Arne Ansper, Ahto Buldas, Märt Saarepera, and Jan Willemson. Improving
the Availability of Time-stamping Services. In Vijay Varadharajan and Yi
Mu, editors, The 6th Australasian Conference on Information Security
and Privacy, volume 2119 of Lecture Notes in Computer
Science, pages 360--375, Sydney, Australia, 11--13 July 2001.
Springer-Verlag. ISBN 3-540-42300-1. [pdf (239K),
ps.gz (75K), ps.bz2
We discuss the availability questions that arise when digital time stamps are used for preserving the evidentiary value of electronic documents. We analyze the time-stamping protocols known to date and point out some weaknesses that have not been addressed so far in scientific literature. Without addressing and solving them, any advantage of the linkage-based protocols over the hash-and-sign time-stamping would be questionable. We present several new techniques and protocols for improving the availability of both the hash-and-sign and the linkage-based time-stamping services. We introduce fault-tolerant linking as a new concept to neutralize fault-sensitivity as the main weakness of linkage-based time-stamping.
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