The Research And Implementation Of Email Non-repudiation

The propose of non-repudiation services is to produce,collect,maintain a evidence of event and action that is being announced, And make this evidence obtainable and can be affirm,so we can use this service to solve the dispute of a event that is occur or not.The non-repudiation services is used to find out responsibility and audit after event.The services can be classified the origin of non-repudiation and the receipt of non-repudiation.The non-repudiation of email can have the evidence to prove the real sender and receiver.For this reason,the non-repudiation services can resolve usual problems about e-mail security such as fake,deny,hostility mail and spam.So,the research of the email non-repudiation has an important in meaning theory and value of utilities. This thesis summarizes the research as follows: 1. Analyzing the current research situations of email non-repudiation, including the existent problems. Much research work has been done in at home and abroad.The research work can be divided mainly into two ways: The non-repudiation of origin uses signature technology.The non-repudiation of origin and receipt uses the non-repudiation protocol. Currently,non-repudiation protocol has some drawbacks.First,it needs more than five data communications in one secure message communication,TTP((Third Trust Party)) is the bottleneck of the performance for many data communications.The protocol security has a more degree of dependence on the TTP.It is difficult for the implementation of the the TTP. PGP and S/MIME are the representative technology of non-repudiation of origin.But there are some drawbacks: First, It can not force the sender carry -VII-广西师范大学硕士学位论文out the responsibility of non-repudiation.Second, MTA(Message Transfer Agent) not authenticating the id of the sender UA(User Agent),it can waste the resource of MTA. 2. Thesis propose a double-encrypted key non-repudiation protocol, Aiming at the existing problems of non-repudiation protocol. This thesis gives prove the correctness by a formal analysis on the proposed protocol, The proposed protocol can provide the non-repudiation for sender and receiver. The security of this protocol bases on the security of cryptography algorithms, It has the following advantages: (1) The proposed protocol guarantees the confidentiality because of the encrypted protocol messages. (2) It needs only four data communications in one secure message communication.(3) TTP is not the bottleneck of the performance for only involved two data communications. So,the proposed protocol is easily applied in the implementation. 3.The thesis propose MTA non-repudiation method by using DNS hierarchy CA(Certificate Authority),aiming at the current existing drawbacks on the origin of non- repudiation. According to the MTA non-repudiation method, we give an implementation on MTA software. We put forward a certificate trust model based on DNS hierarchy and certificate verify algorithm in the proposed protocol. The proposed certificates verify algorithm does not need the CA online. We have done a great deal of online experiments.The analysis and conclusion of the experiment data indicate that "MTA non-repudiation method by using DNS hierarchy CA (Certificate Authority)"is good for research and viable for design and correct for implementation Finally, the thesis summarizes the contribution of the research and puts forward a plan of the future work.