New X.509-based mechanisms for fair anonymity management

• We extend the X.509 infrastructure to support anonymity and unlinkability revocation.
• The additional functionality is included by means of OCSP and CRL extensions.
• Also, a new protocol, Anonymous Certificate Fairness Protocol (ACFP) is proposed.
• ACFP provides an X.509-like mechanism to convey evidence proving a misbehavior.
• The work includes experimental measures obtained through a prototype of our proposal.

Privacy has become a major concern in the Internet, resulting in an increased popularity of anonymizing systems aimed to protect users' identities. However, service providers sometimes interpret this anonymity as a risk, since dishonest users may take advantage of it. A possible solution is to create a practical implementation of fairness mechanisms to reach an equilibrium between anonymity and its different types of revocation. Furthermore, in order to reach a wide acceptance, any new mechanism must be easily deployable in current systems and must be adaptable (from the functionality perspective) to the needs that may arise in different situations. To that end, we propose a set of extensions to the CRL and OCSP procedures of the X.509 infrastructure, and a new protocol for easing the task of providing evidence of illegitimate actions. On one hand, the adaptability of our scheme relies on the already widely deployed X.509 infrastructure. On the other hand, the functionality provided by our proposal is mainly built upon group signatures, which gives it a vast variety of schemes to choose from, depending on the specific needs that may arise.