基于离散对数的有向签名方案及其应用

有向签名方案要求签名的验证必须得到接收者或签名者的合作，其目的是为了保护接收者的隐私，本文提出一个基于离散对数的有向签名方案，该方案中伪造签名的困难性等价于伪造ELGamal签名，基于该有向签名方案设计了一个带有离线半可信第三方的公平交换协议。

Directed signature scheme based on discrete logarithms and its application

Directed signature schemes, introduced by Lim and Lee, have the property that the signature can be verified only with the help of the signature receiver or of the signer. Such signature schemes are intended to protect the privacy of the signature receiver in applications where the signed message contains information personally sensitive to the receiver. In this paper, a directed signature scheme based on discrete logarithms is presented. Forging signatures in the proposed scheme is equivalent to forging ElGamal signatures. Finally, based on the proposed directed signature scheme, a fair exchenage protocol with an off line semi trusted third party is proposed.