Private authentication

Abstract

Frequently, communication between two principals reveals their identities and presence to third parties. These privacy breaches can occur even if security protocols are in use; indeed, they may even be caused by security protocols. However, with some care, security protocols can provide authentication for principals that wish to communicate while protecting them from monitoring by third parties. This paper discusses the problem of private authentication and presents two protocols for private authentication of mobile principals. In particular, our protocols allow two mobile principals to communicate when they meet at a location if they wish to do so, without the danger of tracking by third parties. The protocols do not make the (dubious) assumption that the principals share a long-term secret or that they get help from an infrastructure of ubiquitous on-line authorities.