Cryptanalysis of Zhou et al.’s proxy-protected signature schemes

Abstract: Quite recently, Zhou et al. proposed two proxy-protected signature schemes based on the RSA assumption and the hardness of integer factorization, respectively. They also provided security proofs for each signature scheme in the random oracle model. In this paper, we show that both schemes are not secure and suggest a method for fixing the security flaw. [Copyright &y& Elsevier]