can take the role of victim, offender and guardian following the principles of the routine activity theory.\ 

}, isbn = {978-1-5386-7518-2}, doi = {10.1109/DASC/PiCom/DataCom/CyberSciTec.2018.00100}, url = {https://ieeexplore.ieee.org/document/8511943}, author = {Ana Nieto and Antonio Acien and Javier Lopez} } @article {Alcaraz2018a, title = {Cloud-Assisted Dynamic Resilience for Cyber-Physical Control Systems}, journal = {IEEE Wireless Communications}, volume = {25}, number = {1}, year = {2018}, month = {02/2018}, pages = {76-82}, publisher = {IEEE}, keywords = {Cloud Computing, Computer architecture, Controllability, Edge computing, Redundancy, resilience}, issn = {1536-1284}, doi = {10.1109/MWC.2018.1700231}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=8304395\&isnumber=8304374}, author = {Cristina Alcaraz} } @inproceedings {1701, title = {A comprehensive methodology for deploying IoT honeypots}, booktitle = {15th International Conference on Trust, Privacy and Security in Digital Business (TrustBus 2018)}, volume = {LNCS 11033}, year = {2018}, month = {09/2018}, pages = {229{\textendash}243}, publisher = {Springer Nature Switzerland AG}, organization = {Springer Nature Switzerland AG}, address = {Regensburg (Germany)}, abstract = {

Recent news have raised concern regarding the security on the IoT field. Vulnerabilities in devices are arising and honeypots are an excellent way to cope with this problem. In this work, current solutions for honeypots in the IoT context, and other solutions adaptable to it are analyzed in order to set the basis for a methodology that allows deployment of IoT honeypot.

}, keywords = {Honeypot, IoT, methodology, security}, doi = {https://doi.org/10.1007/978-3-319-98385-1_16}, author = {Antonio Acien and Ana Nieto and Gerardo Fernandez and Javier Lopez} } @article {NAFMONET2018, title = {Crowdsourcing analysis in 5G IoT: Cybersecurity Threats and Mitigation}, journal = {Mobile Networks and Applications (MONET)}, year = {2018}, month = {10/2018}, pages = {881-889}, publisher = {Springer US}, abstract = {
Crowdsourcing can be a powerful weapon against cyberattacks in 5G networks. In this paper we analyse this idea in detail, starting from the use cases in crowdsourcing focused on security, and highlighting those areas of a 5G ecosystem where crowdsourcing could be used to mitigate local and remote attacks, as well as to discourage criminal activities and cybercriminal behaviour. We pay particular attention to the capillary network, where an infinite number of IoT objects coexist. The analysis is made considering the different participants in a 5G IoT ecosystem.
}, keywords = {5G security, Cybersecurity, digital witness, Proactive security}, issn = {1383-469X}, doi = {https://doi.org/10.1007/s11036-018-1146-4}, author = {Ana Nieto and Antonio Acien and Gerardo Fernandez} } @article {cazorla2016cyber, title = {Cyber Stealth Attacks in Critical Information Infrastructures}, journal = {IEEE Systems Journal}, volume = {12}, year = {2018}, month = {06/2018}, pages = {1778-1792}, publisher = {IEEE}, abstract = {

Current Critical Infrastructures (CIs) are complex interconnected industrial systems that, in recent years, have incorporated information and communications technologies such as connection to the Internet and commercial off-the-shelf components. This makes them easier to operate and maintain, but exposes them to the threats and attacks that inundate conventional networks and systems. This paper contains a comprehensive study on the main stealth attacks that threaten CIs, with a special focus on Critical Information Infrastructures (CIIs). This type of attack is characterized by an adversary who is able to finely tune his actions to avoid detection while pursuing his objectives. To provide a complete analysis of the scope and potential dangers of stealth attacks we determine and analyze their stages and range, and we design a taxonomy to illustrate the threats to CIs, offering an overview of the applicable countermeasures against these attacks. From our analysis we understand that these types of attacks, due to the interdependent nature of CIs, pose a grave danger to critical systems where the threats can easily cascade down to the interconnected systems.\ 

}, keywords = {Control systems, Countermeasures, Critical Infrastructures, Detection and Protection, Stealth Attacks}, issn = {1932-8184}, doi = {10.1109/JSYST.2015.2487684}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=7445136\&isnumber=8350419}, author = {Lorena Cazorla and Cristina Alcaraz and Javier Lopez} } @article {alcarazlopez-IEEESystems-2017, title = {A Cyber-Physical Systems-Based Checkpoint Model for Structural Controllability}, journal = {IEEE Systems Journal}, volume = {12}, year = {2018}, month = {12/2018}, pages = {3543-3554}, publisher = {IEEE}, abstract = {

The protection of critical user-centric applications,\ such as Smart Grids and their monitoring systems, has become\ one of the most cutting-edge research areas in recent years.\ The dynamic complexity of their cyber-physical systems (CPSs)\ and their strong inter-dependencies with power systems, are\ bringing about a significant increase in security problems that\ may be exploited by attackers. These security holes may, for\ example, trigger the disintegration of the structural controllability\ properties due to the problem of non-locality, affecting, sooner\ or later, the provision of the essential services to end-users.\ One way to address these situations could be through automatic\ checkpoints in charge of inspecting the healthy status of the\ control network and its critical nature. This inspection can be\ subject to special mechanisms\ composed of trustworthy cyberphysical\ elements\ capable of detecting structural changes in the\ control and activating restoration procedures\ with support for\ warning. This is precisely the aim of this paper, which presents\ a CPSs-based checkpoint model with the capacity to manage\ heterogeneous replications that help ensure data redundancy,\ thereby guaranteeing the validity of the checkpoints. As a support\ to this study,\ a theoretical and practical analysis is addressed to\ show the functionality of the approach in real contexts.

}, keywords = {Critical Control Systems, cyber-physical systems, Smart grids, structural controllability}, issn = {1932-8184}, doi = {https://doi.org/10.1109/JSYST.2017.2740719}, url = {http://ieeexplore.ieee.org/document/8057984/}, author = {Cristina Alcaraz and Javier Lopez} } @inproceedings {1706, title = {Definici{\'o}n de procedimientos para fabricar honeypots IoT basados en criterios de b{\'u}squeda}, booktitle = {XV Reuni{\'o}n Espa{\~n}ola sobre Criptolog{\'\i}a y Seguridad de la Informaci{\'o}n}, year = {2018}, month = {10/2018}, address = {Granada (Espa{\~n}a)}, abstract = {

Con la revoluci{\'o}n tecnol{\'o}gica que ha supuesto la Internet de las Cosas (Internet of Things, IoT) se han presentado escenarios donde la preocupaci{\'o}n por la seguridad en dicho entorno es cada vez m{\'a}s relevante. Est{\'a}n comenzando a surgir vulnerabilidades en varios dispositivos, y los sistemas trampa son una excelente manera de lidiar con este problema. En este trabajo se analizan soluciones para honeypots en el entorno IoT (y en otros que se puedan adaptar) para sentar las bases de una metodolog{\'\i}a que permita el despliegue de honeypots IoT.

}, isbn = {978-84-09-02463-6}, author = {Antonio Acien and Ana Nieto and Gerardo Fernandez and Javier Lopez} } @proceedings {alcaraz2018a, title = {International Workshop on Security and Trust Management 2018}, journal = {International Workshop on Security and Trust Management}, volume = {11091}, year = {2018}, month = {09/2018}, publisher = {Springer International Publishing}, edition = {LNCS}, address = {Springer Nature Switzerland }, isbn = {978-3-030-01141-3}, issn = {1611-3349}, doi = {https://doi.org/10.1007/978-3-030-01141-3}, url = {https://link.springer.com/book/10.1007\%2F978-3-030-01141-3$\#$about}, author = {Sokratis K. Katsikas and Cristina Alcaraz} } @inproceedings {1699, title = {Modelo para la clasificaci{\'o}n y an{\'a}lisis de ataques Cross-Platform}, booktitle = {IV Jornadas Nacionales de Investigaci{\'o}n en Ciberseguridad (JNIC 2018)}, year = {2018}, month = {06/2018}, publisher = {Servicio Editorial de Mondragon Unibertsitatea}, organization = {Servicio Editorial de Mondragon Unibertsitatea}, address = {Donostia-San Sebasti{\'a}n (Espa{\~n}a)}, abstract = {

Los ataques cross-platform suponen un serio desaf{\'\i}o para los mecanismos de seguridad cuando los portadores de un ataque dirigido no son conscientes de su participacion en el mismo. Es por ello que, con dispositivos y tecnolog{\'\i}as cada vez mas entrelazadas, en constante comunicaci{\'o}n, numerosos ataques pasan desapercibidos hasta que alcanzan su objetivo final. Estos nuevos escenarios hacen posible una v{\'\i}a de transmision a tener en cuenta, y que se debe abordar cuanto antes, ya que sus consecuencias, especialmente en el panorama de telecomunicaciones actual, podr{\'\i}an ser desoladoras. La rapida transmisi{\'o}n de estos ataques, y la dificultad que supone su prevencion, detecci{\'o}n y mitigaci{\'o}n antes de que se hagan efectivos, hacen que el problema sea particularmente preocupante. En este art{\'\i}culo se presentar{\'a} una arquitectura para el analisis de los ataques cross-platform silenciosos, cuyo objetivo es ayudar a comprender mejor este tipo de amenazas y ofrecer soluciones que permitan mitigarlas y rastrearlas.

}, keywords = {architecture, attack, Cross-platform, security}, isbn = {978-84-09-02697-5}, url = {http://2018.jnic.es/assets/Actas_JNIC2018.pdf}, author = {Antonio Acien and Ana Nieto and Javier Lopez} } @article {transactionInformaticsSG2018, title = {A Resilient Architecture for the Smart Grid}, journal = {IEEE Transactions on Industrial Informatics}, volume = {14}, year = {2018}, month = {08/2019}, pages = {3745-3753}, publisher = {IEEE}, type = {Journal}, abstract = {

The Smart Grid offers many benefits due to the bidirectional communication between the users and the utility company, which makes it possible to perform a fine-grain consumption metering. This can be used for Demand Response purposes with the generation and delivery of electricity in real time. It is essential to rapidly anticipate high peaks of demand or potential attacks, so as to avoid power outages and denial of service, while effectively supplying consumption areas. In this paper, we propose a novel architecture where cloud computing resources are leveraged (and tested in practice) to enable, on the one hand, the consumption prediction through time series forecasting, as well as load balancing to uniformly distribute the demand over a set of available generators. On the other and,\ it also allows the detection of connectivity losses and intrusions within the control network by using controllability concepts.

}, issn = {1551-3203}, doi = {10.1109/TII.2018.2826226}, author = {Javier Lopez and Juan E. Rubio and Cristina Alcaraz} } @article {IonnaisPanosMihalisAlcarazLopez2018, title = {Survey of IoT-enabled Cyberattacks: Assessing Attack Paths to Critical Infrastructures and Services}, journal = { IEEE Communications Surveys and Tutorials}, volume = {20}, year = {2018}, month = {07/2018}, pages = {3453-3495}, publisher = {IEEE}, abstract = {

As the deployment of Internet of Things (IoT)\ is experiencing an exponential growth, it is no surprise that\ many recent cyber attacks are IoT-enabled: The attacker initially\ exploits some vulnerable IoT technology as a first step towards\ compromising a critical system that is connected, in some way,\ with the IoT. For some sectors, like industry, smart grids,\ transportation and medical services, the significance of such\ attacks is obvious, since IoT technologies are part of critical backend\ systems. However, in sectors where IoT is usually at the enduser\ side, like smart homes, such attacks can be underestimated,\ since not all possible attack paths are examined. In this paper\ we survey IoT-enabled cyber attacks, found in all application\ domains since 2010. For each sector, we emphasize on the latest,\ verified IoT-enabled attacks, based on known real-world incidents\ and published proof-of-concept attacks. We methodologically\ analyze representative attacks that demonstrate direct, indirect\ and subliminal attack paths against critical targets. Our goal is\ threefold: (i) To assess IoT-enabled cyber attacks in a risk-like\ approach, in order to demonstrate their current threat landscape;\ (ii) To identify hidden and subliminal IoT-enabled attack paths\ against critical infrastructures and services, and (iii) To examine\ mitigation strategies for all application domains.

}, keywords = {Critical Infrastructures, Cyber Attacks, Intelligent Transportation Systems, Internet of Things, SCADA, Smart grids, Smart Home, Smart Medical Systems}, issn = {1553-877X}, doi = {https://doi.org/10.1109/COMST.2018.2855563}, url = {https://ieeexplore.ieee.org/document/8410404}, author = {Ioannis Stellios and Panayiotis Kotzanikolaou and Mihalis Psarakis and Cristina Alcaraz and Javier Lopez} } @inproceedings {RubioRomanAlcarazZhang2018, title = {Tracking Advanced Persistent Threats in Critical Infrastructures through Opinion Dynamics}, booktitle = {European Symposium on Research in Computer Security (ESORICS 2018)}, volume = {11098}, year = {2018}, month = {08/2018}, pages = {555-574}, publisher = {Springer}, organization = {Springer}, address = {Barcelona, Spain}, abstract = {

Advanced persistent threats pose a serious issue for modern industrial environments, due to their targeted and complex attack vectors that are difficult to detect. This is especially severe in critical infrastructures that are accelerating the integration of IT technologies. It is then essential to further develop effective monitoring and response systems that ensure the continuity of business to face the arising set of cyber-security threats. In this paper, we study the practical applicability of a novel technique based on opinion dynamics, that permits to trace the attack throughout all its stages along the network by correlating different anomalies measured over time, thereby taking the persistence of threats and the criticality of resources into consideration. The resulting information is of essential importance to monitor the overall health of the control system and correspondingly deploy accurate response procedures.

}, keywords = {Advanced Persistent Threat, Detection, Opinion Dynamics, Traceability}, doi = {10.1007/978-3-319-99073-6_27}, url = {https://link.springer.com/chapter/10.1007/978-3-319-99073-6_27}, author = {Juan E. Rubio and Rodrigo Roman and Cristina Alcaraz and Yan Zhang} } @inproceedings {1662, title = {Analysis of Intrusion Detection Systems in Industrial Ecosystems}, booktitle = {14th International Conference on Security and Cryptography (SECRYPT 2017)}, volume = {6}, year = {2017}, pages = {116-128}, publisher = {SciTePress}, organization = {SciTePress}, isbn = {978-989-758-259-2}, doi = {10.5220/0006426301160128}, author = {Juan E. Rubio and Cristina Alcaraz and Rodrigo Roman and Javier Lopez} } @incollection {1590, title = {Cyber-Physical Systems for Wide-Area Situational Awareness}, booktitle = {Cyber-Physical Systems: Foundations, Principles and Applications}, number = {Intelligent Data-Centric Systems}, year = {2017}, month = {2017}, pages = {305 - 317}, publisher = {Academic Press}, organization = {Academic Press}, chapter = {20}, address = {Boston}, abstract = {

Abstract Cyber-physical systems (CPSs), integrated in critical infrastructures, could provide the minimal services that traditional situational awareness (SA) systems demand. However, their application in SA\ solutions for the protection of large control distributions against unforeseen faults may be insufficient. Dynamic protection measures have to be provided not only to locally detect unplanned deviations but also to prevent, respond, and restore from these deviations. The provision of these services as an integral part of the SA\ brings about a new research field known as wide-area situational awareness (WASA), highly dependent on CPSs\ for control from anywhere across multiple interconnections, and at any time. Thus, we review the state-of-the art of this new paradigm, exploring the different preventive and corrective measures considering the heterogeneity of CPSs, resulting in a guideline for the construction of automated WASA\ systems.

}, keywords = {Control systems, Critical Infrastructure Protection, cyber-physical systems, Detection, Response, restoration, Wide-Area Situational Awareness}, isbn = {978-0-12-803801-7}, doi = {http://dx.doi.org/10.1016/B978-0-12-803801-7.00020-1}, author = {Cristina Alcaraz and Lorena Cazorla and Javier Lopez} } @inproceedings {1653, title = {Estado y Evoluci{\'o}n de la Detecci{\'o}n de Intrusiones en los Sistemas Industriales}, booktitle = {III Jornadas Nacionales de Investigaci{\'o}n en Ciberseguridad (JNIC 2017)}, year = {2017}, abstract = {

Debido a la necesidad de proteger los sistemas\ industriales ante amenazas, se hace necesario comprender cual\ es el verdadero alcance de los mecanismos capaces de detectar\ potenciales anomal{\'\i}as e intrusiones. Es por tanto el objetivo de\ este art{\'\i}culo analizar el estado y la evoluci{\'o}n, tanto acad{\'e}mica\ como industrial, de los mecanismos de detecci{\'o}n de intrusiones\ en este campo, as{\'\i}\ como estudiar su aplicabilidad actual y futura.

}, author = {Cristina Alcaraz and Jes{\'u}s Rodriguez and Roman, Rodrigo and Juan E. Rubio} } @inproceedings {nunez2017fallout, title = {The fallout of key compromise in a proxy-mediated key agreement protocol}, booktitle = {31st Annual IFIP WG 11.3 Conference on Data and Applications Security and Privacy (DBSec{\textquoteright}17)}, volume = {LNCS 10359}, year = {2017}, month = {07/2017}, pages = {453-472}, publisher = {Springer}, organization = {Springer}, address = {Philadelphia, USA}, abstract = {

In this paper, we analyze how key compromise affects the protocol by Nguyen et al. presented at ESORICS 2016, an authenticated key agreement protocol mediated by a proxy entity, restricted to only symmetric encryption primitives and intended for IoT environments. This protocol uses long-term encryption tokens as intermediate values during encryption and decryption procedures, which implies that these can be used to encrypt and decrypt messages without knowing the cor- responding secret keys. In our work, we show how key compromise (or even compromise of encryption tokens) allows to break forward secu- rity and leads to key compromise impersonation attacks. Moreover, we demonstrate that these problems cannot be solved even if the affected user revokes his compromised secret key and updates it to a new one. The conclusion is that this protocol cannot be used in IoT environments, where key compromise is a realistic risk.\ 

}, isbn = {978-3-319-61176-1}, doi = {10.1007/978-3-319-61176-1_25}, author = {David Nu{\~n}ez and Isaac Agudo and Javier Lopez} } @article {AlcarazLopezWolthusen2017, title = {OCPP Protocol: Security Threats and Challenges}, journal = {IEEE Transactions on Smart Grid}, volume = {8}, year = {2017}, month = {02/2017}, pages = {2452 - 2459}, publisher = {IEEE}, abstract = {

One benefit postulated for the adoption of Electric Vehicles (EVs) is their\ ability to act as stabilizing entities in smart grids through bi-directional charging,\ allowing local or global smoothing of peaks and imbalances. This benefit,\ however, hinges indirectly on the reliability and security of the power flows\ thus achieved. Therefore this paper studies key security properties of the alreadydeployed\ Open Charge Point Protocol (OCPP) specifying communication between\ charging points and energy management systems. It is argued that possible subversion\ or malicious endpoints in the protocol can also lead to destabilization of\ power networks. Whilst reviewing these aspects, we focus, from a theoretical and\ practical standpoint, on attacks that interfere with resource reservation originating\ with the EV, which may also be initiated by a man in the middle, energy theft or\ fraud. Such attacks may even be replicated widely, resulting in over- or undershooting\ of power network provisioning, or the (total/partial) disintegration of the\ integrity and stability of power networks.

