Cryptology ePrint Archive: Report 2003/194

Security Analysis of Several Group Signature Schemes

Guilin Wang

Abstract: At Eurocrypt'91, Chaum and van Heyst introduced the concept of group signature. In such a scheme, each group member is allowed to sign messages on behalf of a group anonymously. However, in case of later disputes, a designated group manager can open a group signature and identify the signer. In recent years, researchers have proposed a number of new group signature schemes and improvements with different levels of security. In this paper, we present a security analysis of five group signature schemes proposed in [25,27,18,30,10]. By using the same method, we successfully identify several universally forging attacks on these schemes. In our attacks, anyone (not necessarily a group member) can forge valid group signatures on any messages such that the forged signatures cannot be opened by the group manager. We also discuss the linkability of these schemes, and further explain why and how we find the attacks.

Category / Keywords: public-key cryptography / digital signature, group signature, forgery, cryptanalysis.

Publication Info: A compressed version of this paper appears in INDOCRYPT 2003, LNCS 2904, pp. 252-265. Springer-Verlag, 2003.

Date: received 21 Sep 2003, last revised 11 Apr 2004

Contact author: glwang at i2r a-star edu sg

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Version: 20040412:050136 (All versions of this report)

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