Distributed timestamping with smart cards using efficient overlay routing
Guenther Starnberger, Lorenz Froihofer, Karl Michael Goeschka · 2010
A secure digital timestamp can assert the existence of a particular document at a specific point in time. While centralized timestamp servers show dependability draw-backs with respect to node or link failures, e.g., outages of the Internet connectivity, distributed timestamping pro-tocols don’t have these drawbacks, but are nowadays rarely seen in practice because of the distributed trust require-ments and applicability issues. In this paper, we contribute with: (i) A distributed time-stamp protocol addressing practical applicability issues with an efficient overlay routing architecture able to mini-mize the effects of node churn and connection establishment delays, at the cost of higher impacts of hop-to-hop latencies, (ii) Smart card integration to introduce a distributed web of trust and hence increase the security of applied timestamps, and (iii) An evaluation using a prototype implementation and network simulation that shows the performance gains of our protocol in comparison to the state-of-the-art. The properties of our protocol allow for its application in scenarios where distributed timestamping protocols have not been an option so far, for example, because of mutually distrusting users. Furthermore, while many existing dis-tributed timestamping protocols are only theoretically eval-uated, we show the feasibility of our protocol with a proto-type implementation. 1.