Vicente Benjumea

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We present a semantic extension to X.509 certificates that allows incorporating new anonymity signature schemes into the X.509 framework. This fact entails advantages to both components. On the one hand, anonymous signature schemes benefit from all the protocols and infrastructure that the X.509 framework provides. On the other hand, the X.509 framework(More)
This paper focus on two security services for internet applications: authorization and anonymity. Traditional authorization solutions are not very helpful for many of the Internet applications; however, attribute certificates proposed by ITU-T seems to be well suited and provide adequate solution. On the other hand, special attention is paid to the fact(More)
Purpose – To provide a cryptographic protocol for anonymously accessing services offered on the web. Such anonymous accesses can be disclosed or traced under certain conditions. Design/methodology/approach – The “traceable signature” scheme was used in conjunction with the “privilege management infrastructure”. Findings – The cryptographic primitive(More)
This paper presents fair traceable multi-group signatures (FTMGS), which have enhanced capabilities, compared to group and traceable signatures, that are important in real world scenarios combining accountability and anonymity. The main goal of the primitive is to allow multiple groups that are managed separately (managers are not even aware of the other(More)
In this paper we have defined an open framework to support open distributed applications where anonymous transactions based on user privileges play an important role. The goal of the framework is to provide a basis to the application level, and is presented from an open and general perspective where many different implementation schemes can fit. Moreover,(More)
DRM technologies include a range of functions to support the management of intellectual property for digital resources, such as expression of rights and obligations, description, identification, trading, protection, monitoring and tracking of digital content. This paper presents the EC-GATE system, a general framework capable of supporting very(More)
The paper shows an implementation model to support the execution of the Basic Andorra Model on distributed memory systems. A model for exploiting dependent AND parallelism in Prolog programs on distributed systems is also proposed, as well as the way in which it has to be combined with an OR parallel model. A mechanism for dealing with unbound variables in(More)
This paper shows a multisequential model to exploit OR parallelism on distributed memory systems. It presents an implementation of the incremental copy mechanism oriented to distributed systems and a novel distributed scheduler is also proposed. WAM modifications to support the proposed model are very simple. The system has been implemented on a 16(More)