两个指定验证人签名方案的安全性分析

Security Analysis of Two Designated-Verifier Signature Schemes

2005年,王晓明等人把多重指定验证人签名与门限代理签名结合起来,提出了一个门限代理多重指定验证人签名(Wang-Fu).同年,陈伟东等人也提出了一个指定验证人的数字签名方案(Chen-Feng-Tan).证明Wang-Fu方案中指定验证人集合的管理者可以直接伪造签名.为此,每个验证人对在验证阶段使用私钥产生的部分数据必须进行零知识证明.CFT方案不满足非传递性,即指定验证人可以向第三方证明其拥有的签名是由签名人签署的.其原因在于,该方案直接利用了Schnorr签名技巧,指定验证人很客易把拥有的签名转化为关于原始签名人公钥参数的一个普通签名.

In 2005, Wang, et al. proposed a threshold proxy multi designated-verifiers signature scheme （Wang-Fu ） by combining the properties of the threshold proxy signature and the multi designated-verifiers signature. In the same year, Chert, et al. also proposed a designated-verifier signature scheme. It is shown that the manager of the set of all verifiers can directly forge signatures, so that, each verifier should give zero knowledge proof for the partial data generated in verifying phase by using his secret key, and that CFT （Chen-Feng-Tan） scheme does not satisfy the non-transferability, i.e., the designated-verifier can prove to a third party that the signature is generated by the signer. The reason is that the scheme directly follows from the technique in Schnorr signature. The designated-verifier can easily transform the signature into a common signature with respect to the signer＇s public parameters.