Multi-party non-repudiation protocol supporting transparent offline TTP

Non-repudiation protocols are essential for realization of electronic commerce.These protocols can be classified into two categories: two-party protocols and multi-party protocols.The existing multi-party non-repudiation protocols do not support transparent TTP.To overcome this problem,a multi-party non-repudiation protocol that supports transparent TTP was presented.Its non-repudiation evidences do not require the use of TTP signature.The protocol consists of a dispute resolution policy and three sub-protocols,i.e.,the exchange sub-protocol,the cancel sub-protocol and the finish sub-protocol.In normal case,the protocol was finished by exchanging three message flows.Technical analysis shows that the protocol satisfies fairness,timeliness and confidentiality.