关键词: 私钥分发, 协议, 口令, 可分离匿名的私钥分发（SAKI）

Abstract: To solve the problems of message integrality protection and dictionary attack of password in SAKI private key issuing protocol，a new improved SAKI private key issuing protocol is presented.New protocol solves the problems of juggle message attack and dictionary attack via extending entropy of password.At the same time，it uses the master key to protect the password，prevents attacker from imitating user to get private key when the password is leaked.The security of new protocol improves remarkably.Protocol’s security is based on computational Diffie-Hellman and bilinear Diffie-Hellman assumption.

Key words: private key issuing, protocol, password, Separable and Anonymous Identity-based Key Issuing（SAKI）