@article {rios2015, title = {Probabilistic receiver-location privacy protection in wireless sensor networks}, journal = {Information Sciences}, volume = {321}, year = {2015}, month = {07/2015}, pages = {205 - 223}, publisher = {Elsevier}, abstract = {

Wireless sensor networks (WSNs) are continually exposed to many types of attacks. Among these, the attacks targeted at the base station are the most devastating ones since this essential device processes and analyses all traffic generated in the network. Moreover, this feature can be exploited by a passive adversary to determine its location based on traffic analysis. This receiver-location privacy problem can be reduced by altering the traffic pattern of the network but the adversary may still be able to reach the base station if he gains access to the routing tables of a number of sensor nodes. In this paper we present HISP-NC (Homogenous Injection for Sink Privacy with Node Compromise protection), a receiver-location privacy solution that consists of two complementary schemes which protect the location of the base station in the presence of traffic analysis and node compromise attacks. The HISP-NC data transmission protocol prevents traffic analysis by probabilistically hiding the flow of real traffic with moderate amounts of fake traffic. Moreover, HISP-NC includes a perturbation mechanism that modifies the routing tables of the nodes to introduce some level of uncertainty in attackers capable of retrieving the routing information from the nodes. Our scheme is validated both analytically and experimentally through extensive simulations.

}, keywords = {node capture, privacy, security, traffic analysis, wireless sensor networks}, issn = {0020-0255}, doi = {10.1016/j.ins.2015.01.016}, author = {Ruben Rios and Jorge Cuellar and Javier Lopez} } @incollection {ruben2014a, title = {Location Privacy in WSNs: Solutions, Challenges, and Future Trends}, booktitle = {Foundations of Security Analysis and Design VII}, volume = {8604}, number = {LNCS}, year = {2014}, pages = {244-282}, publisher = {Springer}, organization = {Springer}, abstract = {

Privacy preservation is gaining popularity in Wireless Sensor Network (WSNs) due to its adoption in everyday scenarios. There are a number of research papers in this area many of which concentrate on the location privacy problem. In this paper we review and categorise these solutions based on the information available to the adversary and his capabilities. But first we analyse whether traditional anonymous communication systems conform to the original requirements of location privacy in sensor networks. Finally, we present and discuss a number of challenges and future trends that demand further attention from the research community.

}, keywords = {Location Privacy, survey, traffic analysis, wireless sensor networks}, isbn = {978-3-319-10081-4}, issn = {0302-9743}, doi = {10.1007/978-3-319-10082-1_9}, author = {Ruben Rios and Javier Lopez and Jorge Cuellar} } @inproceedings {Lopez2014prl, title = {Preserving Receiver-Location Privacy in Wireless Sensor Networks}, booktitle = {Information Security Practice and Experience (ISPEC 2014)}, volume = {8434}, year = {2014}, month = {05/2014}, pages = {15-27}, publisher = {Springer}, organization = {Springer}, address = {Fuzhou, China}, abstract = {

Wireless sensor networks (WSNs) are exposed to many different types of attacks. Among these, the most devastating attack is to compromise or destroy the base station since all communications are addressed exclusively to it. Moreover, this feature can be exploited by a passive adversary to determine the location of this critical device. This receiver-location privacy problem can be reduced by hindering traffic analysis but the adversary may still obtain location information by capturing a subset of sensor nodes in the field. This paper addresses, for the first time, these two problems together in a single solution

}, keywords = {Location Privacy, node capture, traffic analysis, wireless sensor networks}, isbn = {978-3-319-06319-5}, issn = {0302-9743}, doi = {10.1007/978-3-319-06320-1_3}, url = {http://link.springer.com/chapter/10.1007/978-3-319-06320-1_3$\#$}, author = {Javier Lopez and Ruben Rios and Jorge Cuellar} } @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 {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} } @article {Rios2012a, title = {(Un)Suitability of Anonymous Communication Systems to WSN}, journal = {IEEE Systems Journal}, volume = {7}, number = {2}, year = {2013}, month = {Jun 2013}, pages = {298 - 310}, publisher = {IEEE Systems Council}, abstract = {

Anonymous communication systems have been extensively studied by the research community to prevent the disclosure of sensitive information from the analysis of individuals{\textquoteright} traffic patterns. Many remarkable solutions have been developed in this area, most of which have proven to be effective in the protection of user privacy against different types of attacks. Recently, the privacy preservation problem has also been considered in the realm of wireless sensor networks (WSNs) due to their imminent adoption in real-world scenarios. A special challenge that arises from the analysis of the flow of sensor nodes{\textquoteright} communications is the location privacy problem. In this work we concentrate on analyzing the suitability of traditional anonymous communication systems originally designed for the Internet to the original scenario of sensor networks. The results show that, in most cases, traditional solutions do not provide the adequate protection means for the particular problem of location privacy, while other solutions are too resource-consuming for the restricted capabilities of sensor nodes.

