Fabien Laguillaumie

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The concept of Designated Verifier Signatures (DVS) was introduced by Jakobsson, Sako and Impagliazzo at Eurocrypt’96. These signatures are intended to a specific verifier, who is the only one able to check their validity. In this context, we formalize the notion of privacy of signer’s identity which captures the strong designated verifier property(More)
Designated verifier signatures were introduced in the middle of the 90’s by Jakobsson, Sako and Impagliazzo, and independenty patended by Chaum as private signatures. In this setting, a signature can only be verified by a unique and specific user. At Crypto’03, Desmedt suggested the problem of generalizing the designated verifier signatures. In this case, a(More)
Attribute-based cryptography has emerged in the last years as a promising primitive for digital security. For instance, it provides good solutions to the problem of anonymous access control. In a ciphertextpolicy attribute-based encryption scheme, the secret keys of the users depend on their attributes. When encrypting a message, the sender chooses which(More)
Ring signatures were introduced by Rivest, Shamir, and Tauman in 2001. These signatures allow a signer to anonymously authenticate a message on behalf of a group of his choice. This concept was then extended by Bresson, Stern, and Szydlo into <i>t</i>-out-of-<i>N</i> (threshold) ring signatures in 2002. We propose in this article a generalization of Stern's(More)
Attribute-based cryptography is a natural solution for fine-grained access control with respect to security policies. In the case of attribute-based signatures (ABS), users obtain from an authority their secret keys as a function of the attributes they hold, with which they can later sign messages for any predicate satisfied by their attributes. A verifier(More)
Universal designated verifier signatures (UDVS) were introduced in 2003 by Steinfeld et al. to allow signature holders to monitor the verification of a given signature in the sense that any plain signature can be publicly turned into a signature which is only verifiable by some specific designated verifier. Privacy issues, like non-dissemination of digital(More)
Sanitizable signatures allow a designated entity to modify some specific parts of a signed message and to produce a new signature of the resulting message without any interaction with the original signer. In this paper, we extend these sanitizable signatures to formally introduce trapdoor sanitizable signatures. In this concept, the power of sanitization is(More)
In 1996, Jakobsson, Sako and Impagliazzo and, on the other hand, Chaum proposed the notion of designated verifier signature to solve some of the intrinsic problems of undeniable signatures. The generalization of this concept, suggested by Desmedt at Crypto’03’s rump session, was formally investigated by Laguillaumie and Vergnaud at ICICS’04 as(More)
Miller’s algorithm is at the heart of all pairing-based cryptosystems since it is used in the computation of pairing such as that of Weil or Tate and their variants. Most of the optimizations of this algorithm involve elliptic curves of particular forms, or curves with even embedding degree, or having an equation of a special form. Other improvements(More)