Research And Realization Of Traceable Source Of Time In Digital Time-Stamping System

The technology of digital time-stamping(DTS) service is to make the traditional time-stamping digitize with computer technology.It is one kind of credible time service provided by the third party(Time-Stamping Service,TSS).The digital time-stamping data obtained from the third party can be used to prove that the data has already existed at certain time. With the development of the computer technology and INTERNET, the time-stamping technology is popularly used in digital signature, electronic commerce and so on.In recent yeas, it grows rapidly of the application of digital certificate.Many TSS is established, at the same time, the law about the digital certificate has passed. The primarily drawback existing in TSS of domestic is listed as follows: time of the digital time-stamping service primarily relies on the GPS; it has no monitoring system and backup system.Because of these drawback,it can't be to guarantee the authority and exactitude of digital time-stamping.According to the fact of DTS, this dissertation presents one blue print of traceable source of time in digital time-stamping system,which has characteristics as follows:multicenter, high reliability and monitorable and so on.In this blue print,the traceable source of time is provided through the main clock signal of NTSC so that to guarantee the authority of time-stamping;multitechnologies of time synchronization is used to make sure the reliability and exactitude of the time of digital time-stamping. One way of realization of high precision time-stamping is also presented in this dissertation.Testing indicate that the precision of time-stamping is better than 0.5us. Besides, in this dissertation, the research work as follows has been done: the technology of time synchronization, technology of embedded system based on ARM,NTP ,telephone time service .The sample of traceable source of time in digital time-stamping system is designed and realized.Testing for function and performance of the sample indicate that the blue print has characteristics as follows:multichannel time source redundancy, high reliability and monitorable,which satisfies the requirements of safety digital time-stamping.