Security Flaws in Several Group Signatures Proposed by Popescu

In resent years, Popescu proposed several group signature schemes based on the Okamoto-Shiraishi assumption in [8-11], and claimed his schemes are secure. However, this paper demonstrates that all these schemes are insecure by identifying some security flaws. Exploiting these flaws, an attacker without any secret can mount universally forging attacks. That is, anybody (not necessarily a group member) can forge valid group signatures on arbitrary messages of his/her choice

security flaws in several group signatures proposed by popescu

Inst High Performance Comp, Univ Perugia, Univ Calgary, Univ Minnesota, Queens Univ Belfast, Soc Ind & Appl Math, IEE, OptimaNumerics Ltd, MASTER UPIn resent years, Popescu et al. proposed several group signature schemes in 8, 9, 10, 11 that based on the Okamoto-Shiraishi assumption. Their schemes are claimed to be secure. However, we identify several security flaws in their schemes and

Security Flaws in Several Group Signatures Proposed by Popescu. Cryptology ePrint archive, report 2003/207

Abstract. In resent years, Popescu proposed several group signature schemes based on the Okamoto-Shiraishi assumption in [8–11], and claimed his schemes are secure. However, this paper demonstrates that these schemes are all insecure by identifying some security flaws. Exploiting these flaws, an attacker without any secret can mount universally forging attacks. That is, anybody (not necessarily a group member) can forge valid group signatures on arbitrary messages of his/her choice