    @inproceedings {Roman2005a,
	title = {Protecci{\'o}n contra el Spam Utilizando Desaf{\'\i}os a Priori},
	booktitle = {V Jornadas de Ingenier{\'\i}a Telem{\'a}tica (JITEL{\textquoteright}05)},
	year = {2005},
	month = {September},
	pages = {375-382},
	address = {Vigo (Spain)},
	abstract = {<p>Spam is considered to be one of the biggest problems in messaging systems. In the area of email Spam, A high number of anti-spam schemes have been proposed and deployed, but the problem has yet been well addressed. In this paper, we introduce a new scheme, called pre-challenge scheme, which avoids problems that exists in other schemes such as delay of service and denial of service. Some new mechanisms are employed to reach a good balance between security against Spam and convenience to email users. In addition, our scheme can be used for protecting other types of messaging systems, such as Instant Messaging (IM) and Blogs, against Spam.</p>
},
	author = {Rodrigo Roman and Javier Lopez and Jianying Zhou}
}
