Abstract: A fair contract signing protocol allows two potentially mistrusted parties to exchange their commitments to an agreed contract over the Internet in a fair way so that either each of them obtains the others signature or neither party does. The existing protocols face the problem of more number of transactions in between TTP and party. Also the time complexity and computational complexities are more. In this paper we are proposing a fair contract signing protocol based on secret sharing scheme. The proposed method satisfies property of abuse freeness and fairness. That is if the protocol is executed unsuccessfully, none of the two parties can show the validity of intermediate results to others. The proposed scheme is more reliable, secure and less complex.

Keywords: Fair-exchange protocols, digital signatures, security, privacy preserving, dynamic groups.