}, keywords = {Charging Infrastructure, Cyber Security, Cyber- Physical Systems, OCPP, Smart Grid}, issn = {1949-3053 }, doi = {https://doi.org/10.1109/TSG.2017.2669647}, author = {Cristina Alcaraz and Javier Lopez and Stephen Wolthunsen} } @inproceedings {RubioAlcarazLopez2017ESORICS, title = {Preventing Advanced Persistent Threats in Complex Control Networks}, booktitle = {European Symposium on Research in Computer Security}, volume = {10493}, year = {2017}, month = {09/2017}, pages = {402-418}, publisher = {22nd European Symposium on Research in Computer Security (ESORICS 2017)}, organization = {22nd European Symposium on Research in Computer Security (ESORICS 2017)}, author = {Juan E. Rubio and Cristina Alcaraz and Javier Lopez} } @article {lopez2017ecn, title = {Protecting Industry 4.0 against Advanced Persistent Threats}, journal = {European CIIP Newsletter}, volume = {11}, number = {1}, year = {2017}, month = {03/2017}, pages = {27-29}, publisher = {European CIIP Newsletter}, issn = {NONE}, author = {Javier Lopez and Cristina Alcaraz and Jes{\'u}s Rodriguez and Rodrigo Roman and Juan E. Rubio} } @article {nunez2017proxy, title = {Proxy Re-Encryption: Analysis of Constructions and its Application to Secure Access Delegation}, journal = {Journal of Network and Computer Applications}, volume = {87}, year = {2017}, month = {06/2017}, pages = {193-209}, publisher = {Elsevier}, abstract = {

This paper analyzes the secure access delegation problem, which occurs naturally in the cloud, and postulate that Proxy Re-Encryption is a feasible cryptographic solution, both from the functional and efficiency perspectives. Proxy re-encryption is a special type of public-key encryption that permits a proxy to transform ciphertexts from one public key to another, without the proxy being able to learn any information about the original message. Thus, it serves as a means for delegating decryption rights, opening up many possible applications that require of delegated access to encrypted data. In particular, sharing information in the cloud is a prime example. In this paper, we review the main proxy re-encryption schemes so far, and provide a detailed analysis of their characteristics. Additionally, we also study the efficiency of selected schemes, both theoretically and empirically, based on our own implementation. Finally, we discuss some applications of proxy re-encryption, with a focus on secure access delegation in the cloud.\ 

}, issn = {1084-8045}, doi = {10.1016/j.jnca.2017.03.005}, author = {David Nu{\~n}ez and Isaac Agudo and Javier Lopez} } @article {rubiorecommender17, title = {Recommender System for Privacy-Preserving Solutions in Smart Metering}, journal = {Pervasive and Mobile Computing}, volume = {41}, year = {2017}, month = {10/2017}, pages = {205-218}, publisher = {Pervasive and Mobile Computing}, abstract = {

Nowadays, Smart Grid is envisaged to provide several benefits to both customers and grid operators. However, Smart Meters introduce many privacy issues if consumption data is analysed. In this paper we analyse the main techniques that address privacy when collecting electricity readings. In addition to privacy, it is equally important to preserve efficiency to carry on with monitoring operations, so further control requirements and communication protocols are also studied. Our aim is to provide guidance to installers who intend to integrate such mechanisms on the grid, presenting an expert system to recommend an appropriate deployment strategy.

}, issn = {1574-1192}, author = {Juan E. Rubio and Cristina Alcaraz and Javier Lopez} } @article {Alcaraz:2017:IJCIS, title = {Resilient Industrial Control Systems based on Multiple Redundancy}, journal = {International Journal of Critical Infrastructures (IJCIS)}, volume = {13}, number = {2/3}, year = {2017}, month = {11/2017}, pages = {278 - 295}, publisher = {Inderscience Publisher}, address = {London, UK}, abstract = {

The incessant search for cost-effective recovery solutions for structural\ controllability has led to one of the most challenging research areas within the\ field of critical infrastructure protection. The resilience of large heterogeneous\ distributions, like industrial control scenarios, is proving to be a complicated\ mission due to the inherent non-locality problems of structural controllability and\ its susceptibility to advanced threats. To address these issues, this paper proposes a\ new repair approach based on multiple redundant pathways and the lessons learnt\ from the work presented in [1]. From [1], we have adapted the local measures, to\ combine them with each of the five strategies of remote reconnection described in\ this paper. To validate the sustainability of the combined approaches, two practical\ case studies are presented here, showing that a local dependence on a brother\ driver node together with remote dependence is enough to reach optimal states\ in linear times.

}, issn = {1741-8038}, doi = {http://dx.doi.org/10.1504/IJCIS.2017.10009287}, author = {Cristina Alcaraz} } @article {Alcaraz2017COSE, title = {Resilient Interconnection in Cyber-Physical Control Systems}, journal = {Computers \& Security}, volume = {71}, year = {2017}, month = {11/2017}, pages = {2-14}, publisher = {Elsevier}, abstract = {

Secure interconnection between multiple cyber-physical systems has become a\ fundamental requirement in many critical infrastructures, where security may be\ centralized in a few nodes of the system. These nodes could, for\ example, have\ the mission of addressing the authorization services required for access in highlyrestricted\ remote substations. For this reason, the main aim of this paper is to unify\ all these features, together with the resilience measures so as to provide control\ at all times under a limited access in the field and avoid congestion. Concretely,\ we present here an optimal reachability-based restoration approach, capable of\ restoring the structural control in linear times taking into account: structural controllability,\ the supernode theory, the good practices of the IEC-62351 standard\ and the contextual conditions. For context management, a new attribute is specified\ to provide a more complete authorization service based on a practical policy,\ role and attribute-based access control (PBAC + RBAC + ABAC). To validate\ the approach, two case studies are also discussed under two strategic adversarial\ models.

}, issn = {0167-4048}, doi = {https://doi.org/10.1016/j.cose.2017.03.004}, url = {http://www.sciencedirect.com/science/article/pii/S0167404817300573}, author = {Cristina Alcaraz and Javier Lopez and Kim-Kwang Raymond Choo} } @incollection {1603, title = {Secure Interoperability in Cyber-Physical Systems}, booktitle = {Security Solutions and Applied Cryptography in Smart Grid Communications, IGI Global, USA}, year = {2017}, pages = {137-158}, publisher = { IGI Global}, organization = { IGI Global}, chapter = {8}, address = {USA}, abstract = {

Transparency in control transactions under a secure network architecture is a key topic that must be discussed when aspects related to interconnection between heterogeneous cyber-physical systems (CPSs) arise. The interconnection of these systems can be addressed through an enforcement policy system responsible for managing access control according to the contextual conditions. However, this architecture is not always adequate to ensure a rapid interoperability in extreme crisis situations, and can require an interconnection strategy that permits the timely authorized access from anywhere at any time. To do this, a set of interconnection strategies through the Internet must be studied to explore the ability of control entities to connect to the remote CPSs and expedite their operations, taking into account the context conditions. This research constitutes the contribution of this chapter, where a set of control requirements and interoperability properties are identified to discern the most suitable interconnection strategies.

}, keywords = {authentication, authorization, Control Access, Control systems, cyber-physical systems, Internet of Things, Interoperability, Secure Interconnection}, isbn = {9781522518297}, doi = {10.4018/978-1-5225-1829-7.ch008}, author = {Cristina Alcaraz and Javier Lopez} } @inproceedings {1600, title = {Selecting Privacy Solutions to Prioritise Control in Smart Metering Systems}, booktitle = {The 11th International Conference on Critical Information Infrastructures Security}, volume = {10242}, year = {2017}, pages = {176-188}, abstract = {

The introduction of the Smart Grid brings with it several benefits to society, because its bi-directional communication allows both users and utilities to have better control over energy usage. However, it also has some privacy issues with respect to the privacy of the customers when analysing their consumption data. In this paper we review the main privacy-preserving techniques that have been proposed and compare their efficiency, to accurately select the most appropriate ones for undertaking control operations. Both privacy and performance are essential for the rapid adoption of Smart Grid technologies.

}, keywords = {and Metering, Control, Data privacy, Smart Grid}, author = {Juan E. Rubio and Cristina Alcaraz and Javier Lopez} } @inproceedings {nunez2017sistema, title = {Sistema de Acceso Delegado a Informaci{\'o}n Cifrada para Apache Hadoop}, booktitle = {III Jornadas Nacionales de Investigaci{\'o}n en Ciberseguridad}, year = {2017}, month = {06/2017}, pages = {174-175}, publisher = {URJC}, organization = {URJC}, address = {Madrid}, abstract = {

En este art{\'\i}culo presentamos un sistema que permite delegaci{\'o}n de acceso a informaci{\'o}n cifrada para Apache Hadoop, de forma segura y transparente al usuario. Para ello usamos t{\'e}cnicas criptogr{\'a}ficas avanzadas basadas en el recifrado delegado.\ Con este sistema, es posible almacenar en Hadoop los datos de forma cifrada y delegar de forma segura el acceso a los nodos de computaci{\'o}n.\ El funcionamiento es transparente ya que se integra con la capa del sistema de ficheros nativa HDFS.\ Adem{\'a}s, el recifrado delegado permite hacer rotaci{\'o}n de claves de cifrado de forma segura y r{\'a}pida.

}, keywords = {Big Data, Cryptography, Hadoop, proxy re-encryption}, isbn = {978-84-608-4659-8}, url = {http://hdl.handle.net/10115/14540}, author = {David Nu{\~n}ez and Isaac Agudo and Michael Egorov and MacLane Wilkison} } @inproceedings {Ifip15, title = {A4Cloud Workshop: Accountability in the Cloud}, booktitle = {IFIP Sumer School 2015 on Privacy and Identity Management. Time for a Revolution?}, volume = {476}, year = {2016}, month = {07/2016}, pages = {61-78}, publisher = {AICT Series, Springer}, organization = {AICT Series, Springer}, address = {Edinburgh (United Kingdon)}, author = {Carmen Fernandez-Gago and Siani Pearson and Michela D{\textquoteright}Errico and Rehab Alnemr and Tobias Pulls and Anderson Santana de Oliveira} } @article {nunez2016application, title = {On the Application of Generic CCA-Secure Transformations to Proxy Re-Encryption}, journal = {Security and Communication Networks}, volume = {9}, year = {2016}, month = {08/2016}, pages = {1769-1785}, publisher = {Wiley}, abstract = {

Several generic methods exist for achieving chosen-ciphertext attack (CCA)-secure public-key encryption schemes from weakly secure cryptosystems, such as the Fujisaki{\textendash}Okamoto and REACT transformations. In the context of proxy re-encryption (PRE), it would be desirable to count on analogous constructions that allow PRE schemes to achieve better security notions. In this paper, we study the adaptation of these transformations to proxy re-encryption and find both negative and positive results. On the one hand, we show why it is not possible to directly integrate these transformations with weakly secure PRE schemes because of general obstacles coming from both the constructions themselves and the security models, and we identify 12 PRE schemes that exhibit these problems. On the other hand, we propose an extension of the Fujisaki{\textendash}Okamoto transformation for PRE, which achieves a weak form of CCA security in the random oracle model, and we describe the sufficient conditions for applying it

}, issn = {1939-0114}, doi = {10.1002/sec.1434}, author = {David Nu{\~n}ez and Isaac Agudo and Javier Lopez} } @inproceedings {1585, title = {Dynamic Restoration in Interconnected RBAC-based Cyber-Physical Control Systems}, booktitle = {Proceedings of the 13th International Joint Conference on e-Business and Telecommunications (SECRYPT 2016)}, year = {2016}, month = { 2016}, pages = {19-27}, address = {Lisboa}, abstract = {

Increasingly, automatic restoration is an indispensable security measure in control systems (e.g. those used in\ critical infrastructure sectors) due to the importance of ensuring the functionality of monitoring infrastructures.\ Modernizing the interconnection of control systems to provide interoperability between different networks, at\ a low cost, is also a critical requirement in control systems. However, automated recovery mechanisms are\ currently costly, and ensuring interoperability particularly at a low cost remains a topic of scientific challenge.\ This is the gap we seek to address in this paper. More specifically, we propose a restoration model for interconnected\ contexts, taking into account the theory of supernode and structural controllability, as well as the\ recommendations given by the IEC-62351-8 standard (which are mainly based on the implementation of a\ role-based access control system).

}, isbn = {978-989-758-196-0}, doi = {10.5220/0005942000190027}, author = {Cristina Alcaraz and Javier Lopez and Kim-Kwang Raymond Choo} } @inproceedings {nunez2016nuevas, title = {Nuevas nociones de seguridad y transformaciones gen{\'e}ricas para criptosistemas de recifrado delegado}, booktitle = {XIV Reuni{\'o}n Espa{\~n}ola sobre Criptolog{\'\i}a y Seguridad de la Informaci{\'o}n}, year = {2016}, month = {10/2016}, pages = {174-179}, address = {Mah{\'o}n, Menorca, Islas Baleares}, abstract = {

El recifrado delegado (proxy re-encryption) es un tipo de cifrado de clave p{\'u}blica que permite delegar la capacidad de transformar textos cifrados de una clave p{\'u}blica a otra, sin que se pueda obtener ninguna informaci{\'o}n sobre el mensaje subyacente. Por este motivo, representa un candidato natural para construir mecanismos criptogr{\'a}ficos de control de acceso. En este art{\'\i}culo estudiamos algunos de los problemas de seguridad de este tipo de criptosistemas. En primer lugar, examinamos las nociones de seguridad e identificamos una nueva familia param{\'e}trica de modelos de ataque, que considera la disponibilidad tanto del or{\'a}culo de descifrado como de recifrado. En segundo lugar, estudiamos la aplicabilidad de transformaciones gen{\'e}ricas para mejorar la seguridad, centr{\'a}ndonos en la transformaci{\'o}n Fujisaki-Okamoto, y formulamos las condiciones que nos permiten aplicarla.

}, keywords = {proxy re-encryption}, isbn = { 978-84-608-9470-4}, author = {David Nu{\~n}ez and Isaac Agudo and Javier Lopez} } @article {alcaraz2016POL, title = {Policy Enforcement System for Secure Interoperable Control in Distributed Smart Grid Systems}, journal = {Journal of Network and Computer Applications}, volume = {59}, year = {2016}, month = {01/2016}, pages = {301{\textendash}314}, publisher = {Elsevier}, abstract = {

Interoperability of distributed systems in charge of monitoring and maintaining the different critical domains belonging to Smart Grid scenarios comprise the central topic of this paper. Transparency in control transactions under a secure and reliable architecture is the aim of the policy enforcement system proposed here. The approach is based on the degree of observation of a context and on the role-based access control model defined by the IEC-62351-8 standard. Only authenticated and authorised entities are able to take control of those distributed elements (e.g., IEC-61850 objects) located at distant geographical locations and close to the critical infrastructures (e.g., substations). To ensure the effectiveness of the approach, it is built on graphical-theoretical formulations corresponding to graph theory, where it is possible to illustrate power control networks through power-law distributions whose monitoring relies on structural controllability theory. The interconnection of these distributions is subject to a network architecture based on the concept of the supernode where the interoperability depends on a simple rule-based expert system. This expert system focuses not only on accepting or denying access, but also on providing the means to attend to extreme situations, avoiding, as much as possible, the overloading of the communication. Through one practical study we also show the functionalities of the approach and the benefits that the authorisation itself can bring to the interoperability.\ 

}, issn = {1084-8045}, author = {Cristina Alcaraz and Javier Lopez and Stephen Wolthusen} } @inproceedings {1598, title = {Safeguarding Structural Controllability in Cyber-Physical Control Systems}, booktitle = {The 21st European Symposium on Research in Computer Security (ESORICS 2016)}, volume = {9879}, year = {2016}, pages = {471-489}, publisher = {Springer}, organization = {Springer}, address = {Crete, Greece}, abstract = {

Automatic restoration of control wireless networks based on dynamic\ cyber-physical systems has become a hot topic in recent years, since most of their\ elements tend to have serious vulnerabilities that may be exploited by attackers.\ In fact, any exploitation may rapidly extend to the entire control network due to\ its problem of non-locality, where control properties of a system and its structural\ controllability can disintegrate over time. Unfortunately, automated self-healing\ processes may become costly procedures in which the reliability of the strategies\ and the time-critical of any recovery of the control can become key factors to\ re-establish the control properties in due time. This operational need is precisely\ the aim of this paper, in which four reachability-based recovery strategies from\ a thereotical point of view are proposed so as to find the best option/s in terms\ of optimization, robustness and complexity. To do this, new definitions related to\ structural controllability in relation to the type of distribution of the network and\ its control load capacity are given in this paper, resulting in an interesting practical\ study.

}, keywords = {Control systems, cyber-physical systems, restoration, self-healing, structural controllability}, isbn = {978-3-319-45741-3}, author = {Cristina Alcaraz and Javier Lopez} } @inproceedings {agudo2016technique, title = {A Technique for Enhanced Provision of Appropriate Access to Evidence across Service Provision Chains}, booktitle = {10th International IFIP Summer School on Privacy and Identity Management}, year = {2016}, pages = {187-204}, abstract = {

Transparency and verifiability are necessary aspects of accountability, but care needs to be taken that auditing is done in a privacy friendly way. There are situations where it would be useful for certain actors to be able to make restricted views within service provision chains on accountability evidence, including logs, available to other actors with specific governance roles. For example, a data subject or a Data Protection Authority (DPA) might want to authorize an accountability agent to act on their behalf, and be given access to certain logs in a way that does not compromise the privacy of other actors or the security of involved data processors. In this paper two cryptographic-based techniques that may address this issue are proposed and assessed.

