关键词: 数字签名, 代理签名, 公钥替换攻击, 可证明安全

Abstract: In this paper, a new proxy signature scheme proposed by Lu Rong-bo et al. is given a detailed cryptanalysis. This paper points out that this scheme is not secure against public key substitution attack and proposes a method to attack the new scheme. Based on this, one improved scheme is given and concluded that it is not only secure against the original signer’s forgery attack effectively but also avoiding the problems of the original scheme. Compared with the original scheme, the new scheme is more security and has the same computation complexity.

Key words: digital signature, proxy signature, public key substitution attack, provable security