Certificate recommendations to improve the robustness of web of trust

Abstract

Users in a distributed system establish webs of trust by issuing and exchanging certificates amont themselves. This approach does not require a central, trusted keyserver. The distributed web of trust, however, is susceptible to attack by malicious users, who may issue false certificates. In this work, we propose a method for generating certificate recommendations. These recommendations guide the users in creating webs of trust that are highly robust to attacks. To accomplish this we propose a heuristic method of graph augmentation for the certificate graph, and show experimentally that it is close to optimal. We also investigate the impact of user preferences and non-compliance with these recommendations, and demonstrate that our method helps identify malicious users if there are any. Keywords: Authentication, certificates, PGP keyrings, graph connectivity. © Springer-Verlag 2004.