| With the increasing development of the Internet, electronic transactions have become more and more common. Fair data exchange is crucial to many applications. Especially for transferring the important data over the open and insecure networks, it needs a series of secure services to guarantee the data exchanged in a security manner. Non-repudiation is one of the important security services. By producing the irrefutable electronic evidence, it can provide the protection for valuable electronic data against false denial of their transmission or reception. So the participating parties must be responsible for their behaviors, and the denial disputes which may arise in the non-face-to-face electronic transaction are avoided. Therefore designing the security protocols for the electronic data exchanged fairly and safely is become a research hotspot. We call the security protocols which are designed to support security service of non-repudiation are the non-repudiation protocols. No doubt well-designed non-repudiation protocols will promote the further development of the electronic commerce.Under such an application background, this paper mainly presents some research results of non-repudiation protocols and their applications. The research background, the research significance and the on-going research are introduced in details. The basic concepts and the common terminologies on the non-repudiation protocols are defined. The security weaknesses and the new security requirements of the open published non-repudiation protocols are analyzed and generalized. At the same time three distinct two/multi-party protocols which can meet different security requirements have been brought forward. And their respective security is in-depth discussed and analyzed.The main contributions of this paper are as follows:1. A detailed classification of the non-repudiation protocols is given for the first time. And an accurate definition of the non-repudiation protocols is given.2. Observing the security weaknesses that exist in the open published non-repudiation protocols and utilizing public-key cryptographic system, private key cryptographic system, secure Hash function and public-key certificate,a new protocol which can prevent each participant from repudiating and cheating is put forward. Using a formal analysis tool proposed by Zhou and Qing, it is proved that the new protocol realizes the effectiveness, origin/receipt non-repudiation, strong fairness and timeliness.3. Based on the GPS digital signature scheme (presented by M Girault, G Poupard and J Stern, abbreviated as GPS scheme) and the group encryption scheme, an optimistic multi-party non-repudiation protocol with the transparent trusted third party (abbreviated as TTP) is brought forward. The offline-TTP can generate the same evidences, in case of disputes, as what the participants produced in a faultless protocol execution. This prevents people from guessing the reason that TTP involves the protocol, and avoids the bad publicity for the participants. And the protocol realize the true fairness and the expected delivery. So the protocol is of great practical value in El-commerce.4. The relationships (difference and similarity) between the non-repudiation protocols and fair exchange protocols are firstly analyzed.5. Based on publicly verifiable secret sharing scheme and group encryption scheme, a new multi-party fair exchange protocol with an off-line semi-Trusted Third Party(off-STTP) is presented, and the protocol can provide the non-repudiation services for all participants. The new protocol has the following natures: the off-STTP who needn't to be completely trusted intervenes into the exchange in case of trouble. That the Off-STTP only can decipher a sub-secret key makes sure the confidentiality of exchanged data. The participants can barter with others at their will, and the exchange topology is unknown to others including the off-STTP. So it successfully solves the open problem, i.e. the privacy of the exchange topology.6. Other problems which affect...
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