Authenticating the source of a message in a large
distributed system can be difficult due to the lack of a single
authority that can tell for whom a channel speaks. This has led many
to propose the use of a path of authorities, each able to authenticate
the next, such that the first authority in the path can be
authenticated by the message recipient and the last authority in the
path can authenticate the message source. In this talk we suggest the
use of multiple such paths to bolster assurance in the authentication
of the message source, and explore properties of those paths that
strengthen authentication. We demonstrate this approach with
PathServer, a web-based service for locating paths from a trusted key
to a query key in the PGP framework. We describe the challenges in
building PathServer, experience with its usage, and ongoing work.
- Michael Reiter and Stuart Stubblebine
- Affiliation: AT&T Laboratories
For more information, see http://www.research.att.com/~reiter/PathServer.