对“一个可变换限制验证人签名协议”的评论(英文)

Comment on "A Convertible Limited Verifier Signature Scheme"

在WAI M2005会议上,J.Zhang等提出一个可变换限制验证人签名协议。他们认为,这个协议的安全性建立在CDH假设和哈希函数求逆的困难性上,说“据我们所知,这似乎是第一个不依靠随机问答模型的可证明安全的可变换限制验证人签名协议”。然而,在评论时发现,实际情况恰好相反,因为他们的证明建立在许多严重逻辑错误之上。

In WAIM 2005, J. Zhang et al. proposed a convertible limited verifier signature scheme. They said that the security of this scheme is based on the CDH assumption and the difficulty of solving inverse of hash function. Furthermore, they claimed that ＂To the best of my knowledge, it seems to be the first provably secure convertible limited verifier signature scheme without using random oracle model＂. However, in this comment, we find that it is indeed just in opposition, since their proofs are established on several fatal logic errors.