}, isbn = {978-3-319-41762-2}, doi = {10.1007/978-3-319-41763-9_13}, author = {Isaac Agudo and Ali El Kaafarani and David Nu{\~n}ez and Siani Pearson} } @article {cazorla2015b, title = {Awareness and Reaction Strategies for Critical Infrastructure Protection}, journal = {Computers and Electrical Engineering}, volume = {47}, year = {2015}, pages = {299-317}, publisher = {Elsevier}, abstract = {

Current Critical Infrastructures (CIs) need intelligent automatic active reaction mechanisms to protect their critical processes against cyber attacks or system anomalies, and avoid the disruptive consequences of cascading failures between interdependent and interconnected systems. In this paper we study the Intrusion Detection, Prevention and Response Systems (IDPRS) that can offer this type of protection mechanisms, their constituting elements and their applicability to critical contexts. We design a methodological framework determining the essential elements present in the IDPRS, while evaluating each of their sub-components in terms of adequacy for critical contexts. We review the different types of active and passive countermeasures available, categorizing them and assessing whether or not they are suitable for Critical Infrastructure Protection (CIP). Through our study we look at different reaction systems and learn from them how to better create IDPRS solutions for CIP.\ 

}, keywords = {Control systems, Countermeasures, Critical Infrastructure Protection, Intrusion Detection and Response Systems}, issn = {0045-7906}, doi = {10.1016/j.compeleceng.2015.08.010}, author = {Lorena Cazorla and Cristina Alcaraz and Javier Lopez} } @inproceedings {931, title = {Context-Awareness using Anomaly-based Detectors for Smart Grid Domains}, booktitle = {9th International Conference on Risks and Security of Internet and Systems }, volume = {8924}, year = {2015}, month = {04/2015}, pages = {17-34}, publisher = {Springer International Publishing}, organization = {Springer International Publishing}, address = {Trento}, abstract = {

Anomaly-based detection applied in strongly interdependent systems, like Smart Grids, has become one of the most challenging research areas in recent years. Early detection of anomalies so as to detect and prevent unexpected faults or stealthy threats is attracting a great deal of attention from the scientific community because it offers potential solutions for context-awareness. These solutions can also help explain the conditions leading up\ to a given situation and help determine the degree of its severity. However, not all the existing approaches within the literature are equally effective in covering the needs of a particular scenario. It is necessary to explore the control requirements of the domains that comprise a Smart Grid, identify, and even select, those approaches according to these requirements and the intrinsic conditions related to the application context, such as technological heterogeneity and complexity. Therefore, this paper analyses the functional features of existing anomaly-based approaches so as to adapt them, according to the aforementioned conditions. The result of this investigation is a guideline for the construction of preventive solutions that will help improve the context-awareness in the control of Smart Grid domains in the near future.

}, keywords = {Context-Awareness, Control systems, Prevention, Smart Grid}, isbn = {978-3-319-17126-5}, doi = {10.1007/978-3-319-17127-2_2}, url = {http://link.springer.com/chapter/10.1007\%2F978-3-319-17127-2_2$\#$}, author = {Cristina Alcaraz and Lorena Cazorla and Gerardo Fernandez} } @article {alcaraz2015CRI, title = {Critical Infrastructure Protection: Requirements and Challenges for the 21st Century}, journal = {International Journal of Critical Infrastructure Protection (IJCIP)}, volume = {8}, year = {2015}, month = {01/2015}, pages = {53{\textendash}66}, publisher = {Elsevier Science}, abstract = {

Critical infrastructures play a vital role in supporting modern society. The reliability, performance, continuous operation, safety, maintenance and protection of critical infrastructures are national priorities for countries around the world. This paper explores the vulnerabilities and threats facing modern critical infrastructures with special emphasis on industrial control systems, and describes a number of protection measures. The paper also discusses some of the challenging areas related to critical infrastructure protection such as governance and security management, secure network architectures, self-healing, modeling and simulation, wide-area situational awareness, forensics and learning, and trust management and privacy.

}, keywords = {Challenges, Critical Infrastructure Protection, Requirements, Risk, SCADA Systems, security}, issn = {1874-5482}, doi = {http://dx.doi.org/10.1016/j.ijcip.2014.12.002}, url = {http://www.sciencedirect.com/science/article/pii/S1874548214000791}, author = {Cristina Alcaraz and Sherali Zeadally} } @inproceedings {alcaraz2013controla, title = {Multi-Round Attacks on Structural Controllability Properties for Non-Complete Random Graphs}, booktitle = {The 16th Information Security Conference (ISC)}, volume = {7807}, year = {2015}, month = {09/2015}, pages = {140{\textendash}151}, publisher = {Springer}, organization = {Springer}, address = {Springer International Publishing Switzerland}, abstract = {

\ The notion of controllability, informally the ability to force a system\ into a desired state in a finite time or number of steps, is most closely associated with control systems such as those used to maintain power networks and other critical infrastructures, but has wider relevance in distributed systems. It is clearly highly desirable to understand under which conditions attackers may be able to disrupt legitimate control, or to force overriding controllability themselves. Following recent results by Liu et al., there has been considerable interest also in graph-theoretical interpretation of Kalman controllability originally introduced by Lin, structural controllability. This permits the identification of sets of driver nodes with the desired state-forcing property, but determining such nodes\ is aW[2]-hard problem. To extract these nodes and represent the control relation, here we apply the POWER DOMINATING SET problem and investigate the effects of targeted iterative multiple-vertex removal. We report the impact that different attack strategies with multiple edge and vertex removal will have, based on underlying non-complete graphs, with an emphasis on power-law random graphs with different degree sequences.

}, doi = {10.1007/978-3-319-27659-5 10}, author = {Cristina Alcaraz and Estefania Etcheves Miciolino and Stephen Wolthusen} } @inproceedings {nunez2015ntrureencrypt, title = {NTRUReEncrypt: An Efficient Proxy Re-Encryption Scheme Based on NTRU}, booktitle = {10th ACM Symposium on Information, Computer and Communications Security (AsiaCCS)}, year = {2015}, month = {04/2015}, pages = {179-189}, abstract = {

The use of alternative foundations for constructing more secure and efficient cryptographic schemes is a topic worth exploring. In the case of proxy re-encryption, the vast majority of schemes are based on number theoretic problems such as the discrete logarithm. In this paper we present NTRUReEncrypt, a new bidirectional and multihop proxy re-encryption scheme based on NTRU, a widely known lattice-based cryptosystem. We provide two versions of our scheme: the first one is based on the conventional NTRU encryption scheme and, although it lacks a security proof, remains as efficient as its predecessor; the second one is based on a variant of NTRU proposed by Stehl{\'e} and Steinfeld, which is proven CPA-secure under the hardness of the Ring-LWE problem. To the best of our knowledge, our proposals are the first proxy re-encryption schemes to be based on the NTRU primitive. In addition, we provide experimental results to show the efficiency of our proposal, as well as a comparison with previous proxy re-encryption schemes, which confirms that our first scheme outperforms the rest by an order of magnitude.

}, isbn = {978-1-4503-3245-3}, doi = {10.1145/2714576.2714585}, author = {David Nu{\~n}ez and Isaac Agudo and Javier Lopez} } @inproceedings {nunez2015parametric, title = {A Parametric Family of Attack Models for Proxy Re-Encryption}, booktitle = {28th IEEE Computer Security Foundations Symposium}, series = {CSF{\textquoteright}15}, year = {2015}, month = {07/2015}, pages = {290-301}, publisher = {IEEE Computer Society}, organization = {IEEE Computer Society}, address = {Verona, Italy}, abstract = {

Proxy Re-Encryption (PRE) is a type of Public-Key Encryption (PKE) which provides an additional re-encryption functionality. Although PRE is inherently more complex than PKE, attack models for PRE have not been developed further than those inherited from PKE. In this paper we address this gap and define a parametric family of attack models for PRE, based on the availability of both the decryption and re-encryption oracles during the security game. This family enables the definition of a set of intermediate security notions for PRE that ranges from {\textquoteleft}{\textquoteleft}plain{\textquoteright}{\textquoteright} IND-CPA to {\textquoteleft}{\textquoteleft}full{\textquoteright}{\textquoteright} IND-CCA. We analyze some relations among these notions of security, and in particular, the separations that arise when the re-encryption oracle leaks re-encryption keys. In addition, we discuss which of these security notions represent meaningful adversarial models for PRE. Finally, we provide an example of a recent {\textquoteleft}{\textquoteleft}CCA1- secure{\textquoteright}{\textquoteright} scheme from PKC 2014 whose security model does not capture chosen-ciphertext attacks through re-encryption and for which we describe an attack under a more realistic security notion. This attack emphasizes the fact that PRE schemes that leak re-encryption keys cannot achieve strong security notions.

}, isbn = { 978-1-4673-7538-2}, issn = {1063-6900}, doi = {10.1109/CSF.2015.27}, author = {David Nu{\~n}ez and Isaac Agudo and Javier Lopez} } @incollection {nunez15privacy, title = {Privacy-Preserving Identity Management as a Service}, booktitle = {Accountability and Security in the Cloud}, series = {Lecture Notes in Computer Science}, volume = {8937}, year = {2015}, pages = {114-125}, publisher = {Springer International Publishing}, organization = {Springer International Publishing}, abstract = {

In this paper we tackle the problem of privacy and confidentiality in Identity Management as a Service (IDaaS). The adoption of cloud computing technologies by organizations has fostered the externalization of the identity management processes, shaping the concept of Identity Management as a Service. However, as it has happened to other cloud-based services, the cloud poses serious risks to the users, since they lose the control over their data. As part of this work, we analyze these concerns and present a model for privacy-preserving IDaaS, called BlindIdM, which is designed to provide data privacy protection through the use of cryptographic safeguards.

}, keywords = {Cloud Computing, Cryptography, Identity Management as a Service, privacy}, isbn = {978-3-319-17198-2}, doi = {10.1007/978-3-319-17199-9_5}, url = {http://dx.doi.org/10.1007/978-3-319-17199-9_5}, author = {David Nu{\~n}ez and Isaac Agudo and Javier Lopez}, editor = {Massimo Felici and Carmen Fernandez-Gago} } @proceedings {1591, title = {Proceedings of the 12th ACM Symposium on Performance Evaluation of Wireless Ad Hoc, Sensor, \& Ubiquitous Networks, PE-WASUN 2015}, journal = {12th ACM Symposium on Performance Evaluation of Wireless Ad Hoc, Sensor, \& Ubiquitous Networks, PE-WASUN 2015}, year = {2015}, publisher = {ACM}, address = {Cancun, Mexico}, isbn = {978-1-4503-3759-5}, url = {http://dblp2.uni-trier.de/db/conf/pe-wasun/pe-wasun2015.html}, author = {M{\'o}nica Aguilar-Igartua and Carolina Tripp Barba and Cristina Alcaraz} } @article {lorena2015c, title = {A Three-Stage Analysis of IDS for Critical Infrastructures}, journal = {Computers \& Security}, volume = {55}, number = {November}, year = {2015}, pages = {235-250}, publisher = {Elsevier}, abstract = {

The correct operation of Critical Infrastructures (CIs) is vital for the well being of society, however these complex systems are subject to multiple faults and threats every day. International organizations around the world are alerting the scientific community to the need for protection of CIs, especially through preparedness and prevention mechanisms. One of the main tools available in this area is the use of Intrusion Detection Systems (IDSs). However, in order to deploy this type of component within a CI, especially within its Control System (CS), it is necessary to verify whether the characteristics of a given IDS solution are compatible with the special requirements and constraints of a critical environment. In this paper, we carry out an extensive study to determine the requirements imposed by the CS on the IDS solutions using the Non-Functional Requirements (NFR) Framework. The outcome of this process are the abstract properties that the IDS needs to satisfy in order to be deployed within a CS, which are refined through the identification of satisficing techniques for the NFRs. To provide quantifiable measurable evidence on the suitability of the IDS component for a CI, we broaden our study using the Goal Question Metric (GQM) approach to select a representative set of metrics. A requirements model, refined with satisficing techniques and sets of metrics which help assess, in the most quantifiable way possible, the suitability and performance of a given IDS solution for a critical scenario, constitutes the results of our analysis.

}, issn = {0167-4048}, author = {Lorena Cazorla and Cristina Alcaraz and Javier Lopez} } @inproceedings {1516, title = {Tools for Cloud Accountability: A4Cloud Tutorial}, booktitle = {9th IFIP Summer School on Privacy and Identity Management for the Future Internet in the Age of Globalisation}, volume = {457}, year = {2015}, pages = {219-236}, publisher = {Springer IFIP AICT}, organization = {Springer IFIP AICT}, address = {Patras (Greece)}, abstract = {

Cloud computing is becoming a key IT infrastructure technology being adopted progressively by companies and users. Still, there are issues and uncertainties surrounding its adoption, such as security and how users data is dealt with that require attention from developers, researchers, providers and users. The A4Cloud project tries to help solving the problem of accountability in the cloud by providing tools that support the process of achieving accountability. This paper presents the contents of the first A4Cloud tutorial. These contents include basic concepts and tools developed within the project. In particular, we will review how metrics can aid the accountability process and some of the tools that the A4Cloud project will produce such as the Data Track Tool (DTT) and the Cloud Offering Advisory Tool (COAT).

}, isbn = {978-3-319-18620-7}, issn = {978-3-319-18621-4}, doi = {10.1007/978-3-319-18621-4_15}, author = {Carmen Fernandez-Gago and Vasilis Tountopoulos and Simone Fischer-H{\"u}bner and Rehab Alnemr and David Nu{\~n}ez and Julio Angulo and Tobias Pulls and Theo Koulouris} } @article {nunez2014blindidm, title = {BlindIdM: A Privacy-Preserving Approach for Identity Management as a Service}, journal = {International Journal of Information Security}, volume = {13}, year = {2014}, pages = {199-215}, publisher = {Springer}, abstract = {

Identity management is an almost indispensable component of today{\textquoteright}s organizations and companies, as it plays a key role in authentication and access control; however, at the same time it is widely recognized as a costly and time-consuming task. The advent of cloud computing technologies, together with the promise of flexible, cheap and efficient provision of services, has provided the opportunity to externalize such a common process, shaping what has been called Identity Management as a Service (IDaaS). Nevertheless, as in the case of other cloud-based services, IDaaS brings with it great concerns regarding security and privacy, such as the loss of control over the outsourced data. In this paper we analyze these concerns and propose BlindIdM, a model for privacy-preserving IDaaS with a focus on data privacy protection. In particular, we describe how a SAML-based system can be augmented to employ proxy re-encryption techniques for achieving data con dentiality with respect to the cloud provider, while preserving the ability to supply the identity service. This is an innovative contribution to both the privacy and identity management landscapes.

}, issn = {1615-5262}, doi = {10.1007/s10207-014-0230-4}, author = {David Nu{\~n}ez and Isaac Agudo} } @article {CSI13, title = {Building Trust from Context Similarity Measures}, journal = {Computer Standards \& Interfaces, Special Issue on Security in Information Systems}, volume = {36}, year = {2014}, pages = {792-800}, publisher = {Elsevier}, abstract = {

\ Trust is an essential feature of any system where entities have to\ collaborate among them. Trust can assist entities making decisions\ about what is the best entity for establishing a certain collaboration.\ It would be desirable to simulate behaviour of users as in social environments\ where they tend to establish relationships or to trust users\ who have common interests or share some of their opinions, i.e., users\ who are similar to them to some extent. Thus, in this paper we first\ introduce the concept of context similarity among entities and from it\ we derive a similarity network which can be seen as a graph. Based\ on this similarity network we dene a trust model that allows us also\ to establish trust along a path of entities. A possible applications of\ our model are proximity-based trust establishment. We validate our model in this scenario.

}, issn = {0920-5489}, doi = {10.1016/j.csi.2013.12.012}, author = {Carmen Fernandez-Gago and Isaac Agudo and Javier Lopez} } @inproceedings {nunez2014delegated, title = {Delegated Access for Hadoop Clusters in the Cloud}, booktitle = {IEEE International Conference on Cloud Computing Technology and Science (CloudCom 2014)}, year = {2014}, month = {12/2014}, pages = {374-379}, publisher = {IEEE}, organization = {IEEE}, address = {Singapore}, abstract = {

Among Big Data technologies, Hadoop stands out for its capacity to store and process large-scale datasets. However, although Hadoop was not designed with security in mind, it is widely used by plenty of organizations, some of which have strong data protection requirements. Traditional access control solutions are not enough, and cryptographic solutions must be put in place to protect sensitive information. In this paper, we describe a cryptographically-enforced access control system for Hadoop, based on proxy re-encryption. Our proposed solution fits in well with the outsourcing of Big Data processing to the cloud, since information can be stored in encrypted form in external servers in the cloud and processed only if access has been delegated. Experimental results show that the overhead produced by our solution is manageable, which makes it suitable for some applications.

}, isbn = {978-1-4799-4093-6}, doi = {10.1109/CloudCom.2014.50}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=7037691}, author = {David Nu{\~n}ez and Isaac Agudo and Javier Lopez} } @article {alcaraz2013a, title = {Diagnosis Mechanism for Accurate Monitoring in Critical Infrastructure Protection}, journal = {Computer Standards \& Interfaces}, volume = {36}, year = {2014}, pages = {501-512}, publisher = {Elsevier}, abstract = {

\ Situational awareness for critical infrastructure protection, such as for energy\ control systems, has become a topic of interest in recent years. Despite attempts\ to address this area of research, more progress is still necessary to find attractive solutions that help bring about prevention and response at all times from\ anywhere and at any time. Given this need, we therefore propose in this paper, a smart mechanism able to offer a wide-area situational awareness with the\ ability to: (i) Control the real state of the observed infrastructure, (ii) respond\ to emergency situations and (iii) assess the degree of \ ccuracy of the entire\ control system. To address these aspects, the mechanism is based on a hierarchical configuration of industrial sensors for control, the ISA100.11a standard\ for the prioritization and alarm management, and the F-Measure technique to\ study the level of accuracy of a sensor inside a neighbourhood. As proof of the\ functionality and feasibility of the mechanism for critical contexts, a software\ application implemented in nesC and Java is also presented in this paper.

