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Conference papers

Universally Convertible Directed Signatures

Abstract : Many variants of Chaum and van Antwerpen's undeniable signatures have been proposed to achieve specific properties desired in real-world applications of cryptography. Among them, directed signatures were introduced by Lim and Lee in 1993. Directed signatures differ from the well-known confirmer signatures in that the signer has the simultaneous abilities to confirm, deny and individually convert a signature. The universal conversion of these signatures has remained an open problem since their introduction in 1993. This paper provides a positive answer to this quest by showing a very efficient design for universally convertible directed signatures (UCDS) both in terms of computational complexity and signature size. Our construction relies on the so-called xyz-trick applicable to bilinear map groups. We define proper security notions for UCDS schemes and show that our construction is secure, in the random oracle model, under computational assumptions close to the CDH and DDH assumptions. Finally, we introduce and realize traceable universally convertible directed signatures where a master tracing key allows to link signatures to their direction.
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Contributor : Fabien Laguillaumie Connect in order to contact the contributor
Submitted on : Saturday, February 18, 2006 - 10:41:12 AM
Last modification on : Friday, February 4, 2022 - 3:22:42 AM
Long-term archiving on: : Saturday, April 3, 2010 - 10:29:04 PM



  • HAL Id : inria-00001121, version 1



Fabien Laguillaumie, Pascal Paillier, Damien Vergnaud. Universally Convertible Directed Signatures. Asiacrypt 2005, Dec 2005, Chennai, India. ⟨inria-00001121⟩



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