Cryptology ePrint Archive: Report 2003/129

Attack on Han et al.'s ID-based Confirmer (Undeniable) Signature at ACM-EC'03

Fangguo Zhang and Reihaneh Safavi-Naini and Willy Susilo

Abstract: At the fourth ACM conference on electronic commerce (EC'03), S. Han, K.Y. Yeung and J. Wang proposed an ID-based confirmer signature scheme using pairings (actually, this is an ID-based undeniable signature scheme). However, in this paper, we will show that this signature scheme is not secure. The signer can deny any signature, even this signature is his valid signature and any one can forge a valid confirmer signature of a signer with identity ID on an arbitrary message and confirm this signature to the verifier.

Category / Keywords: Confirmer signature, Undeniable signature, Attack, Bilinear pairings, ID-based cryptography.

Date: received 29 Jun 2003, last revised 11 Aug 2003

Contact author: fangguo at uow edu au

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Version: 20030812:022254 (All versions of this report)

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