Cryptology ePrint Archive: Report 2004/290

The Security of the FDH Variant of Chaum's Undeniable Signature Scheme

Wakaha Ogata and Kaoru Kurosawa and Swee-Huay Heng

Abstract: In this paper, we first introduce a new kind of adversarial goal called {\em forge-and-impersonate} in undeniable signature schemes. Note that forgeability does not necessarily imply impersonation ability. We then classify the security of the FDH variant of Chaum's undeniable signature scheme according to three dimensions, the goal of adversaries, the attacks and the ZK level of confirmation and disavowal protocols. We finally relate each security to some well-known computational problem. In particular, we prove that the security of the FDH variant of Chaum's scheme with NIZK confirmation and disavowal protocols is equivalent to the CDH problem, as opposed to the GDH problem as claimed by Okamoto and Pointcheval.

Category / Keywords: public-key cryptography / Undeniable signature, security analysis

Publication Info: The proceedings version of this paper will be presented at PKC 2005

Date: received 5 Nov 2004, last revised 25 Feb 2005

Contact author: shheng at mmu edu my

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Version: 20050225:072326 (All versions of this report)

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