Abstract:

A new efficient group signature scheme proposed by J.H.Zhang et al is analyzed. We point out its shortages in the module and prove that this scheme can be attacked completely in the same module algorithm. We present its improved scheme on RSA and discrete logarithm assumption, which contains the merits of the original scheme, unforgeability and anonymity, and gets rid of the original shortages. The total computation of signature and verification take only 6 exponents and the efficiency raised by nearly two times in the improved scheme.

Key words: digital signature, group signature, security analysis, discrete logarithm