| Summary: | 碩士 === 國立高雄第一科技大學 === 電腦與通訊工程系 === 89 === In internet society, to prove the ownership of the document is very important since electronic document can not be signed by hand. We must add TSA (Time Stamp Authentication) for a docment to prove the ownership. TSA usually be provided by a trusted third party. When a dispute about the ownership of the document, to decide the ownership of the document by the time which in the time stamp. In this thesis, we implement a TSA server by RSA and MD5. It accepts the request to produce the TSA of a document. The TSA server must get a time for TSA. The time is used to decide the ownership of the document. Therefore, it must be trust. And it can’t be falsified or forged. In our implementation, TSA server does not use the time of local system. It get the time from NTP (Network Time Protocol) server. At present, the secure of NTP server depends on MD5/DES technique. But they was inconvenient in key exchange. In this thesis, we use both RSA and MD5 to provide high secure of time source and cope with the key exchange problem. To divide time source and NTP server to the different party, to falsify the system time of TSA server will not affect the TSA. It is secure to get time and produce TSA by the such skeleton.
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