关键词: 代理签名, 前向安全, 伪造攻击

Abstract: Recently, some researchers have been come up with some forward secure proxy signature schemes and some improved forward secure proxy signature schemes. By analyzing the security of the three proxy signature schemes points out that they are insecure and have not characteristic of forward security. When the proxy signer’s private key is leak, the original signer can forge the proxy signature even if he don’t know the key before session. The scheme can not resist the original signer’s forgery attack.

Key words: proxy signature, forward security, forgery attack