}, issn = {0920-5489}, doi = {10.1016/j.csi.2013.10.002}, author = {Cristina Alcaraz and Javier Lopez} } @proceedings {421, title = {Procedings of the 10th European Workshop on Public Key Infrastructures, Services and Applications}, journal = {10th European Workshop on Public Key Infrastructures, Services and Applications}, volume = {8341}, year = {2014}, publisher = {Springer}, edition = {LNCS}, isbn = {978-3-642-53996-1}, doi = {10.1007/978-3-642-53997-8}, author = {Sokratis Katsikas and Isaac Agudo} } @inproceedings {430, title = {Recovery of Structural Controllability for Control Systems}, booktitle = {Eighth IFIP WG 11.10 International Conference on Critical Infrastructure Protection, SRI International, Arlington, Virginia, USA }, volume = {441}, year = {2014}, pages = {47-63}, publisher = {Springer}, organization = {Springer}, address = {Arlington, Virginia, USA}, abstract = {

Fundamental problems in control systems theory are controllability and observability, and designing control systems so that these properties are satisfied or approximated sufficiently. However, it is prudent to as- sume that an attacker will not only be able to subvert measurements but also control the system. Moreover, an advanced adversary with an understanding of the control system may seek to take over control of the entire system or parts thereof, or deny the legitimate operator this capability. The effectiveness of such attacks has been demonstrated in previous work. Indeed, these attacks cannot be ruled out given the likely existence of unknown vulnerabilities, increasing connectivity of nominally air-gapped systems and supply chain issues. The ability to rapidly recover control after an attack has been initiated and to detect an adversary{\textquoteright}s presence is, therefore, critical. This paper focuses on the problem of structural controllability, which has recently attracted substantial attention through the equivalent problem of the power dom- inating set introduced in the context of electrical power network control. However, these problems are known to be NP-hard with poor approx- imability. Given their relevance to many networks, especially power networks, this paper studies strategies for the efficient restoration of controllability following attacks and attacker-defender interactions in power-law networks.\ 

}, keywords = {Control systems, power domination, resilience, structural controllability}, isbn = {978-3-662-45354-4}, issn = {1868-4238}, doi = {http://dx.doi.org/10.1007/978-3-662-45355-1_4}, author = {Cristina Alcaraz and Stephen Wolthusen} } @article {alcaraz2013b, title = {WASAM: A Dynamic Wide-Area Situational Awareness Model for Critical Domains in Smart Grids}, journal = {Future Generation Computer Systems}, volume = {30}, year = {2014}, pages = {146-154}, publisher = {Elsevier}, abstract = {

Control from anywhere and at anytime is nowadays a matter of paramount importance in\ critical systems. This is the case of the Smart Grid and its domains which should be monitored through\ intelligent and dynamic mechanisms able to anticipate, detect and respond before disruptions arise\ within the system. Given this fact and its importance for social welfare and the economy, a model for\ wide-area situational awareness is proposed in this paper. The model is based on a set of current\ technologies such as the wireless sensor networks, the ISA100.11a standard and cloud-computing\ together with a set of high-level functional services. These services include global and local support for\ prevention through a simple forecast scheme, detection of anomalies in the observation tasks,\ response to incidents, tests of accuracy and maintenance, as well as recovery of states and control in\ crisis situations.

}, keywords = {Cloud Computing, Critical Infrastructure Protection, Smart Grid, Wide-Area Situational Awareness, wireless sensor networks}, issn = {0167-739X}, doi = {https://doi.org/10.1016/j.future.2013.06.030}, author = {Cristina Alcaraz and Javier Lopez} } @article {1762, title = {Critical Control System Protection in the 21st Century: Threats and Solutions}, journal = {IEEE Computer}, volume = {46}, number = {10}, year = {2013}, month = {2013}, pages = {74 - 83}, publisher = {IEEE Computer Society}, abstract = {

Information systems, networks, and technologies have become an integral part of modern critical control systems that manage many of today\&$\#$x2019;s critical infrastructures. The continuous operation, maintenance, and protection of critical infrastructures have become a high national priority for governments around the world because our society heavily depends on them for most of our daily activities (travel, power usage, banking transactions, telecommunications, etc) and safety. It is therefore critical that these infrastructures have to be protected from potential accidental incidents or cyberattacks. We present the fundamental architectural components of critical control systems which manage most critical infrastructures. We identify some of the vulnerabilities and threats to modern critical control systems followed by protection solutions that can be deployed to mitigate attacks exploiting these vulnerabilities.

}, issn = {0018-9162}, doi = {10.1109/MC.2013.69}, author = {Cristina Alcaraz and S. Zeadally} } @article {alcaraz2013ecn, title = {FACIES: online identification of Failure and Attack on interdependent Critical InfrastructurES}, journal = {European CIIP Newsletter}, volume = {7}, year = {2013}, month = {Nov 2013}, pages = {11-13}, publisher = {European_CIIP_Newsletter}, abstract = {

\ FACIES aims to protect water treatment systems and their control systems against accidental or intentional incidents such as failures, anomalies and cyber-attacks with a particular emphasis on stealth attacks.

}, issn = {NONE}, author = {Cristina Alcaraz and Javier Lopez} } @inproceedings {nunez2013leveraging, title = {Leveraging Privacy in Identity Management as a Service through Proxy Re-Encryption}, booktitle = {Ph.D Symposium of the European Conference on Service-Oriented and Cloud Computing (ESOCC) 2013}, year = {2013}, month = {September 2013}, address = {M{\'a}laga, Spain}, abstract = {

The advent of cloud computing has provided the opportunity to externalize the identity management processes, shaping what has been called Identity Management as a Service (IDaaS). However, as in the case of other cloud-based services, IDaaS brings with it great concerns regarding security and privacy, such as the loss of control over the outsourced data. As part of this PhD thesis, we analyze these concerns and propose BlindIdM, a model for privacy-preserving IDaaS with a focus on data privacy protection through the use of proxy re-encryption.

}, author = {David Nu{\~n}ez and Isaac Agudo and Javier Lopez} } @inproceedings {alcaraz2011critis, title = {PDR: A Prevention, Detection and Response Mechanism for Anomalies in Energy Control Systems}, booktitle = {7th International Conference on Critical Information Infrastructures Security (CRITIS 2012)}, volume = {7722}, year = {2013}, pages = {22{\textendash}33}, address = {Lillehammer, Norway}, abstract = {

\ Prevention, detection and response are nowadays considered to be three priority topics for protecting critical infrastructures, such as energy control systems. Despite attempts to address these current issues, there is still a particular lack of investigation in these areas, and in particular in dynamic and automatic proactive solutions. In this paper we propose a mechanism, which is called PDR, with the capability of anticipating anomalies, detecting anomalous behaviours and responding to them in a timely manner. PDR is based on a conglomeration of technologies and on a set of essential components with the purpose of offering situational awareness irrespective of where the system is located. In addition, the mechanism can also compute its functional capacities by evaluating its efficacy and precision in the prediction and detection of disturbances. With this, the entire system is able to know the real reliability of its services and its activity in remote substations at all times.

}, author = {Cristina Alcaraz and Meltem Sonmez} } @article {agudo2013, title = {A Privacy-Aware Continuous Authentication Scheme for Proximity-Based Access Control}, journal = {Computers \& Security}, volume = {39 (B)}, year = {2013}, month = {11/2013}, pages = {117-126}, publisher = {Elsevier}, abstract = {

Continuous authentication is mainly associated with the use of biometrics to guarantee that a resource is being accessed by the same user throughout the usage period. Wireless devices can also serve as a supporting technology for continuous authentication or even as a complete alternative to biometrics when accessing proximity-based services. In this paper we present the implementation of a secure, non-invasive continuous authentication scheme supported by the use of Wearable Wireless Devices (WWD), which allow users to gain access to proximity-based services while preserving their privacy. Additionally we devise an improved scheme that circumvents some of the limitations of our implementation.

}, issn = {0167-4048}, doi = {10.1016/j.cose.2013.05.004}, author = {Isaac Agudo and Ruben Rios and Javier Lopez} } @article {1752, title = {Security of Industrial Sensor Network-based Remote Substations in the context of the Internet of Things}, journal = {Ad Hoc Networks}, volume = {11}, year = {2013}, month = {2013}, pages = {1091{\textendash}1104}, publisher = {Elsevier}, abstract = {

The main objective of remote substations is to provide the central system with sensitive information from critical infrastructures, such as generation, distribution or transmission power systems. Wireless sensor networks have been recently applied in this particular context due to their attractive services and inherent benefits, such as simplicity, reliability and cost savings. However, as the number of control and data acquisition systems that use the Internet infrastructure to connect to substations increases, it is necessary to consider what connectivity model the sensor infrastructure should follow: either completely isolated from the Internet or integrated with it as part of the Internet of Things paradigm. This paper therefore addresses this question by providing a thorough analysis of both security requirements and infrastructural requirements corresponding to all those TCP/IP integration strategies that can be applicable to networks with constrained computational resources.

}, keywords = {Industrial Control Networks, Internet of Things, Supervisory Control and Data Acquisition (SCADA) Systems, The Internet, wireless sensor networks}, issn = {1570-8705}, doi = {http://dx.doi.org/10.1016/j.adhoc.2012.12.001}, author = {Cristina Alcaraz and Rodrigo Roman and Pablo Najera and Javier Lopez} } @article {1770, title = {Smart Control of Operational Threats in Control Substations}, journal = {Computers \& Security}, volume = {38}, year = {2013}, month = {OCT 2013}, pages = {14-27}, publisher = {Elsevier}, abstract = {

Any deliberate or unsuitable operational action in control tasks of critical infrastructures, such as energy generation, transmission and distribution systems that comprise sub-domains of a Smart Grid, could have a significant impact on the digital economy: without energy, the digital economy cannot live. In addition, the vast majority of these types of critical systems are configured in isolated locations where their control depends on the ability of a few, supposedly trustworthy, human operators. However, this assumption of reliabilty is not always true. Malicious human operators (criminal insiders) might take advantage of these situations to intentionally manipulate the critical nature of the underlying infrastructure. These criminal actions could be not attending to emergency events, inadequately responding to incidents or trying to alter the normal behaviour of the system with malicious actions. For this reason, in\ this paper we propose a smart response mechanism that controls human operators{\textquoteright} operational threats at all times. Moreover, the design of this mechanism allows the system to be able to not only evaluate by itself, the situation of a particular scenario but also to take control when areas are totally unprotected and/or isolated. The response mechanism, which is based on Industrial Wireless Sensor Networks (IWSNs) for the constant monitoring of observed critical\ infrastructures, on reputation for controlling human operators{\textquoteright} actions, and on the ISA100.11a standard for alarm management, has been implemented and simulated to evaluate its feasibility for critical contexts.

}, keywords = {Digital Economy, Energy Control Systems, Reputation, security, Smart grids, wireless sensor networks}, issn = {0167-4048}, doi = {https://doi.org/10.1016/j.cose.2013.03.013}, url = {http://www.sciencedirect.com/science/article/pii/S0167404813000588}, author = {Javier Lopez and Cristina Alcaraz and Rodrigo Roman} } @inproceedings {1810, title = {Structural Controllability of Networks for Non-Interactive Adversarial Vertex Removal}, booktitle = {8th International Conference on Critical Information Infrastructures Security}, volume = {8328}, year = {2013}, pages = {120-132}, publisher = {Springer}, organization = {Springer}, address = {Amsterdam, The Netherlands}, abstract = {

The problem of controllability of networks arises in a number of different\ domains, including in critical infrastructure systems where control must be\ maintained continuously. Recent work by Liu et al. has renewed interest in the\ seminal work by Lin on structural controllability, providing a graph-theoretical\ interpretation. This allows the identification of driver nodes capable of forcing the\ system into a desired state, which implies an obvious target for attackers wishing\ to disrupt the network control. Several methods for identifying driver nodes\ exist, but require undesirable computational complexity. In this paper, we therefore\ investigate the ability to regain or maintain controllability in the presence\ of adversaries able to remove vertices and implicit edges of the controllability\ graph. For this we rely on the POWER DOMINATING SET (PDS) formulation for\ identifying the control structure and study different attack strategies for multiple\ network models. As the construction of a PDS for a given graph is not unique,\ we further investigate different strategies for PDS construction, and provide a\ simulative evaluation.

}, issn = {0302-9743}, doi = {http://link.springer.com/chapter/10.1007\%2F978-3-319-03964-0_11}, author = {Cristina Alcaraz and Estefania Etcheves Miciolino and Stephen Wolthusen} } @inproceedings {1805, title = {Towards Automatic Critical Infrastructure Protection through Machine Learning}, booktitle = {8th International Conference on Critical Information Infrastructures Security}, volume = {8328}, year = {2013}, pages = {197-203}, publisher = {Springer}, organization = {Springer}, address = {Amsterdam, The Netherlands}, abstract = {

Critical Infrastructure Protection (CIP) faces increasing challenges in number and in sophistication, which makes vital to provide new forms of protection to face every day{\textquoteright}s threats. In order to make such protection holistic, covering all the needs of the systems from the point of view of security, prevention aspects and situational awareness should be considered. Researchers and Institutions stress the need of providing intelligent and automatic solutions for\ protection, calling our attention to the need of providing Intrusion Detection Systems (IDS) with intelligent active reaction capabilities. In this paper, we support the need of automating the processes implicated in the IDS solutions of the critical infrastructures and theorize that the introduction of Machine Learning (ML) techniques in IDS will be helpful for implementing automatic adaptable solutions\ capable of adjusting to new situations and timely reacting in the face of threats and anomalies. To this end, we study the different levels of automation that the IDS can implement, and outline a methodology to endow critical scenarios with preventive automation. Finally, we analyze current solutions presented in the literature and contrast them against the proposed methodology

}, issn = {0302-9743}, doi = {http://link.springer.com/chapter/10.1007\%2F978-3-319-03964-0_18}, author = {Lorena Cazorla and Cristina Alcaraz and Javier Lopez} } @inproceedings {moyano2013ifiptm, title = {Towards Trust-Aware and Self-Adaptive Systems}, booktitle = {7th IFIP WG 11.11 International Conference on Trust Management (IFIPTM 2013)}, series = {AICT}, volume = {401}, year = {2013}, month = {Jun 2013}, pages = {255-262}, publisher = {Springer}, organization = {Springer}, address = {Malaga}, abstract = {

The Future Internet (FI) comprises scenarios where many heterogeneous and dynamic entities must interact to provide services (e.g., sensors, mobile devices and information systems in smart city scenarios). The dynamic conditions under which FI applications must execute call for self-adaptive software to cope with unforeseeable changes in the application environment. Software engineering currently provides frameworks to develop reasoning engines that automatically take reconfiguration decisions and that support the runtime adaptation of distributed, heterogeneous applications. However, these frameworks have very limited support to address security concerns of these application, hindering their usage for FI scenarios. We address this challenge by enhancing self-adaptive systems with the concepts of trust and reputation. Trust will improve decision-making processes under risk and uncertainty, in turn improving security of self-adaptive FI applications. This paper presents an approach that includes a trust and reputation framework into a platform for adaptive, distributed component-based systems, thus providing software components with new abilities to include trust in their reasoning process.

}, isbn = {978-3-642-38323-6}, issn = {1868-4238}, doi = {10.1007/978-3-642-38323-6}, author = {Francisco Moyano and Benoit Baudry and Javier Lopez}, editor = {Carmen Fernandez-Gago and Isaac Agudo and Fabio Martinelli and Siani Pearson} } @proceedings {ifiptm13, title = {Trust Management VII, 7th WG11.11 International conference}, volume = {401}, year = {2013}, month = {June 2013}, publisher = {Springer}, address = {Malaga (Spain)}, isbn = {978-3-642-38323-6}, editor = {Carmen Fernandez-Gago and Fabio Martinelli and Siani Pearson and Isaac Agudo} } @article {1761, title = {Wide-Area Situational Awareness for Critical Infrastructure Protection}, journal = {IEEE Computer}, volume = {46}, number = {4}, year = {2013}, month = {2013}, pages = {30-37}, publisher = {IEEE Computer Society}, abstract = {

Combining a wide-area situational awareness (WASA) methodological framework with a set of requirements for awareness construction can help in the development and commissioning of future WASA cyberdefense solutions

}, issn = {0018-9162}, doi = {10.1109/MC.2013.72}, url = {http://doi.ieeecomputersociety.org/10.1109/MC.2013.72}, author = {Cristina Alcaraz and Javier Lopez} } @inproceedings {1729, title = {Addressing Situational Awareness in Critical Domains of a Smart Grid}, booktitle = {6th International Conference on Network and System Security (NSS 2012)}, series = {LNCS 7645}, volume = {7645}, year = {2012}, month = {November 2012}, pages = {58-71}, publisher = {Springer-Verlag}, organization = {Springer-Verlag}, address = {Wu Yi Shan, Fujian, China}, abstract = {

Control and situational awareness are two very important aspects within critical control systems, since potential faults or anomalous behaviors could lead to serious consequences by hiding the real status of supervised critical infrastructures. Examples of these infrastructures are energy generation, transmission or distribution systems that belong to Smart Grid systems. Given the importance of these systems for social welfare and its economy, a situational awareness-based model, composed of a set of current technologies, is proposed in this paper. The model focuses on addressing and offering a set of minimum services for protection, such as prevention, detection, response, self-evaluation and maintenance, thereby providing a desirable protection in unplanned situations.

}, issn = {978-3-642-34600-2}, doi = {http://dx.doi.org/10.1007/978-3-642-34601-9_5}, author = {Cristina Alcaraz and Javier Lopez} } @inproceedings {Rios2012b, title = {Adecuaci{\'o}n de soluciones de anonimato al problema de la privacidad de localizaci{\'o}n en WSN}, booktitle = {XII Reuni{\'o}n Espa{\~n}ola sobre Criptolog{\'\i}a y Seguridad de la Informaci{\'o}n (RECSI 2012)}, year = {2012}, month = {Sep 2012}, pages = {309-314}, address = {Donostia-San Sebasti{\'a}n}, abstract = {

Los patrones de tr{\'a}fico caracter{\'\i}sticos de las redes inal{\'a}mbricas de sensores (WSNs) dan lugar al problema de la privacidad de localizaci{\'o}n. De manera similar, el tr{\'a}fico de los usuarios en Internet revela informaci{\'o}n sensible que puede ser protegida mediante sistemas de comunicaci{\'o}n an{\'o}nima (ACS). Por ello, este trabajo analiza la posibilidad de adaptar las soluciones de anonimato tradicionales al problema particular de las redes de sensores. Hasta el momento estas soluciones hab{\'\i}an sido rechazadas sin un an{\'a}lisis riguroso, argumentando simplemente que eran demasiado exigentes computacionalmente para los nodos sensores. Nuestros resultados demuestran que, en general, algunos ACS no cumplen los requisitos de privacidad necesarios en WSNs mientras que otros, que si los cumplen, se valen de una cantidad de recursos que superan la capacidad de los sensores.

}, isbn = {978-84-615-9933-2}, author = {Ruben Rios and Javier Lopez}, editor = {U. Zurutuza and R. Uribeetxeberria and I. Arenaza-Nu{\~n}o} } @article {1730, title = {Analysis of Requirements for Critical Control Systems}, journal = {International Journal of Critical Infrastructure Protection (IJCIP)}, volume = {5}, year = {2012}, month = {2012}, pages = {137{\textendash}145}, publisher = {Elsevier}, abstract = {

The use of modern information and communications technologies in supervisory control and data acquisition (SCADA) systems used in the critical infrastructure has become an important topic of research. The modernization significantly enhances operational performance, but also introduces security issues and the associated risks. This paper formally analyzes how the introduction of new technologies can impact control systems and ultimately affect the performance of the critical infrastructure systems being controlled. Five control system requirements are identified with the goal of proposing new operational requirements that trade-off performance and security.

