Probable Security Proof of A Blind Signature Scheme over Braid Groups

In this paper, we reinvestigate the security analysis of blind signature scheme over braid groups proposed by Verma in 2008. A blind signature scheme is a cryptographic primitive used for e-commerce for getting a signature from the signer without revealing any information about its contents. These schemes are especially used in e-transactions, e-votings, DRM systems, etc. The security of blind signature is basically defined by two properties blindness and unforgeability. Here we prove a special form of unforgeability called one more forgery defined by Pointcheval et al. Although, Verma has defined the same and discussed the security analysis using a stronger assumption called chosen target conjugator search problem. In this paper, we also discuss the analysis using a simple problem, which is much closer to conjugate search problem.