Gradually Convertible Undeniable Signatures

14 years 19 days ago
Gradually Convertible Undeniable Signatures
In 1990, Boyar, Chaum, Damg˚ard and Pedersen introduced convertible undeniable signatures which limit the self-authenticating property of digital signatures but can be converted by the signer to ordinary signatures. Michels, Petersen and Horster presented, in 1996, an attack on the El Gamal-based seminal scheme of Boyar et al. and proposed a repaired version without formal security analysis. In this paper, we modify their protocol so that it becomes a generic one and it provides an advanced feature which permits the signer to universally convert achronously all signatures pertaining to a specific time period. We supply a formal security treatment of the modified scheme: we prove, in the generic group model, that the protocol is existentially unforgeable and anonymous under chosen message attacks, assuming new assumptions (though reasonable) on the underlying hash function.
Laila El Aimani, Damien Vergnaud
Added 06 Jun 2010
Updated 06 Jun 2010
Type Conference
Year 2007
Where ACNS
Authors Laila El Aimani, Damien Vergnaud
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