}, issn = {1874-5482}, doi = {10.1016/j.ijcip.2012.08.003}, url = {http://www.sciencedirect.com/science/article/pii/S1874548212000455}, author = {Cristina Alcaraz and Javier Lopez} } @inproceedings {onieva2012, title = {Como proteger la privacidad de los usuarios en Internet. Verificaci{\'o}n an{\'o}nima de la mayor{\'\i}a de edad}, booktitle = {XII Reuni{\'o}n Espa{\~n}ola sobre Criptolog{\'\i}a y Seguridad de la Informaci{\'o}n - RECSI 2012}, year = {2012}, month = {Sep 2012}, pages = {297-302}, publisher = {Mondragon}, organization = {Mondragon}, address = {San Sebastian (Spain)}, isbn = {978-84-615-9933-2}, author = {Jose A. Onieva and Isaac Agudo and Javier Lopez and G. Drapper-Gil and M.F. Hinarejos} } @inproceedings {nunez2012integrating, title = {Integrating OpenID with Proxy Re-Encryption to enhance privacy in cloud-based identity services}, booktitle = {IEEE CloudCom 2012}, year = {2012}, month = {Dec 2012}, pages = {241 - 248}, publisher = {IEEE Computer Society}, organization = {IEEE Computer Society}, address = {Taipei, Taiwan}, abstract = {

The inclusion of identity management in the cloud computing landscape represents a new business opportunity for providing what has been called Identity Management as a Service (IDaaS). Nevertheless, IDaaS introduces the same kind of problems regarding privacy and data confidentiality as other cloud services; on top of that, the nature of the outsourced information (users{\textquoteright} identity) is critical. Traditionally, cloud services (including IDaaS) rely only on SLAs and security policies to protect the data, but these measures have proven insufficient in some cases; recent research has employed advanced cryptographic mechanisms as an additional safeguard. Apart from this, there are several identity management schemes that could be used for realizing IDaaS systems in the cloud; among them, OpenID has gained crescent popularity because of its open and decentralized nature, which makes it a prime candidate for this task. In this paper we demonstrate how a privacy-preserving IDaaS system can be implemented using OpenID Attribute Exchange and a proxy re-encryption scheme. Our prototype enables an identity provider to serve attributes to other parties without being able to read their values. This proposal constitutes a novel contribution to both privacy and identity management fields. Finally, we discuss the performance and economical viability of our proposal.

}, keywords = {Cloud Computing, Cryptography, identity management, OpenID, privacy, proxy re-encryption}, isbn = {978-1-4673-4511-8}, issn = {978-1-4673-4509-5}, doi = {10.1109/CloudCom.2012.6427551}, author = {David Nu{\~n}ez and Isaac Agudo and Javier Lopez} } @incollection {BC2011Alcaraz, title = {Security Aspects of SCADA and DCS Environments}, booktitle = {Critical Infrastructure Protection: Information Infrastructure Models, Analysis, and Defense}, series = {Advances in Critical Infrastructure Protection: Information Infrastructure Models, Analysis, and Defense. LNCS 7130.}, volume = {7130}, year = {2012}, month = {September 2012}, pages = {120-149}, publisher = {Springer-Verlag}, organization = {Springer-Verlag}, address = {Heidelberger (Berlin, Alemania)}, abstract = {

SCADA Systems can be seen as a fundamental component in Critical Infrastructures, having an impact in the overall performance of other Critical Infrastructures interconnected. Currently, these systems include in their network designs different types of Information and Communication Technology systems (such as the Internet and wireless technologies), not only to modernize operational processes but also to ensure automation and real-time control. Nonetheless, the use of these new technologies will bring new security challenges, which will have a significant impact on both the business process and home users. Therefore, the main purpose of this Chapter is to address these issues and to analyze the interdependencies of Process Control Systems with ICT systems, to discuss some security aspects and to offer some possible solutions and recommendations.

}, keywords = {Critical Information Infrastructure Protection, SCADA Systems}, isbn = {ISBN:978-3-642-28919-4}, issn = {0302-9743}, author = {Cristina Alcaraz and Gerardo Fernandez and Fernando Carvajal}, editor = {Javier Lopez and Stephen. Wolthunsen and Roberto Setola} } @article {AlcarazR2012, title = {Selecting key management schemes for WSN applications}, journal = {Computers \& Security}, volume = {31}, number = {38}, year = {2012}, month = {Nov 2012}, pages = {956{\textendash}966}, publisher = {Elsevier}, abstract = {

Key management in wireless sensor networks (WSN) is an active research topic. Due to the fact that a large number of key management schemes (KMS) have been proposed in the literature, it is not easy for a sensor network designer to know exactly which KMS best fits in a particular WSN application. In this article, we offer a comprehensive review on how the application requirements and the properties of various key management schemes influence each other. Based on this review, we show that the KMS plays a critical role in determining the security performance of a WSN network with given application requirements. We also develop a method that allows the network designers to select the most suitable KMS for a specific WSN network setting. In addition, the article also addresses the issues on the current state-of-the-art research on the KMS for homogeneous (i.e. non-hierarchical) networks to provide solutions for establishing link-layer keys in various WSN applications and scenarios.

}, keywords = {security}, issn = {0167-4048}, doi = {10.1016/j.cose.2012.07.002}, url = {http://www.sciencedirect.com/science/article/pii/S0167404812001034}, author = {Cristina Alcaraz and Javier Lopez and Rodrigo Roman and Hsiao-Hwa Chen} } @inproceedings {alcaraz2012b, title = {Smart Grid Privacy: Issues and Solutions}, booktitle = {21st International Conference on Computer Communications and Networks (ICCCN)}, year = {2012}, month = {Jul 2012}, pages = {1-5}, publisher = {IEEE Computer Society}, organization = {IEEE Computer Society}, address = {Munich, Germany}, abstract = {

Migration to an electronically controlled electrical grid to transmit, distribute, and deliver power to consumers has helped enhance the reliability and efficiency of conventional electricity systems. At the same time, this digitally enabled technology called the Smart Grid has brought new challenges to businesses and consumers alike. A key component of such a grid is the smart-metering technology, which is used to collect energy consumption data from homes and transmitting it back to power distributors. A crucial concern is the privacy related to the collection and use of energy consumption data. We present an analysis of Smart Grid privacy issues and discuss recently proposed solutions that can protect the privacy of Smart Grid users.

}, keywords = {Computer architecture, Data privacy, Electricity, Home appliances, privacy, security, Smart grids}, isbn = {978-1-4673-1543-2}, doi = {10.1109/ICCCN.2012.6289304}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=\&arnumber=6289304\&contentType=Conference+Publications\&openedRefinements\%3D*\%26pageNumber\%3D7\%26rowsPerPage\%3D100\%26queryText\%3D\%28smart+grid\%29}, author = {F. Siddiqui and S. Zeadally and Cristina Alcaraz and S. Galvao} } @inproceedings {neumann2012strong, title = {Strong Authentication of Humans and Machines in Policy Controlled Cloud Computing Environment Using Automatic Cyber Identity}, booktitle = {Information Security Solutions Europe 2012}, year = {2012}, month = {2012}, pages = {195-206}, publisher = {Springer Vieweg}, organization = {Springer Vieweg}, address = {Brussels, Belgium}, abstract = {

The paper describes the experience with integration of automatic cyber identity technology with policy controlled virtualisation environment. One identity technology has been used to enable strong authentication of users (human beings) as well as machines (host systems) to the virtualization management system. The real experimental evaluation has been done in PASSIVE project (Policy-Assessed system-level Security of Sensitive Information processing in Virtualised Environments - SEVENTH FRAMEWORK PROGRAMME THEME ICT-2009.1.4 INFORMATION AND COMMUNICATION TECHNOLOGIES - Small or medium-scale focused research project - Grant agreement no.: 257644).

}, isbn = {978-3-658-00332-6}, doi = {10.1007/978-3-658-00333-3_19}, author = {Neumann Libor and Tomas Halman and Rotek Pavel and Alexander Boettcher and Julian Stecklina and Michal Sojka and David Nu{\~n}ez and Isaac Agudo}, editor = {Norbert Pohlmann and Helmut Reimer and Wolfgang Schneider} } @inproceedings {Moyano_ESSoS12, title = {A Task Ordering Approach for Automatic Trust Establishment}, booktitle = {Proceedings of the 2012 International Symposium on Engineering Secure Software and Systems (ESSoS 2012)}, series = {LNCS}, volume = {7159}, year = {2012}, month = {Feb 2012}, pages = {76{\textendash}89}, publisher = {Springer}, organization = {Springer}, address = {Eindhoven, The Netherlands}, abstract = {

Trust has become essential in computer science as a way of assisting the process of decision-making, such as access control. In any system, several tasks may be performed, and each of these tasks might pose different associated trust values between the entities of the system. For instance, in a file system, reading and overwriting a file are two tasks that pose different trust values between the users who can carry out these tasks. In this paper, we propose a simple model for automatically establishing trust relationships between entities considering an established order among tasks.

}, keywords = {task ordering, trust evaluation, trust graph}, doi = {10.1007/978-3-642-28166-2_8}, author = {Francisco Moyano and Carmen Fernandez-Gago and Isaac Agudo and Javier Lopez}, editor = {Gilles Barthe and Ben Livshits and Riccardo Scandariato} } @article {1750, title = {Towards Privacy Protection in Smart Grid}, journal = {Wireless Personal Communications}, volume = {73}, year = {2012}, month = {Nov 2013}, pages = {23-50}, publisher = {Springer}, abstract = {

The smart grid is an electronically controlled electrical grid that connects power generation, transmission, distribution, and consumers using information communication technologies. One of the key characteristics of the smart grid is its support for bi-directional information flow between the consumer of electricity and the utility provider. This two-way interaction allows electricity to be generated in real-time based on consumers{\textquoteright} demands and power requests. As a result, consumer privacy becomes an important concern when collecting energy usage data with the deployment and adoption of smart grid technologies. To protect such sensitive information it is imperative that privacy protection mechanisms be used to protect the privacy of smart grid users. We present an analysis of recently proposed smart grid privacy solutions and identify their strengths and weaknesses in terms of their implementation complexity, efficiency, robustness, and simplicity.

}, keywords = {authentication, Confidentiality, Critical Infrastructure Protection, Energy, privacy, Smart Grid}, isbn = {0929-6212}, issn = {0929-6212}, doi = {10.1007/s11277-012-0939-1}, url = {Wireless Personal Communications}, author = {S. Zeadally and A. Pathan and Cristina Alcaraz and M. Badra} } @inproceedings {Najera_JITEL11, title = {Acceso seguro a nodos RFID en una arquitectura de red personal}, booktitle = {X Jornadas de Ingenier{\'\i}a Telem{\'a}tica (JITEL 2011)}, year = {2011}, month = {09/2011}, pages = {104 - 111}, publisher = {Universidad de Cantabria}, organization = {Universidad de Cantabria}, address = {Santander, Spain}, abstract = {

El paradigma de red personal (PN) permitir\á la interacci\ón y colaboraci\ón del creciente abanico de dispositivos personales. Con tal fin la PN ha de integrar en su seno m\últiples tecnolog\ías heterog\éneas con diversas capacidades computacionales y de comunicaci\ón de forma segura. En particular, la incorporaci\ón de la tecnolog\ía RFID en objetos personales conlleva m\últiples riesgos de seguridad y privacidad que han suscitado un elevado inter\és de la comunidad investigadora en los \últimos a\ños. M\ás all\á de su seguridad de forma aislada, su integraci\ón en la PN y la interacci\ón de \ésta con redes de \área extensa como Internet of Things requieren una arquitectura de red personal adecuada para tal contexto. Este art\ículo proporciona los fundamentos de tal arquitectura segura incluyendo el an\álisis de aspectos como la incorporaci\ón e inicializaci\ón de las restringidas etiquetas RFID en la red personal, la autenticaci\ón tanto de miembros de la PN como de usuarios y servicios remotos en su acceso a las tecnolog\ías de contexto, el control de las pol\íticas de privacidad y el establecimiento de canales seguros de comunicaci\ón supervisados.

}, keywords = {arquitectura software, red personal, Seguridad RFID}, isbn = {978-84-694-5948-5}, author = {Pablo Najera and Rodrigo Roman and Javier Lopez}, editor = {Klaus Hackbarth and Ram{\'o}n Ag{\"u}ero and Roberto Sanz} } @inproceedings {agudo2011cryptography, title = {Cryptography Goes to the Cloud}, booktitle = {1st International Workshop on Security and Trust for Applications in Virtualised Environments (STAVE 2011)}, series = {Communications in Computer and Information Science}, volume = {187}, year = {2011}, month = {June}, pages = {190-197}, publisher = {Springer}, organization = {Springer}, abstract = {

In this paper we identify some areas where cryptography can help a rapid adoption of cloud computing. Although secure storage has already captured the attention of many cloud providers, offering a higher level of protection for their customer{\textquoteright}s data, we think that more advanced techniques such as searchable encryption and secure outsourced computation will become popular in the near future, opening the doors of the Cloud to customers with higher security requirements.

}, isbn = {978-3-642-22364-8}, doi = {10.1007/978-3-642-22365-5_23}, author = {Isaac Agudo and David Nu{\~n}ez and Gabriele Giammatteo and Panagiotis Rizomiliotis and Costas Lambrinoudakis}, editor = {Changhoon Lee and Jean-Marc Seigneur and James J. Park and Roland R. Wagner} } @incollection {Alcaraz2011_ChapterBook, title = {Digital Home Networking: Standards}, booktitle = {Digital Home Networking}, number = {7130}, year = {2011}, pages = {60-96}, publisher = {John Wiley \& Sons Inc.}, organization = {John Wiley \& Sons Inc.}, address = {Reino Unido}, keywords = {Standards, ZigBee}, issn = {978-1-84821-321-0}, author = {Remi Bars and Jorge Gomez and Mohamed Mahdi and Cristina Alcaraz and Rodrigo Roman}, editor = {Romain Carbou and Ernesto Exposito and Rodrigo Roman and Michel Diaz} } @article {Alcaraz2011, title = {An Early Warning System based on Reputation for Energy Control Systems}, journal = {IEEE Transactions on Smart Grid}, volume = {2}, number = {4}, year = {2011}, month = {Nov 2011}, pages = {827-834}, publisher = {IEEE}, abstract = {

Most of energy control or SCADA (Supervisory Control and Data Acquisition) systems are very dependent on advanced technologies and on traditional security mechanisms for protecting the a system against anomalous events. Security mechanisms are not enough to be used in critical systems, since they can only detect anomalous events occurring at a certain moment in time. For this reason it becomes of paramount importance the usage of intelligent systems with capability for preventing anomalous situations and reacting against them on time. This type of systems are, for example, Early Warning Systems (EWS). In this paper, we propose an EWS based on Wireless Sensor Networks (WSNs) (under the ISA100.11a standard) and reputation for controling the network behaviour. The WSN are organized into clusters where a Cluster Head (CH) is designated. This CH will contain a Reputation Manager Module. The usability of this approach is also analyzed considering a Smart Grid scenario.} keywords = {Critical Information Infrastructures, Sensor Networks, Early Warning Systems, Reputation, SCADA Systems, Smart Grid.

}, keywords = {Early Warning Systems, Reputation, SCADA Systems, Smart Grid, wireless sensor networks}, issn = {1949-3053}, doi = {10.1109/TSG.2011.2161498}, author = {Cristina Alcaraz and Carmen Fernandez-Gago and Javier Lopez} } @inproceedings {DNunez11, title = {Identity Management Challenges for Intercloud Applications}, booktitle = {1st International Workshop on Security and Trust for Applications in Virtualised Environments (STAVE 2011)}, volume = {187}, year = {2011}, month = {June}, pages = {198-204}, address = {Crete (Greece)}, abstract = {

Intercloud notion is gaining a lot of attention lately from both enterprise and academia, not only because of its benefits and expected results but also due to the challenges that it introduces regarding interoperability and standardisation. Identity management services are one of the main candidates to be outsourced into the Intercloud, since they are one of the most common services needed by companies and organisations. This paper addresses emerging identity management challenges that arise in intercloud formations, such as naming, identification, interoperability, identity life cycle management and single sign-on.

}, doi = {10.1007/978-3-642-22365-5_24}, author = {David Nu{\~n}ez and Isaac Agudo and Prokopios Drogkaris and Stefanos Gritzalis} } @article {roman2011, title = {Key management systems for sensor networks in the context of the Internet of Things}, journal = {Computers \& Electrical Engineering}, volume = {37}, year = {2011}, month = {Mar 2011}, pages = {147-159}, publisher = {Elsevier}, abstract = {

If a wireless sensor network (WSN) is to be completely integrated into the Internet as part of the Internet of Things (IoT), it is necessary to consider various security challenges, such as the creation of a secure channel between an Internet host and a sensor node. In order to create such a channel, it is necessary to provide key management mechanisms that allow two remote devices to negotiate certain security credentials (e.g. secret keys) that will be used to protect the information flow. In this paper we will analyse not only the applicability of existing mechanisms such as public key cryptography and pre-shared keys for sensor nodes in the IoT context, but also the applicability of those link-layer oriented key management systems (KMS) whose original purpose is to provide shared keys for sensor nodes belonging to the same WSN.

}, issn = {0045-7906}, doi = {10.1016/j.compeleceng.2011.01.009}, url = {http://www.sciencedirect.com/science/article/B6V25-527FRSD-1/2/62661c595153993639c43b9b331d8d66}, author = {Rodrigo Roman and Cristina Alcaraz and Javier Lopez and Nicolas Sklavos} } @inproceedings {1643, title = {Managing Incidents in Smart Grids {\`a} la Cloud}, booktitle = {IEEE CloudCom 2011}, year = {2011}, month = {Nov-Dec 2011}, pages = {527-531}, publisher = {IEEE Computer Society}, organization = {IEEE Computer Society}, address = {Athens, Greece}, abstract = {

During the last decade, the Cloud Computing paradigm has emerged as a panacea for many problems in traditional IT infrastructures. Much has been said about the potential of Cloud Computing in the Smart Grid context, but unfortunately it is still relegated to a second layer when it comes to critical systems. Although the advantages of outsourcing those kind of applications to the cloud is clear, data confidentiality and operational privacy stand as mayor drawbacks. In this paper, we try to give some hints on which security mechanisms and more specific, which cryptographic schemes, will help a better integration of Smart Grids and Clouds. We propose the use of Virtual SCADA in the Cloud (VS-Cloud) as a mean to improve reliability and efficiency whilst maintaining the same protection level as in traditional SCADA architectures.

}, keywords = {Cloud Computing, Cryptography, Incident Management, SCADA Systems, Searchable Encryption, Smart Grid}, isbn = {978-0-7695-4622-3}, doi = {10.1109/CloudCom.2011.79}, author = {Cristina Alcaraz and Isaac Agudo and David Nu{\~n}ez and Javier Lopez} } @article {vivas2010, title = {A methodology for security assurance-driven system development}, journal = {Requirements Engineering}, volume = {16}, number = {1}, year = {2011}, month = {Mar 2011}, pages = {55-73}, publisher = {Springer}, abstract = {

In this work, we introduce an assurance methodology that integrates assurance case creation with system development. It has been developed in order to provide trust and privacy assurance to the evolving European project PICOS (Privacy and Identity Management for Community Services), an international research project focused on mobile communities and community-supporting services, with special emphasis on aspects such as privacy, trust, and identity management. The leading force behind the approach is the ambition to develop a methodology for building and maintaining security cases throughout the system development life cycle in a typical system engineering effort, when much of the information relevant for assurance is produced and feedback can be provided to system developers. The first results of the application of the methodology to the development of the PICOS platform are presented.

