A multi-party non-repudiation protocol with semi-trusted third party

Multi-party exchange protocols are so widely used in electronic commerce that more and more attention is being paid to designing multi-party protocols or algorithms. Multi-party protocols with non-repudiation play an important role in data fair exchange in the Internet. In this paper, we present a new multi-party protocol with off-line semi-trusted third party (STTP). The protocol is very efficient, at most 5|R|message are broadcast.