自认证公钥签名方案的改进

通过对张学军最近提出的高效的自认证公钥签名方案进行分析,指出了该签名方案是不安全的.因为权威机构CA也同样可以对任意消息产生自认证公钥签名,以至于验证人不能确定该签名是否是签名人所签的.同样地,签名人也完全可以否认该签名是自己签的,因为CA也能做到,因此该签名不具有不可否认性.最后,对该签名方案进行了改进,改进后的方案的安全性是基于离散对数问题的,并且效率跟原方案基本相同.同时,若在考虑预运算的情况下,改进后方案的效率比原方案稍高.

Improvement of self-certified public key signature scheme

The efficient self-certified public key signature scheme proposed by Zhang Xuejun was analyzed and the defects in security was pointed out, because Certification Authority (CA) also has the capacity of generating self-certified public key signature on any message, causing the verifier unable to make sure whether the signature is generated by the signer himself. Similarly, the signer has good reason to deny the signature, therefore, the signature losses its undeniability. Finally, based on the discrete logarithm problem, an improved signature scheme was proposed and its efficiency was the same as the former one. However, taking prior operation into consideration, the efficiency of the improved scheme was higher than the original scheme.