}, issn = {0947-3602}, doi = {10.1007/s00766-010-0114-8}, author = {Jose L. Vivas and Isaac Agudo and Javier Lopez} } @inproceedings {6059235, title = {OSAMI Commons: An open dynamic services platform for ambient intelligence}, booktitle = {IEEE 16th Conference on Emerging Technologies Factory Automation (ETFA 2011)}, year = {2011}, month = {Sep 2011}, pages = {1-10}, publisher = {IEEE}, organization = {IEEE}, address = {Toulouse, France}, abstract = {

Today we live in an environment surrounded with networked converging devices. Human computer interactions are becoming personalized and a new concept of a global and cross-domain platform is emerging to exploit the full potential of the network in all business areas. In this convergence process, the software platform should be able to personalize itself dynamically in devices according to the context. OSAmI-Commons, an ITEA2 project for developing an open-source common approach to such a dynamic service-based platform, allows any type of device to connect and exchange information and services. OSAMI consortium is contributing to defining the foundations of a cross-platform open-services ecosystem. The sustainability of this platform is an objective beyond the project duration.

}, isbn = {978-1-4577-0016-3}, issn = {1946-0740}, doi = {10.1109/ETFA.2011.6059235}, author = {Naci Dai and Jesus Bermejo and Felix Cuadrado Latasa and Alejandra Ruiz L{\'o}pez and Isaac Agudo and Elmar Zeeb and Jan Krueger and Oliver Dohndorf and Wolfgang Thronicke and Christoph Fiehe and Anna Litvina} } @article {Alcaraz2011a, title = {Secure SCADA Framework for the Protection of Energy Control Systems}, journal = {Concurrency and Computation Practice \& Experience}, volume = {23}, number = {12}, year = {2011}, month = {Aug 2011}, pages = {1414-1430}, publisher = {John Wiley \& Sons, Inc.}, abstract = {

Energy distribution systems are becoming increasingly widespread in today{\textquoteright}s society.\ One of the elements that is used to monitor and control these systems are the SCADA\ (Supervisory Control and Data Acquisition) systems. In particular, these control systems\ and their complexities, together with the emerging use of the Internet and wireless\ technologies, bring new challenges that must be carefully considered. Examples of such\ challenges are the particular bene{\textasciimacron}ts of the integration of those new technologies, and\ also the e{\textregistered}ects they may have on the overall SCADA security. The main task of this\ paper is to provide a framework that shows how the integration of di{\textregistered}erent state-of-the-art technologies in an energy control system, such as Wireless Sensor Networks (WSNs),\ Mobile Ad-Hoc Networks (MANETs), and the Internet, can bring some interesting\ benefits such as status management and anomaly prevention, while maintaining the\ security of the whole system.

}, keywords = {Energy Distribution and Control Systems, SCADA Systems, Sensor Networks}, isbn = {23(12)1311-1464 (2011)}, issn = {1532-0626}, doi = {10.1002/cpe.1679}, author = {Cristina Alcaraz and Javier Lopez and Jianying Zhou and Rodrigo Roman} } @inproceedings {Roman11SK, title = {SenseKey - Simplifying the Selection of Key Management Schemes for Sensor Networks}, booktitle = {5th International Symposium on Security and Multimodality in Pervasive Environments (SMPE{\textquoteright}11)}, year = {2011}, month = {March}, publisher = {IEEE}, organization = {IEEE}, address = {Singapore}, abstract = {

Key Management Schemes (KMS) are a very important security mechanism for Wireless Sensor Networks (WSN), as they are used to manage the credentials (i.e. secret keys) that are needed by the security primitives. There is a large number of available KMS protocols in the literature, but it is not clear what should network designers do to choose the most suitable protocol for the needs of their applications. In this paper, we consider that given a certain set of application requirements, the network designer can check which properties comply with those requirements and select the KMS protocols that contains those particular properties. Therefore, we study the relationship between requirements and properties, and we provide a web tool, the SenseKey tool, that can be used to automatically obtain an optimal set of KMS protocols.

}, doi = {10.1109/WAINA.2011.78}, url = {http://www.ftrai.org/smpe2011/}, author = {Rodrigo Roman and Javier Lopez and Cristina Alcaraz and Hsiao Hwa Chen} } @inproceedings {Alcaraz2010, title = {Acceso seguro a redes de sensores en SCADA a trav{\'e}s de Internet}, booktitle = {XI Reuni{\'o}n Espa{\~n}ola sobre Criptolog{\'\i}a y Seguridad de la Informaci{\'o}n (RECSI 2010)}, year = {2010}, month = {September}, pages = {337-342}, address = {Tarragona (Spain)}, abstract = {

Las Infraestructuras Cr\íticas (ICs) son monitorizadas por sistemas altamente complejos, conocidos como sistemas SCADA (Sistemas de Control y Adquisici\ón de Datos), cuyo principal soporte se encuentra en las subestaciones, las cuales miden de primera instancia el estado real de tales ICs. Para mejorar este control, la industria est\á actualmente demandando la integraci\ón en el modelo tradicional de dos avances tecnol\ógicos: Internet y las redes de sensores inal\ámbricas. Sin embargo, su incorporaci\ón requiere analizar los requisitos de seguridad que surgen en dicho contexto, as\í como diversos aspectos correlacionados (ej. mantenimiento, rendimiento, seguridad y optimizaci\ón) y, en base a estos, la estrategia de integraci\ón m\ás adecuada para satisfacer dichos requisitos. Este art\ículo proporciona dicho an\álisis en profundidad con el fin de ofrecer un modelo de integraci\ón seguro adecuado para entornos cr\íticos.

}, keywords = {el Internet, Internet of Things, Redes Mesh Inal{\'a}mbrica de Sensores, Sistemas Cr{\'\i}ticos de Control, Sistemas SCADA}, isbn = {978-84-693-3304-4}, url = {http://crises-deim.urv.cat/recsi2010/}, author = {Cristina Alcaraz and Rodrigo Roman and Pablo Najera and Javier Lopez} } @article {1589, title = {Digital Identity and Identity Management Technologies}, journal = {UPGRADE - The European Journal of the Informatics Professional}, volume = {2010}, year = {2010}, pages = {6 - 12}, publisher = {CEPIS}, abstract = {

There are many technologies for identity management available in the form of open specifications, open source tools and commercial applications. Currently, there are some competing standards for identity management. At the beginning SAML was the only viable choice with a higher enough acceptance level. Recently, another technology called WS-Federation has also gain some attention from the community. Although this technology is not as mature as SAML, it modular design gives it some advantages over SAML. It this work we mainly focus on the WS-Federation and the family of specifications that surround it.

}, issn = {1684-5285}, url = {http://www.cepis.org/upgrade/files/issue-1-2010-agudo.ruiz.pdf}, author = {Isaac Agudo} } @inproceedings {Agudo2010, title = {Distribuci{\'o}n segura de componentes software basada en OpenID}, booktitle = {XI Reuni{\'o}n Espa{\~n}ola sobre Criptolog{\'\i}a y Seguridad de la Informaci{\'o}n (RECSI 2010)}, year = {2010}, month = {September}, address = {Tarragona, Spain}, abstract = {

En la actualidad, cada vez son m\ás frecuentes los ataques software mediante la utilizaci\ón de malware o sustituci\ón de programas (o componentes) en los repositorios a los cuales los usuarios finales (o m\áquinas) acceden. Esta situaci\ón se ve de alguna manera acentuada con el dinamismo existente en la programaci\ón y ejecuci\ón de estos componentes, en la que distintos desarrolladores pueden participar para desplegar un determinado servicio o parte de \él. Por ello, en este art\ículo se presenta una soluci\ón para la distribuci\ón de c\ódigo de forma segura usando OpenID y firmas con certificados de clave p\ública de corta duraci\ón. De esta forma, se consigue un compromiso de seguridad que permite distribuir c\ódigo firmado sin la necesidad de que los desarrolladores dispongan a priori de un certificado espec\ífico. Presentamos adem\ás algunos detalles acerca de la implementaci\ón realizada para hacer realidad este dise\ño.

}, isbn = {978-84-693-3304-4}, author = {Isaac Agudo and Jose A. Onieva and Daniel Merida} } @inproceedings {Alcaraz2010b, title = {Early Warning System for Cascading Effect Control in Energy Control Systems}, booktitle = {5th International conference on Critical Information Infrastructures Security (CRITIS{\textquoteright}10)}, series = {LNCS}, volume = {6712}, year = {2010}, month = {September}, pages = {55-67}, publisher = {Springer}, organization = {Springer}, address = {Athens, Greece}, abstract = {

A way of controlling a cascading effect caused by a failure or a threat in a critical system is using intelligent mechanisms capable of predicting anomalous behaviours and also capable of reacting against them in advance. These mechanisms are known as Early Warning Systems (EWS) and this will be precisely the main topic of this paper. Specially, we present an EWS design based on a Wireless Sensor Network (using the ISA100.11a standard) that constantly supervise the application context. This EWS is also based on forensic techniques to provide dynamic learning capacities. As a result, this new approach will aid to provide a reliable control of incidences by offering a dynamic alarm management, identification of the most suitable field operator to attend an alarm, reporting of causes and responsible operators, and learning from new anomalous situations.

}, keywords = {Cascading Effect, Early Warning System, Energy Control Systems, Forensic Techniques, SCADA Systems, Wireless Sensor Network}, isbn = {978-3-642-21693-0}, issn = {0302-9743}, url = {http://critis.net/2010/}, author = {Cristina Alcaraz and Angel Balastegui and Javier Lopez} } @inproceedings {Rios2010a, title = {Implementaci{\'o}n de un esquema de localizaci{\'o}n privada y segura para interiores}, booktitle = {IX Jornadas de Ingenier{\'\i}a Telem{\'a}tica (JITEL{\textquoteright}10)}, year = {2010}, month = {Sept.}, pages = {237 - 244}, address = {Valladolid (Spain)}, abstract = {

Las aplicaciones basadas en localizaci\ón proporcionan a los usuarios servicios personalizados dependiendo de su ubicaci\ón. Las estimaciones prev\én que estos servicios se extender\án enormemente en los pr\óximos a\ños reportando grandes beneficios tanto a la industria como a los usuarios finales. Sin embargo, para que estos avances sean posibles se hace necesario analizar en profundidad las distintas implicaciones de seguridad y privacidad que la utilizaci\ón de tales servicios pueden traer consigo a los usuarios. En este trabajo proponemos un sistema de localizaci\ón que da soporte a la provisi\ón de servicios basados en localizaci\ón para entornos indoor y que se fundamenta en la tecnolog\ía de redes de sensores inal\ámbricos. En este esquema hemos tenido en cuenta diversos aspectos de seguridad y privacidad, prestando especial atenci\ón a la limitaci\ón extrema de recursos caracter\ística de las redes de sensores. Finalmente hemos desarrollado una prueba de concepto para comprobar la viabilidad de nuestro esquema dentro del \ámbito del proyecto OSAmI.

}, isbn = {978-84-693-5398-1}, author = {Ruben Rios and Isaac Agudo and Jose L. Gonzalez}, editor = {Yannis Dimitriadis and Mar{\'\i}a Jes{\'u}s Verd{\'u} P{\'e}rez} } @article {JordiForne2009, title = {Pervasive Authentication and Authorization Infrastructures for Mobile Users}, journal = {Computer and Security}, volume = {29}, year = {2010}, pages = {501-514}, publisher = {elsevier}, abstract = {

Network and device heterogeneity, nomadic mobility, intermittent connectivity and, more generally, extremely dynamic operating conditions, are major challenges in the design of security infrastructures for pervasive computing. Yet, in a ubiquitous computing environment, limitations of traditional solutions for authentication and authorization can be overcome with a pervasive public key infrastructure (pervasive-PKI). This choice allows the validation of credentials of users roaming between heterogeneous networks, even when global connectivity is lost and some services are temporarily unreachable. Proof-of-concept implementations and testbed validation results demonstrate that strong security can be achieved for users and applications through the combination of traditional PKI services with a number of enhancements like: (i) dynamic and collaborative trust model, (ii) use of attribute certificates for privilege management, and (iii) modular architecture enabling nomadic mobility and enhanced with reconfiguration capabilities.

}, issn = {0167-4048}, doi = {10.1016/j.cose.2009.09.001}, author = {Jordi Forne and Francisca Hinajeros and Andres Marin and Florina Almenarez and Javier Lopez and Jose A. Montenegro and Marc Lacoste and Daniel Diaz} } @article {Agudo2010b, title = {A Scale Based Trust Model for Multi-Context Environments}, journal = {Computers and Mathematics with Applications}, volume = {60}, year = {2010}, month = {July}, pages = {209-216}, publisher = {Elsevier}, abstract = {

When interactions among users of a system have to take place, for example, over the internet, establishing trust relationships among these users becomes crucial. However, the way this trust is established depends to a certain extent on the context where the interactions take place. Most of the time, trust is encoded as a numerical value that might not be very meaningful for a not very experienced user. In this paper we propose a model that takes into account the semantic and the computational sides of trust. This avoids users having to deal directly with the computational side; they instead deal with meaningful labels such as Bad or Good in a given context.

}, issn = {0898-1221}, doi = {10.1016/j.camwa.2010.02.009}, author = {Isaac Agudo and Carmen Fernandez-Gago and Javier Lopez} } @article {Alcaraz2010a, title = {A Security Analysis for Wireless Sensor Mesh Networks in Highly Critical Systems}, journal = {IEEE Transactions on Systems, Man, and Cybernetics, Part C: Applications and Reviews}, volume = {40}, number = {4}, year = {2010}, month = {July}, pages = {419-428}, publisher = {IEEE}, abstract = {

Nowadays, critical control systems are a fundamental component contributing to the overall performance of critical infrastructures in our society, most of which belong to the industrial sector. These complex systems include in their design different types of information and communication technology systems, such as wireless (mesh) sensor networks, to carry out control processes in real time. This fact has meant that several communication standards, such as Zigbee PRO, WirelessHART, and ISA100.11a, have been specified to ensure coexistence, reliability, and security in their communications. The main purpose of this paper has been to review these three standards and analyze their security. We have identified a set of threats and potential attacks in their routing protocols, and we consequently provide recommendations and countermeasures to help Industry protect its infrastructures.

}, keywords = {Critical Control Systems, Critical Infrastructure Protection, SCADA Systems, Wireless Sensor Mesh Network}, issn = {1094-6977}, doi = {10.1109/TSMCC.2010.2045373}, url = {http://ieeexplore.ieee.org/search/srchabstract.jsp?tp=\&arnumber=5443456\&queryText\%253DC.+Alcaraz\%2526openedRefinements\%253D*\%2526searchField\%253DSearch+All\&fromGateway=true}, author = {Cristina Alcaraz and Javier Lopez} } @article {JavierLopezMunoz2010, title = {Trust Management Systems for Wireless Sensor Networks: Best practices}, journal = {Computer Communications}, volume = {33}, number = {9}, year = {2010}, pages = {0140-3664}, publisher = {Elsevier}, abstract = {

Wireless sensor networks (WSNs) have been proven a useful technology for perceiving information about the physical world and as a consequence has been used in many applications such as measurement of temperature, radiation, flow of liquids, etc. The nature of this kind of technology, and also their vulnerabilities to attacks make the security tools required for them to be considered in a special way. The decision making in a WSN is essential for carrying out certain tasks as it aids sensors establish collaborations. In order to assist this process, trust management systems could play a relevant role. In this paper, we list the best practices that we consider are essential for developing a good trust management system for WSN and make an analysis of the state of the art related to these practices.

}, issn = {0140-3664}, doi = {10.1016/j.comcom.2010.02.006}, author = {Javier Lopez and Rodrigo Roman and Isaac Agudo and Carmen Fernandez-Gago} } @inproceedings {calcaraz10, title = {Wireless Sensor Networks and the Internet of Things: Do We Need a Complete Integration?}, booktitle = {1st International Workshop on the Security of the Internet of Things (SecIoT{\textquoteright}10)}, year = {2010}, month = {December}, pages = {xxxx}, publisher = {IEEE}, organization = {IEEE}, address = {Tokyo (Japan)}, abstract = {

Wireless sensor networks (WSN) behave as a digital skin, providing a virtual layer where the information about the physical world can be accessed by any computational system. As a result, they are an invaluable resource for realizing the vision of the Internet of Things (IoT). However, it is necessary to consider whether the devices of a WSN should be completely integrated into the Internet or not. In this paper, we tackle this question from the perspective of security. While we will mention the different security challenges that may arise in such integration process, we will focus on the issues that take place at the network level.

}, issn = {xxxx}, author = {Cristina Alcaraz and Pablo Najera and Javier Lopez and Rodrigo Roman} } @inproceedings {Alcaraz2009, title = {Adaptive Dispatching of Incidences Based on Reputation for SCADA Systems}, booktitle = {6th International Conference on Trust, Privacy and Security in Digital Business (TrustBus{\textquoteright}09)}, series = {LNCS}, year = {2009}, month = {September}, pages = {86-94}, publisher = {Springer-Verlag}, organization = {Springer-Verlag}, address = {Linz, Austria}, abstract = {

SCADA systems represent a challenging scenario where the management of critical alarms is crucial. Their response to these alarms should be efficient and fast in order to mitigate or contain undesired effects. This work presents a mechanism, the Adaptive Assignment Manager (AAM) that will aid to react to incidences in a more efficient way by dynamically assigning alarms to the most suitable human operator. The mechanism uses various inputs for identifying the operators such as their availability, workload and reputation. In fact, we also define a reputation component that stores the reputation of the human operators and uses feedback from past experiences.

}, keywords = {Critical Control Systems, Reputation, Supervisory Control and Data Acquisition Systems}, isbn = {978-3-642-03747-4}, doi = {10.1007/978-3-642-03748-1_9}, author = {Cristina Alcaraz and Isaac Agudo and Carmen Fernandez-Gago and Rodrigo Roman and Gerardo Fernandez and Javier Lopez} } @inproceedings {Lopez2009, title = {Analysis of Security Threats, Requirements, Technologies and Standards in Wireless Sensor Networks}, booktitle = {Foundations of Security Analysis and Design 2009}, series = {LNCS}, volume = {5705}, year = {2009}, month = {August}, pages = {289-338}, publisher = {Springer Berlin/Heidelberg}, organization = {Springer Berlin/Heidelberg}, address = {Bertinoro (Italy)}, abstract = {

As sensor networks are more and more being implemented in real world settings, it is necessary to analyze how the different requirements of these real-world applications can influence the security mechanisms. This paper offers both an overview and an analysis of the relationship between the different security threats, requirements, applications, and security technologies. Besides, it also overviews some of the existing sensor network standards, analyzing their security mechanisms.