}, keywords = {Anonymous communication, Location Privacy, wireless sensor networks}, issn = {1932-8184}, doi = {10.1109/JSYST.2012.2221956}, author = {Ruben Rios and Javier Lopez} } @article {Galindo2010, title = {On the Energy Cost of Authenticated Key Agreement in Wireless Sensor Networks}, journal = {Wireless Communications and Mobile Computing}, volume = {12}, year = {2012}, month = {Jan 2012}, pages = {133-143}, publisher = {Wiley}, abstract = {

Wireless sensors are battery-powered devices which are highly constrained in terms of computational capabilities, memory and communication bandwidth. While battery life is their main limitation, they require considerable energy to communicate data. Due to this, it turns out that the energy saving of computationally inexpensive primitives (like symmetric key cryptography (SKC)) can be nullified by the bigger amount of data they require to be sent. In this work, we study the energy cost of key agreement protocols between peers in a network using asymmetric key cryptography. Our main concern is to reduce the amount of data to be exchanged, which can be done by using special cryptographic paradigms like identity-based and self-certified cryptography. The main news is that an intensive computational primitive for resource-constrained devices, such as non-interactive identity-based authenticated key exchange, performs comparably or even better than traditional authenticated key exchange (AKE) in a variety of scenarios. Moreover, protocols based in this primitive can provide better security properties in real deployments than other simple protocols based on symmetric cryptography. Our findings illustrate to what extent the latest implementation advancements push the efficiency boundaries of public key cryptography (PKC) in wireless sensor networks (WSNs).

}, keywords = {identity-based key agreement, key distribution, pairings, underwater wireless sensor networks, wireless sensor networks}, issn = {1530-8669}, doi = {10.1002/wcm.894}, url = {http://dx.doi.org/10.1002/wcm.894}, author = {David Galindo and Rodrigo Roman and Javier Lopez} } @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} } @article {Rios2011b, title = {Exploiting Context-Awareness to Enhance Source-Location Privacy in Wireless Sensor Networks}, journal = {The Computer Journal}, volume = {54}, year = {2011}, month = {Sept 2011}, pages = {1603-1615}, publisher = {Oxford University Press}, abstract = {

The source-location privacy problem in Wireless Sensor Networks has been traditionally tackled by the creation of random routes for every packet transmitted from the source nodes to the base station. These schemes provide a considerable protection level at a high cost in terms of message delivery time and energy consumption. This overhead is due to the fact that the data routing process is done in a blind way, without knowledge about the location of the attacker. In this work we propose the Context-Aware Location Privacy (CALP) approach, which takes advantage of the ability of sensor nodes to perceive the presence of a mobile adversary in their vicinity in order to transmit data packets in a more energy-efficient and privacy-preserving manner. In particular, we apply the concepts of CALP to the development of a shortest-path CALP routing algorithm. A permissive and a strict version of the protocol are studied for different adversarial models and the proposed schemes are evaluated through simulation experiments in terms of privacy protection and energy consumption. Finally, we present the conclusions of the paper as well as possible extensions of this work.

}, keywords = {Context-Awareness, Location Privacy, wireless sensor networks}, issn = {0010-4620}, doi = {10.1093/comjnl/bxr055}, author = {Ruben Rios and Javier Lopez} } @inproceedings {Roman2008b, title = {KeyLED - Transmitting Sensitive Data over out-of-band Channels in Wireless Sensor Networks}, booktitle = {5th IEEE International Conference on Mobile Ad Hoc and Sensor Systems (MASS{\textquoteright}08)}, year = {2008}, month = {September}, pages = {796-801}, publisher = {IEEE}, organization = {IEEE}, address = {Atlanta (USA)}, abstract = {

An out-of-band (OoB) channel can be defined as an extra channel, different from the main wireless channel, that has additional security properties. They are specially suitable for protecting spontaneous interactions and exchanging sensitive data between previously unknown devices. Due to the vulnerable nature of wireless sensor networks (WSN), these kind of channels might be useful for protecting certain sensor network operations. In this paper we analyze the applicability of out-of-band channels to wireless sensor networks, and specify why an optical channel should be a good candidate for implementing an extra channel in sensor nodes. Also, we analyze how the existing security threats may affect this type of channel. Finally, the suitability and usability of optical channels for sensor networks is demonstrated by means of a prototype.

}, keywords = {Out-of-Band Channel, security, wireless sensor networks}, isbn = {978-1-4244-2574-7}, doi = {10.1109/MAHSS.2008.4660128}, author = {Rodrigo Roman and Javier Lopez} } @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} } @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} }