Blocking Misbehaving Users in Anonymizing Networks & Broadening Nymble System
In this paper. The authors presents Nymble, a system in which servers can blacklist misbehaving users, thereby blocking users without compromising their anonymity. Their system is thus agnostic to different servers' definitions of misbehaviour servers can blacklist users for whatever reason and the privacy of blacklisted users is maintained. In pseudonymous credential systems users log into web sites using pseudonyms, which can be added to a blacklist if a user misbehaves. Anonymous credential systems employ group signatures. Basic group signatures allow servers to revoke a misbehaving user's anonymity by complaining to a group manager.