}, isbn = {978-3-642-03828-0}, issn = {0302-9743 (Print) 1611-3349 (Online)}, doi = {10.1007/978-3-642-03829-7_10}, url = {http://www.springerlink.com/content/u8h4882831k474n6/}, author = {Javier Lopez and Rodrigo Roman and Cristina Alcaraz} } @article {Agudo2009, title = {Concurrent access control for multi-user and multi-processor systems based on trust relationships}, journal = {Concurrency and Computation: Practice and Experience}, volume = {21}, year = {2009}, month = {July}, pages = {1389-1403}, publisher = {John Wiley \& Sons}, abstract = {

Concurrent access control is an old problem in many fields in Computer Science. It has been solved in many languages and systems, using mechanisms like monitors or priority queues. Nowadays computers implement multi-core capabilities. This means that they are virtually capable of execution of processes in parallel. This requires new techniques and open new issues in the field of concurrent access control. Moreover, most operating systems are multi-user; thus, we have to focus on a multi-processor multi-user scenario. Trust becomes a paramount aspect when building distributed applications; the same applies on a lower scale in modern computers. We propose the use of a trust graph that keeps record of the trust relationships of the system and helps in deciding on concurrent access requests. The information encoded in the graph will be used both in order to decide on the access requests and to order granted requests in terms of their associated trust level

}, issn = {1532-0626}, doi = {10.1002/cpe.1430}, author = {Isaac Agudo and Carmen Fernandez-Gago and Javier Lopez} } @inproceedings {roman2009, title = {Do Wireless Sensor Networks Need to be Completely Integrated into the Internet?}, booktitle = {3rd CompanionAble Workshop - Future Internet of People, Things and Services (IoPTS) eco-Systems}, year = {2009}, month = {December}, pages = {xxxx}, publisher = {xxxx}, organization = {xxxx}, address = {Brussels (Belgium)}, abstract = {

Wireless sensor networks are considered as an integral part of the Internet of Things paradigm. Not only they provide a virtual presence to elements of the real world, but also allow any computationalsystem to know about the physical state of those elements thanks to the use of embedded sensors. In order to belong to the Internet of Things, the elements of a sensor network can implement Internet protocols and services such as the TCP/IP stack and web services. Still, a question that must be raised at this point of time is whether all sensor network applications should be completely integrated into the Internet or not. The purpose of this paper is to analyze this question, reviewing the challenges and security requirements of Internet-enabled sensor networks.

}, issn = {xxxx}, author = {Rodrigo Roman and Javier Lopez and Cristina Alcaraz} } @inproceedings {Agudo2009a, title = {A Multidimensional Reputation Scheme for Identity Federations}, booktitle = {Sixth European Workshop on Public Key Services, Applications and Infrastructures (EuroPKI{\textquoteright}09)}, series = {LNCS}, volume = {6391}, year = {2009}, pages = {225-238}, publisher = {Springer}, organization = {Springer}, abstract = {

Deciding who to trust in the internet of services paradigm is an important and open question. How to do it in an optimal way is not always easy to determine. Trust is usually referred to a particular context whereas a single user may interact in more than one given context. We are interested in investigating how a Federated Reputation System can help exporting trust perceptions from one context to another. We propose a model for deriving trust in online services. In this context, trust is defined as the level of confidence that the service provider holds on the subject interacting with it to behave in a proper way while using the service. Thus, we derive trust by using the reputation values that those users have gained for interacting with these services.

}, isbn = {978-3-642-16440-8}, issn = {0302-9743 (Print) 1611-3349 (Online)}, doi = {10.1007/978-3-642-16441-5_15}, author = {Isaac Agudo and Carmen Fernandez-Gago and Javier Lopez} } @inproceedings {vivas09, title = {Security Assurance During the Software Development Process}, booktitle = {International Conference on Computer Systems and Technologies (CompSysTech09)}, year = {2009}, pages = {11.7.1-11.7.6}, publisher = {ACM}, organization = {ACM}, address = {Ruse (Bulgary)}, abstract = {

Assurance has been a major topic for critical systems. Assurance is usually associated with safety conditions but has also an important role for checking security requirements. Security is best assured if it is addressed holistically, systematically, and from the very beginning in the software{\textquoteright}s development process. We propose to integrate assurance and system development by letting the different stages of the system development life-cycle be mapped to the structure of the assurance case.

}, isbn = {978-1-60558-986-2}, doi = {10.1145/1731740.1731763}, author = {Jose L. Vivas and Isaac Agudo and Javier Lopez} } @inproceedings {Alcaraz2008, title = {An{\'a}lisis de la Aplicabilidad de las Redes de Sensores para la Protecci{\'o}n de Infraestructuras de Informaci{\'o}n Cr{\'\i}ticas}, booktitle = {VI Jornadas de Ingenier{\'\i}a Telem{\'a}tica (JITEL{\textquoteright}08)}, year = {2008}, month = {September}, pages = {437}, address = {Alcal{\'a} de Henares (Spain)}, abstract = {

Las infraestructuras cr\íticas, como el sector energ\ético, la banca, el transporte, y muchas otras, son un pilar esencial para en bienestar de la sociedad y la econom\ía de un pa\ís. Estas infraestructuras dependen a su vez de ciertas infraestructuras de informaci\ón, las cuales permiten su correcto funcionamiento. La tarea de proteger esas infraestructuras (de informaci\ón) cr\íticas es compleja y multidimensional, con una gran cantidad de desaf\íos por resolver. Precisamente, las redes de sensores pueden ser de gran ayuda para esta tarea, debido a suscapacidades de control distribuidas y a su habilidad de funcionar en situaciones extremas. Este art\ículo analiza la utilidad de las redes de sensores en este contexto, describiendo tanto sus capacidades como sus posibles roles y mecanismos de integraci\ón para la protecci\ón de infraestructuras (de informaci\ón) cr\íticas.

}, isbn = {978-84-612-5474-3}, url = {http://www.telematica.ws/jitel/2008/default.htm}, author = {Cristina Alcaraz and Rodrigo Roman and Javier Lopez} } @inproceedings {Agudo2008, title = {Delegating Privileges over Finite Resources: A Quota Based Delegation Approach}, booktitle = {5th International Workshop on Formal Aspects in Security and Trust (FAST{\textquoteright}08)}, series = {LNCS}, volume = {5491}, year = {2008}, pages = {302-315}, publisher = {Springer}, organization = {Springer}, address = {Malaga (Spain)}, abstract = {

When delegation in real world scenarios is considered, the delegator (the entity that posses the privileges) usually passes the privileges on to the delegatee (the entity that receives the privileges) in such a way that the former looses these privileges while the delegation is effective. If we think of a physical key that opens a door, the privilege being delegated by the owner of the key is opening the door. Once the owner of the key delegates this privilege to another entity, by handing over the key, he is not able to open the door any longer. This is due to the fact that the key is not copied and handed over but handed over to the delegatee. When delegation takes place in the electronic world, the delegator usually retains also the privileges. Thus, both users have them simultaneously. This situation, which in most cases is not a problem, may be undesirable when dealing with certain kind of resources. In particular, if we think of finite resources, those in which the number of users accessing simultaneously is finite, we can not allow that a user delegating his access privilege is also granted access when the delegation if effective. In this paper we propose an approach where each user is delegated an access quota for a resource. If further delegating of the delegated quota occurs, this is subtracted from his quota. That is, when delegating, part of the quota remains with the delegator and another part goes to the delegatee. This allows a more fairly access to the resource. Moreover, we show that this approach can also be applied to any kind of resources by defining appropriate authorization policies.

}, isbn = {978-3-642-01464-2}, issn = {0302-9743 (Print) 1611-3349 (Online)}, doi = {10.1007/978-3-642-01465-9}, author = {Isaac Agudo and Carmen Fernandez-Gago and Javier Lopez} } @article {Agudo2008d, title = {Enabling Attribute Delegation in Ubiquitous Environments}, journal = {Mobile Networks and Applications}, volume = {13}, number = {3-4}, year = {2008}, month = {August}, pages = {398-410}, publisher = {Springer}, abstract = {

When delegation is implemented using the attribute certificates in a Privilege Management Infrastructure (PMI), it is possible to reach a considerable level of distributed functionality. However, the approach is not flexible enough for the requirements of ubiquitous environments. The PMI can become a too complex solution for devices such as smartphones and PDAs, where resources are limited. In this work we present an approach to solve the previous limitations by defining a second class of attributes, called domain attributes, which are managed directly by users and are not right under the scope of the PMI, thus providing a light solution for constrained devices. However, we relate the two classes of attributes are related by defining a simple ontology. While domain attribute credentials are defined using SAML notation, global attributes are defined using X.509 certificates. For this reason, we additionally introduce XSAML so that both kinds of credentials are integrated. We also introduce the concept of Attribute Federation which is responsible for supporting domain attributes and the corresponding ontology.

}, keywords = {attribute based authorization, delegation, federation}, issn = {1383-469X}, doi = {10.1007/s11036-008-0062-4}, author = {Isaac Agudo and Javier Lopez and Jose A. Montenegro} } @inproceedings {Agudo2008b, title = {An Evolutionary Trust and Distrust Model}, booktitle = {4th Workshop on Security and Trust Management (STM{\textquoteright}08)}, series = {ENTCS}, volume = {224}, year = {2008}, pages = {3-12}, publisher = {Elsevier}, organization = {Elsevier}, address = {Trondheim, Norway}, abstract = {

In this paper we propose a trust model, where besides considering trust and distrust, we also consider another parameter that measures the reliability on the stability of trust or distrust. The inclusion of this new parameter will allow us to use trust in a more accurate way. We consider trust is not static but dynamic and trust values can change along time. Thus, we will also take time into account, using it as a parameter of our model. There is very little work done about the inclusion of time as an influence on trust. We will show the applicability of our model in the scenario of the process of reviewing papers for a conference. Sometimes for these kind of processes the Chair of the conference should first find the suitable reviewers. He can make this selection by using our model. Once the reviewers are selected they send out their reviews to the Chair who can also use our model in order to make the final decision about acceptance of papers.

}, issn = {1571-0661}, doi = {10.1016/j.entcs.2009.07.034}, author = {Isaac Agudo and Carmen Fernandez-Gago and Javier Lopez} } @article {Alcaraz2008a, title = {Gesti{\'o}n segura de redes SCADA}, journal = {Nuevas tendencias en gesti{\'o}n de redes, Nov{\'a}tica}, number = {196}, year = {2008}, month = {December}, pages = {20-25}, publisher = {CEPIS}, abstract = {

En el momento que se introduce en el mercado nuevas tecnolog\ías basadas en entornos distribuidos comienzan a surgir en paralelo nuevos problemas de seguridad en los sistemas SCADA (Supervisory Control and Data Acquisition), los cuales monitorizan y gestionan otras infraestructuras de gran complejidad y escala. Un fallo o una interrupci\ón en uno de sus componentes podr\ía suponer un impacto negativo sobre la funcionalidad de otras infraestructuras, por lo que se hace necesario realizar frecuentes an\álisis de seguridad para as\í mantener actualizado el conocimiento y proveer recomendaciones y/o soluciones para mitigar o evitar futuras ocurrencias, garantizando una gesti\ón de red fiable y siempre disponible.

}, keywords = {An{\'a}lisis de Seguridad, Gesti{\'o}n de red SCADA, Supervisory Control and Data Acquisition Systems}, issn = {0211-2124}, url = {http://www.ati.es/novatica/indice.html$\#$196}, author = {Cristina Alcaraz and Gerardo Fernandez and Rodrigo Roman and Angel Balastegui and Javier Lopez} } @incollection {Roman2008, title = {On the Hardware Implementation Efficiency of Cryptographic Primitives}, booktitle = {Wireless Sensor Network Security}, year = {2008}, publisher = {IOS Press}, organization = {IOS Press}, abstract = {

Security has been proven a crucial factor in the provision of data services and especially in the computer-related environments. While wired and wireless networks come to all sectors of everyday life, security tries to satisfy the growing needs for confidentiality, integrity and non-repudiation. There are many instances of security primitives and each one of them has different requirements in terms of processing power, word size, etc. Therefore, it is important to review the functionality of the less resource-demanding encryption algorithms in order to analyze their theoretical suitability to the existent sensor node hardware. Still, the constraints inherent to the sensor nodes advise against the total dependence on software-based implementations, even more in the case of expensive primitives.

}, isbn = {978-1-58603-813-7}, author = {Rodrigo Roman and Cristina Alcaraz and Nicolas Sklavos}, editor = {Javier Lopez and Jianying Zhou} } @inproceedings {Agudo2008a, title = {A Model for Trust Metrics Analysis}, booktitle = {5th International Conference on Trust, Privacy and Security in Digital Business (TrustBus{\textquoteright}08)}, series = {LNCS}, volume = {5185}, year = {2008}, pages = {28-37}, publisher = {Springer}, organization = {Springer}, abstract = {

Trust is an important factor in any kind of network essential, for example, in the decision-making process. As important as the definition of trust is the way to compute it. In this paper we propose a model for defining trust based on graph theory and show examples of some simple operators and functions that will allow us to compute trust.

}, isbn = {978-3-540-85734-1}, issn = {0302-9743 (Print) 1611-3349 (Online)}, doi = {10.1007/978-3-540-85735-8_4}, author = {Isaac Agudo and Carmen Fernandez-Gago and Javier Lopez} } @article {Alcaraz2008b, title = {Secure Management of SCADA Networks}, journal = {Novatica, New Trends in Network Management}, volume = {9}, number = {6}, year = {2008}, month = {December}, pages = {22-28}, publisher = {Cepis UPGRADE}, abstract = {

When a Supervisory Control and Data Acquisition (SCADA) system monitors and manages other complex infrastructures through the use of distributed technologies, it becomes a critical infrastructure by itself: A failure or disruption in any of its components could implicate a serious impact on the performance of the other infrastructures. The connection with other systems makes a SCADA system more vulnerable against attacks, generating new security problems. As a result, it is essential to perform diverse security analysis frequently in order to keep an updated knowledge and to provide recommendations and/or solutions to mitigate or avoid anomalous events. This will facilitate the existence of a suitable, reliable, and available control network.

}, keywords = {SCADA network management, Security Analysis, Supervisory Control and Data Acquisition Systems}, issn = {1684-5285}, url = {http://www.upgrade-cepis.org/issues/2008/6/up9-6Alcaraz.pdf}, author = {Cristina Alcaraz and Gerardo Fernandez and Rodrigo Roman and Angel Balastegui and Javier Lopez} } @inproceedings {Marquez2008, title = {Secure Real-Time Integration of Services in a OSGi Distributed Environment}, booktitle = {Fourth International Conference on Networked Computing and Advanced Information Management (NCM{\textquoteright}08)}, volume = {1}, year = {2008}, month = {September}, pages = {631-635}, publisher = {IEEE}, organization = {IEEE}, address = {Gyeongju, South Korea}, abstract = {This paper presents a service oriented architecture for real-time integration of services, how to distribute them in a local domain and how to define a secure way of accessing resources using users{\textquoteright} and services{\textquoteright} authorization and authentication. This work take advantage of previous European R amp;D projects focused on del.ivering applications and utilities in embedded real-time environments and the convergence of different worlds like Internet and digital TV.}, keywords = {authentication, authorisation, authorization, digital TV, embedded real-time environments, embedded systems, Internet, message authentication, open systems, OSGi distributed environment, secure real-time integration, service oriented architecture, software architecture}, isbn = {978-0-7695-3322-3}, doi = {10.1109/NCM.2008.173}, author = {Jose Manuel Marquez and Javier Jimenez and Isaac Agudo} } @inproceedings {Alcaraz2007, title = {An{\'a}lisis de primitivas criptogr{\'a}ficas para redes de sensores}, booktitle = {VI Jornadas de Ingenier{\'\i}a Telem{\'a}tica (JITEL{\textquoteright}07)}, year = {2007}, month = {September}, pages = {401-408}, address = {M{\'a}laga (Spain)}, abstract = {

Security in wireless sensor networks is very limited due to highly-constrained hardware of sensor nodes. To protect services is necessary to use secure foundations, known as security primitives, like part of a protocol. Theses primitives must assure at least confidentiality in the communication channel, authentication of the peers involved in an information exchange, and integrity of the messages. There are many primitives such as symmetric encryption, hash functions and public key cryptography, but not all of them can be supported by sensor nodes since require high resource levels, for example memory. This paper contains a deep analysis of available and suitable security primitives for sensor nodes, as well as an analysis of hardware and software implementations. Besides, it has been developed an experiment with two implementations, and it has been created a new and improved version using the optimizations of each.

}, isbn = {978-84-690-6670-6}, url = {http://www.telematica.ws/jitel/2007/}, author = {Cristina Alcaraz and Rodrigo Roman and Javier Lopez} } @inproceedings {Roman2007b, title = {Applicability of Public Key Infrastructures in Wireless Sensor Networks}, booktitle = {European PKI Workshop: Theory and Practice (EuroPKI{\textquoteright}07)}, series = {LNCS}, volume = {4582}, year = {2007}, month = {June}, pages = {313-320}, publisher = {Springer}, organization = {Springer}, address = {Mallorca (Spain)}, abstract = {

Wireless Sensor Networks (WSN) are becoming a key technology in the support of pervasive and ubiquitous services. The previous notion of PKC is too expensive for WSN has changed partially due to the existence of new hardware and software prototypes based on Elliptic Curve Cryptography and other PKC primitives. Then, it is necessary to analyze whether it is both feasible and convenient to have a Public Key Infrastructure for sensor networks that would allow the creation of PKC-based services like Digital Signatures.

}, keywords = {Public Key Cryptography, Public Key Infrastructure, wireless sensor networks}, isbn = {978-3-540-73407-9}, issn = {0302-9743 (Print) 1611-3349 (Online)}, doi = {10.1007/978-3-540-73408-6_22}, url = {http://www.springerlink.com/content/q4l10ww348010131/}, author = {Rodrigo Roman and Cristina Alcaraz} } @inproceedings {Agudo2007a, title = {Attribute delegation in ubiquitous environments}, booktitle = {3rd international conference on Mobile multimedia communications (MobiMedia {\textquoteright}07)}, year = {2007}, pages = {43:1{\textendash}43:6}, publisher = {ICST}, organization = {ICST}, address = {Nafpaktos, Greece}, abstract = {

When delegation is implemented using the attribute certificates in a Privilege Management Infrastructure (PMI), this one reaches a considerable level of distributed functionality. However, the approach is not flexible enough for the requirements of ubiquitous environments. Additionally, the PMI can become a too complex solution for devices such as smartphones and PDAs, where resources are limited. In this work, we solve the previous limitations by defining a second class of attributes, called domain attributes, which are managed directly by users and are not right under the scope of the PMI, thus providing a light solution for constrained devices. The two classes of attributes are related by defining a simple ontology. We also introduce in the paper the concept of Attribute Federation which is responsible for supporting domain attributes and the corresponding ontology.

