Ticket and Challenge-Based Protocols for Timestamping

摘要

In this paper we introduce two methods that allow you to certify the time when a particular document was presented to a certifying authority. While some of the algorithms that served this purpose already existed in the literature, our methodology has significant practical advantages. The two methods we show are more straightforward, by giving a user a chance, in some cases, to operate on one value rather than two. They give the user the flexibility to select the most appropriate algorithm. They provide for a reasonable sharing of the workload between the user and the timestamping authority.