Hierarchical Time-Stamp Protocol: Acquiring Reliable Time-stamp from Local Time Stamping Server

Time Stamp Protocol (TSP) is a basic security component in e-world, and Time Stamping Server (TSS)as a Trusted Third Party (TTP) generally is implemented on Internet other than in LAN. The acquiring reliability of the existing time-stamp protocols has been mainly focused by researchers in recent years, but the time delay problem produced by frequent time-stamp request has not been paid enough attention to yet. However, simply putting the TSS into LAN may deteriorate its reliability.To solve this problem, a novel Hierarchical Time-Stamp Protocol (HTSP) is proposed in this paper which enables making reliable time stamp in LAN. The hierarchy model in HTSP contains two TSS: Internet TSS and local TSS.Therefore, the advantage of a quick time stamp response of the local TSS is used, whereas the disadvantage of a possible time stamp fake in the local TSS could be overcome by periodically acquiring time stamp from the Internet TSS. The security analysis shows that reliability of time stamp in the HTSP is still remaining unchanged in comparison with the current TSP.