改进的公开验证认证加密方案

Improvement of Publicly Verifiable Authenticated Encryption Scheme

现有的认证加密方案中,如果签名者否认签名,接收者不能向其它任何验证者证实签名者的诚实性。为了解决此问题,Ma Chen提出了一个有效的公开验证认证加密方案。而文中证明了他们的方案不能抵制基于单向Hash函数的特殊攻击,即不诚实的接收者对任何消息都可成功地伪造签名者的签名;然后在只基于求解离散对数难题和对消息增加冗余度的基础上,提出了一种改进方案。改进方案不仅具有不可伪造性、不可否认性和机密性等特点,而且在计算复杂性等方面优于Ma Chen方案。

In the most present authenticated encryption schemes the recipient cannot prove the signer's dishonesty to any verifier if the signer denies the signature. To overcome this problem, Ma-Chen proposed an efficient authenticated encryption scheme with public verifiability. In this paper it was demonstrated that their scheme cannot resist the special forgery attack about the one-way Hash function, i.e., a dishonest recipient can easily forge valid signatures for any messages on behalf of the signer. To solve the above weakness, based on the Discrete Logarithm Problem, a secure improved scheme was proposed. This scheme can satisfy all the desired security requirements. Further, the proposed scheme is more efficient than Ma-Chen's in terms of the computation cost.