Technical Report Number
Several credential systems have been proposed in which users can authenticate to service providers anonymously. Since anonymity can give users the license to misbehave, some variants allow the selective deanonymization (or linking) of misbehaving users upon a complaint to a trusted third party (TTP). The ability of the TTP to revoke a user's privacy at any time, however, is too strong a punishment for misbehavior. To limit the scope of deanonymization, systems have been proposed in which users are deanonymized if they authenticate ``too many times,'' such as ``double spending'' with electronic cash. While useful in some applications, it is not possible to generalize such techniques to more subjective definitions of misbehavior, e.g., it is not possible to block users who ``deface too many webpages'' on a website. We present BLAC, the first anonymous credential system in which service providers can revoke the credentials of repeatedly misbehaving users without relying on a TTP. Since revoked users remain anonymous, misbehaviors can be judged subjectively without users fearing arbitrary deanonymization by a TTP. Finally, our construction supports a $d$-strikes-out revocation policy, whereby users who have been subjectively judged to have repeatedly misbehaved at least $d$ times are revoked from the system.
Dartmouth Digital Commons Citation
Tsang, Patrick P.; Au, Man Ho; Kapadia, Apu; and Smith, Sean W., "BLAC: Revoking Repeatedly Misbehaving Anonymous Users Without Relying on TTPs" (2008). Computer Science Technical Report TR2008-635. https://digitalcommons.dartmouth.edu/cs_tr/317