}, isbn = {978-963-06-2670-5}, author = {Isaac Agudo and Javier Lopez and Jose A. Montenegro} } @article {JavierLopez2007, title = {On the deployment of a real scalable delegation service}, journal = {Information Security Technical Report}, volume = {12}, number = {3}, year = {2007}, month = {Jun 2007}, pages = {139-147}, publisher = {Elsevier}, abstract = {

This paper explains the evolution of the concept of delegation since its first references in the context of distributed authorization to the actual use as a fundamental part of a privilege management architecture. The work reviews some of the earliest contributions that pointed out the relevance of delegation when dealing with distributed authorization, in particular we comment on PolicyMaker and Keynote, and also on SDSI/SPKI. Then, we elaborate on Federation as a particular case of delegation, and remark the importance given to federation by the industry. Finally, the paper discusses about privilege management infrastructures, introducing a new mechanism to extend their functionality using advanced delegation services.

}, issn = {1363-4127}, doi = {10.1016/j.istr.2007.05.008}, author = {Javier Lopez and Isaac Agudo and Jose A. Montenegro} } @inproceedings {Agudo2007, title = {Implementation aspects of a delegation system}, booktitle = {3rd international conference on Mobile multimedia communications (MobiMedia {\textquoteright}07)}, year = {2007}, pages = {50:1{\textendash}50:6}, publisher = {ICST}, organization = {ICST}, address = {Nafpaktos, Greece}, abstract = {

In this paper we simulate an authorization and delegation system using knowledge based technology. This proposal is part of a visual tool that is intended to be an implementation of the theoretical model weighted trust graph (WTG). A brief description of WTG Model and its associated tool is included in the text. In essence, the model is based on the inclusion of real numbers between zero and one in certificates to represent the trust level between the entities involved in them. This trust level is used to control delegation. Moreover, attributes from di_erent domains may be interrelated, so attribute delegation is also taken into account. The proposed Simulation Engine supports one directional and bidirectional search algorithms.

}, isbn = {978-963-06-2670-5}, author = {Isaac Agudo and Javier Lopez and Jose A. Montenegro} } @incollection {Lopez2007, title = {On the Protection and Technologies of Critical Information Infrastructures.}, booktitle = {On Foundations of Security Analysis and Design IV, FOSAD 2006/2007, Springer}, series = {LNCS}, volume = {4677}, year = {2007}, note = {

10.1007/978-3-540-74810-6_6

}, pages = {160-182}, abstract = {

Critical Infrastructures are complex and highly interconnected systems that are crucial for the well-being of the society. Any type of failure can cause significant damage, affecting one or more sectors due to their inherent interdependency. Not only the infrastructures are critical, but also the information infrastructures that manage, control and supervise them. Due to the seriousness of the consequences, the protection of these critical (information) infrastructures must have the highest priority. It is the purpose of this book chapter to review and discuss about these infrastructures, to explain their elements, and to highlight their research and development issues. This chapter will also discuss the role of Wireless Sensor Network (WSN) technology in the protection of these infrastructures.

}, keywords = {Critical Information Infrastructure Protection, wireless sensor networks}, issn = {0302-9743}, doi = {10.1007/978-3-540-74810-6_6}, url = {http://dx.doi.org/10.1007/978-3-540-74810-6_6}, author = {Javier Lopez and Cristina Alcaraz and Rodrigo Roman} } @incollection {Najera2007, title = {RFID: Technological Issues and Privacy Concerns}, booktitle = {Digital Privacy: Theory, Technologies, and Practices}, year = {2007}, month = {December}, pages = {285-306}, publisher = {Auerbach Publications}, organization = {Auerbach Publications}, isbn = {1420052179}, author = {Pablo Najera and Javier Lopez}, editor = {A. Acquisti and Stefanos Gritzalis and C. Lambrinoudakis and Sabrina De Capitani di Vimercati} } @article {Roman2007a, title = {The Role of Wireless Sensor Networks in the Area of Critical Information Infrastructure}, journal = {Information Security Technical Report}, volume = {12}, number = {1}, year = {2007}, pages = {24-31}, publisher = {Elsevier}, abstract = {

Critical Infrastructures, such as energy, banking, and transport, are an essential pillar to the well-being of the national and international economy, security and quality of life. These infrastructures are dependent on a spectrum of highly interconnected information infrastructures for their smooth, reliable and continuous operation. The field of protecting such Critical Information Infrastructures, or CIIP, faces numerous challenges, such as managing the secure interaction between peers, assuring the resilience and robustness of the overall system, and deploying warning and alert systems, amongst others. In this tapestry of CIIP, Wireless Sensor Networks can be used as an invaluable tool due to their intelligent distributed control capabilities, alongside with their capability to work under severe conditions. In this paper, we justify why Wireless Sensor Networks technology is suitable for providing security for these scenarios, describing both their advantages and research issues and their role in the overall scheme of protecting the Critical Information Infrastructures.

}, keywords = {Critical Information Infrastructure Protection, Network Security, wireless sensor networks}, issn = {1363-4127}, doi = {10.1016/j.istr.2007.02.003}, url = {http://www.sciencedirect.com/science/article/B6VJC-4N6NK24-1/2/b1462973afe70af30a10b955d96ccbb6}, author = {Rodrigo Roman and Cristina Alcaraz and Javier Lopez} } @article {Roman2007, title = {A Survey of Cryptographic Primitives and Implementations for Hardware-Constrained Sensor Network Nodes}, journal = {Mobile Networks and Applications}, volume = {12}, number = {4}, year = {2007}, month = {August}, pages = {231-244}, publisher = {Springer}, abstract = {

In a wireless sensor network environment, a sensor node is extremely constrained in terms of hardware due to factors such as maximizing lifetime and minimizing physical size and overall cost. Nevertheless, these nodes must be able to run cryptographic operations based on primitives such as hash functions, symmetric encryption and public key cryptography in order to allow the creation of secure services. Our objective in this paper is to survey how the existing research-based and commercial-based sensor nodes are suitable for this purpose, analyzing how the hardware can influence the provision of the primitives and how software implementations tackles the task of implementing instances of those primitives. As a result, it will be possible to evaluate the influence of provision of security in the protocols and applications/scenarios where sensors can be used.

}, keywords = {Cryptography, Hardware, Sensor Networks}, issn = {1383-469X}, doi = {10.1007/s11036-007-0024-2}, url = {http://www.springerlink.com/content/3785k818327456gq/}, author = {Rodrigo Roman and Cristina Alcaraz and Javier Lopez} } @inproceedings {Alcaraz2006, title = {Applying Key Infrastructures for Sensor Networks in {CIP/CIIP} Scenarios}, booktitle = {1st International Workshop on Critical Information Infrastructures Security (CRITIS{\textquoteright}06)}, series = {LNCS}, volume = {4347}, year = {2006}, pages = {166-178}, publisher = {Springer Berlin / Heidelberg}, organization = {Springer Berlin / Heidelberg}, abstract = {

It is commonly agreed that Wireless Sensor Networks (WSN) is one of the technologies that better fulfills features like the ones required by Critical (Information) Infrastructures. However, a sensor network is highly vulnerable against any external or internal attacks, thus network designers must know which are the tools that they can use in order to avoid such problems. In this paper we describe in detail a procedure (the KMS Guidelines), developed under our CRISIS project, that allows network designers to choose a certain Key Management System, or at least to know which protocol need to improve in order to satisfy the network requirements.

}, keywords = {Critical Information Infrastructures, Key Infrastructures, Key Management, Sensor Networks}, issn = {0302-9743 (Print) 1611-3349 (Online)}, doi = {10.1007/11962977_14}, url = {http://www.springerlink.com/content/2458827107n14870/}, author = {Cristina Alcaraz and Rodrigo Roman} } @inproceedings {IsaacAgudo2006, title = {Attributes Delegation Based on Ontologies and Context Information}, booktitle = {10th IFIP TC-6 TC-11 International Conference on Communications and Multimedia on Security (CMS{\textquoteright}06)}, series = {LNCS}, volume = {4237}, year = {2006}, month = {October}, pages = {54-66}, publisher = {Springer}, organization = {Springer}, address = {Heraklion, Crete}, abstract = {

This paper presents a model for delegation based on partial orders, proposing the subclass relation in OWL as a way to represent the partial orders. Delegation and authorization decisions are made based on the context. In order to interact with the context, we define the Type of a credential as a way to introduce extra information regarding context constraints. When reasoning about delegation and authorization relationships, our model benefits from partial orders, defining them over entities, attributes and the credential type. Using these partial orders, the number of credentials required is reduced. It also classifies the possible criteria for making authorization decisions based on the context, in relation to the necessary information.

}, isbn = {978-3-540-47820-1}, issn = {0302-9743 (Print) 1611-3349 (Online)}, doi = {10.1007/11909033_6}, author = {Isaac Agudo and Javier Lopez and Jose A. Montenegro} } @inproceedings {Agudo2006a, title = {Graphical Representation of Authorization Policies for Weighted Credentials}, booktitle = {11th Australasian Conference on Information Security and Privacy (ACISP{\textquoteright}06)}, series = {LNCS}, volume = {4058}, year = {2006}, pages = {383-394}, publisher = {Springer}, organization = {Springer}, address = {Melbourne, Australia}, abstract = {

This paper elaborates on a solution to represent authorization and delegation in a graphical way, allowing users to better interpret delegation relationships. We make use of Weighted Trust Graph (WTG) as an instrument to represent delegation and authorization, extending it to cope with more complicated concepts, and providing a graphical representation of the level of confidence that exists between two entities regarding a resource or attribute. We represent the level of confidence for each pair of entities as a point in an axis diagram, as a set of points, or as a set of triangular regions depending on the accuracy we need. Then, we use the same diagram to represent the set of acceptable confidence level, that we call authorization policy set. In this way, a single diagram can be used to decide about authorization, thus providing a powerful tool for systems in which interaction of users is needed.

}, isbn = {978-3-540-35458-1}, issn = {0302-9743 (Print) 1611-3349 (Online)}, doi = {10.1007/11780656_32}, author = {Isaac Agudo and Javier Lopez and Jose A. Montenegro} } @inproceedings {IsaacAgudo2006a, title = {Pol{\'\i}ticas de delegaci{\'o}n para credenciales ponderadas y su representaci{\'o}n gr{\'a}fica}, booktitle = {IX Reuni{\'o}n Espa{\~n}ola sobre Criptolog{\'\i}a y Seguridad de la informaci{\'o}n (RECSI{\textquoteright}06)}, year = {2006}, month = {Septiembre}, pages = {311-322}, address = {Barcelona, Spain}, isbn = {84-9788-502-3}, author = {Isaac Agudo and Javier Lopez and Jose A. Montenegro} } @inproceedings {IsaacAgudo2005a, title = {Delegation Perspective of Practical Authorization Schemes}, booktitle = {Fifth International Network Conference (INC{\textquoteright}05)}, year = {2005}, pages = {157-164}, address = {Samos Island, Greece}, isbn = {960-7475-32-1}, author = {Isaac Agudo and Javier Lopez and Jose A. Montenegro and Eiji Okamoto and Ed Dawson} } @article {IsaacAgudo2005, title = {A Graphical Delegation Solution for X.509 Attribute Certificates}, journal = {ERCIM News}, number = {63}, year = {2005}, month = {October}, pages = {33-34}, publisher = {ERCIM}, issn = {0926-4981}, author = {Isaac Agudo and Javier Lopez and Jose A. Montenegro} } @inproceedings {IsaacAgudo2005b, title = {A Representation Model of Trust Relationships with Delegation Extensions}, booktitle = {3th International Conference on Trust Management (iTRUST{\textquoteright}05)}, series = {LNCS}, volume = {3477}, year = {2005}, month = {May}, pages = {9-22}, publisher = {Springer}, organization = {Springer}, address = {Versailles, France}, abstract = {

Logic languages establish a formal framework to solve authorization and delegation conflicts. However, we consider that a visual representation is necessary since graphs are more expressive and understandable than logic languages. In this paper, and after overviewing previous works using logic languages, we present a proposal for graph representation of authorization and delegation statements. Our proposal is based on Varadharajan et al. solution, though improve several elements of that work. We also discuss about the possible implementation of our proposal using attribute certificates.

}, isbn = {978-3-540-26042-4}, issn = {0302-9743 (Print) 1611-3349 (Online)}, doi = {10.1007/11429760_9}, author = {Isaac Agudo and Javier Lopez and Jose A. Montenegro} } @inproceedings {1735, title = {Especificaci{\'o}n formal y verificaci{\'o}n de requisitos de Seguridad}, booktitle = {VIII Reuni{\'o}n Espa{\~n}ola sobre Criptolog{\'\i}a y Seguridad de la Informaci{\'o}n (VIII RECSI)}, year = {2004}, month = {Sep 2004}, pages = {225-235}, address = {Madrid (Spain)}, isbn = {84-7978-650-7}, author = {Isaac Agudo and Javier Lopez and Juan J. Ortega} } @inproceedings {Agudo2004, title = {Specification and formal verification of security requirements}, booktitle = {5th international conference on Computer systems and technologies (CompSysTech {\textquoteright}04)}, year = {2004}, pages = {1-6}, publisher = {ACM}, organization = {ACM}, address = {Rousse, Bulgaria}, abstract = {With the grown of internet and distributed applications, security requirements are going inherent to the software development process. Each time one communicates with some other one there are relevant security risk that must be taken in account. This is what is happening in the new soft-ware applications using client/server architecture. We propose including security requirements at the top level of development process, together with functional requirements because they are much related. With this information we are able to extract all communication protocols that are involved in our application and their associated security goals. This is the input to a verification phase in which we look for security flaws. The last step, and the more useful (and the not yet finished) is to use this information to modify our initial specification at the top level of the development process}, isbn = {954-9641-38-4}, doi = {10.1145/1050330.1050440}, author = {Isaac Agudo and Javier Lopez} } @inproceedings {JavierAreitio2001, title = {An{\'a}lisis, Dise{\~n}o e Implementaci{\'o}n de un Entorno Escalable de Comercio-e con Seguridad Telem{\'a}tica Adaptable Basada en PKI}, booktitle = {I Simposio Espa{\~n}ol de Comercio Electr{\'o}nico (SEC{\textquoteright}01)}, year = {2001}, month = {Octubre}, pages = {145-160}, address = {M{\'a}laga, Espa}, abstract = {

La presente ponencia aborda el desarrollo de un entorno seguro escalable para el Comercio Electr\ónico. Se ha tratado la cuesti\ón en dos fases: primero, idear un prototipo generalizado distribuido seguro formado por diferentes entidades gen\éricas con el objetivo de permitir que los clientes realicen sus compras y transacciones bancarias con un nivel de seguridad escalable; y en segundo lugar, implantar en la pr\áctica un prototipo de grado de escalabilidad reducido como modelo emp\írico.

}, author = {Javier Areitio and Lorenzo Mart{\'\i}nez and Javier Lopez and Jose A. Montenegro} } @article {JavierAreitio2000, title = {Horizontes y Tendencias de Seguridad en Internet}, journal = {Nov{\'a}tica}, volume = {145}, year = {2000}, pages = {65-71}, abstract = {

El comercio electr\ónico est\á llamado a ser el fen\ómeno de mayor importancia en el futuro de Internet. Entre sus aplicaciones se encuentran las compras en l\ínea, la banca electr\ónica, la tele-educaci\ón, los casinos virtuales, los servicios de pago por visi\ón y v\ídeo bajo demanda, etc. Desde el punto de vista de la Seguridad, estas aplicaciones presentan una serie de nuevos requisitos que van a imponer un gran esfuerzo investigador a corto y medio plazo. En este art\ículo se presentan algunos de los m\ás importantes, como la administraci\ón de la confianza, la utilizaci\ón de pagos electr\ónicos, la necesidad de la protecci\ón de la propiedad intelectual, los servicios de protecci\ón de privacidad y anonimato, y la autonom\ía de c\ódigo y la detecci\ón de fraudes, identific\ándose las \áreas de investigaci\ón relacionadas.

}, issn = {0211-2124}, author = {Javier Areitio and Javier Lopez and Jose M. Troya} } @inproceedings {JavierAreitio2000a, title = {Mecanismo de Seguridad de Bajo Costo para Micropagos}, booktitle = {VI Reunion Espa{\~n}ola de Criptolog{\'\i}a y Seguridad de la Informaci{\'o}n (VI RECSI)}, year = {2000}, month = {Septiembre}, pages = {193-200}, address = {La Laguna, Espa}, abstract = {
La presente comunicaci\ón presenta un mecanismo de micropagos flexible, de bajo costo que puede utilizarse para realizar pagos en l\ínea entre el cliente y el vendedor y fuera de l\ínea con el agente de negocios. Este mecanismo evita grandes almacenamientos de datos y c\álculos largos. Se puede implantar en software para el cliente y en hardware/software para el vendedor.\ \ 
}, author = {Javier Areitio and Javier Lopez} } @article {JavierAretitio1999, title = {Contribuciones de la Tecnolog{\'\i}a de Detecci{\'o}n y Respuesta a Intrusiones y Ataques a la Construcci{\'o}n de la Confianza}, journal = {Nov{\'a}tica}, volume = {141}, year = {1999}, pages = {24-27}, author = {Javier Areitio and Javier Lopez} } @inproceedings {JavierLopez1999d, title = {Problem{\'a}tica de Seguridad para el Comercio Electr{\'o}nico en el Sector Tur{\'\i}stico}, booktitle = {I Congreso Nacional Turismo y Tecnolog{\'\i}a de la Informaci{\'o}n y las Comunicaciones (TURITEC{\textquoteright}99)}, year = {1999}, month = {Septiembre}, pages = {99-110}, abstract = {

Uno de los servicios que cada d\ía cobra m\ás importancia y que promete un cambio radical para las empresas es el comercio electr\ónico en Internet, pero tradicionalmente las empresas relacionadas con el turismo s\ólo han empleado la red para darse a conocer y ofertar sus productos. La raz\ón esencial es la desconfianza que existe sobre la seguridad de las transacciones llevadas a cabo en la red. La criptograf\ía de clave p\ública proporciona servicios adecuados para garantizar la seguridad de esas transacciones. Pero en la actualidad, algunos de esos servicios est\án menos desarrollados que otros; un ejemplo de ellos es el servicio de No-Repudio. En este art\ículo se estudian distintas formas de ofrecer servicios de no-repudio y se analizan sus ventajas y desventajas en funci\ón de las necesidades del entorno en que se utilicen.

}, author = {Javier Lopez and Javier Areitio and Felipe Rosello} }