Enhanced securely fair non-repudiation protocol

Non-repudiation and fairness are two important issues in electronic transactions. There is a famous securely fair non-repudiation protocol (SFNRP) proposed by B. Meng that can satisfy these two requirements. However, the bottleneck problem does not be solved completely. In this paper, we propose a new fair non-repudiation protocol, in which the trusted third party (TTP) is off-line to further reduce TTP´s involvement and solve the bottleneck problem. By security analyses, the new protocol can greatly improves SFNRP. At the same time, it can provide the protocol privacy and reduce the involvement of TTP.