Much research on Internet security has concentrated on generic mechanisms such as firewalls, IP authentication and protocols for large scale key distribution. However, once we start to look at specific applications, some quite different requirements appear. We set out to build an infrastructure that would support the reliable electronic distribution of books on which doctors depend when making diagnostic and treatment decisions, such as care protocols, drug formularies and government notices. The integrity, authenticity and timeliness of this information is important for both safety and medico-legal purposes. We initially tried to implement a signature hierarchy based on X.509 but found that this had a number of shortcomings.

We therefore developed an alternative means of managing trust in electronic publishing. This has a number of advantages which may commend it in other applications. It does not use export-controlled cryptography; it uses much less computation than digital signature mechanisms; and it provides a number of features that may be useful in environments where we are worried about liability. We also present our intermediate solution - the first ever large scale deployment of one-time signature systems. The move to one-time signatures enabled considerable simplification, cost reduction and performance improvement. We believe that similar mechanisms may be appropriate for protecting other information that changes slowly and remains available over long time periods. Book and journal publishing in general appear to be strong candidates.