Abstract: As existing ID-based signature scheme needs to trust Private Key Generator（PKG） unconditionally，PKG can compute the private key of any user and forge a signature of any one in scheme.So an ID-based signature scheme without trusted PKG is proposed.In the scheme，the private key is generated by PKG and users，which can stop PKG forging signature.The scheme also has the merits of verifiability，unforgeability and undeniability，and only the designated receiver can verify the validity of the signature.

Key words: ID-based, private key generator, cryptography

摘要： 由于现有的基于身份的签密方案中，所有用户的私钥都由无条件信任私钥中心（PKG）产生，因此不诚实的PKG就可以伪造任意用户的签名。基于此，提出了一个基于身份的无需可信中心的签密方案，该方案中签密密钥由PKG和用户共同产生，可防止PKG的伪造行为，方案具有可验证性、不可伪造性和不可否认性，并且只有指定的接收者才能验证签密的正确性。

关键词: 基于身份, 私钥产生中心, 签密