Cryptology ePrint Archive: Report 2004/190

Distributed Ring Signatures for Identity-Based Scenarios

Javier Herranz and Germ\'an S\'aez

Abstract: In a ring signature scheme, a signer in a subset (or {\it ring}) of potential signers produces a signature of a message in such a way that the receiver can verify that the signature comes from a member of the ring, but cannot know which member has actually signed.

In this work, we extend this concept to that of distributed ring signatures, where a subset of users cooperate to compute a distributed anonymous signature on a message, on behalf of a family of subsets. We propose two schemes, one for general families of subsets, and a more efficient one for threshold families of subsets. The security of both proposals is formally proved, assuming the hardness of the Computational Diffie-Hellman problem.

Our two schemes run in an identity-based scenario, where public keys of the users can be derived from their identities. This fact avoids the necessity of digital certificates, and therefore allows more efficient implementations of such systems.

Category / Keywords: cryptographic protocols / Identity-based cryptography, Ring signatures, Provable

Date: received 27 Jul 2004

Contact author: jherranz at mat upc es

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Version: 20040807:044039 (All versions of this report)

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