Bridging the Gap in Privacy-Preserving Revocation: Practical and Scalable Revocation of Mobile EIDs

Michael Hölzl, Michael Roland, Omid Mir, René Mayrhofer

SAC '18: Proceedings of the 33rd Annual ACM Symposium on Applied Computing, 2018

Providing methods to anonymously validate the user's identity is essential in many applications of electronic identity (eID) systems. A feasible approach to realize such a privacy-preserving eID is the usage of group signature protocols or pseudonym-based signatures. However, providing a revocation mechanism that preserves privacy is often the bottleneck for the scalability of such schemes. In order to bridge this gap between practicability and privacy, we propose a scalable and efficient revocation scheme suitable for smart cards in a mobile eID architecture. By using a pseudo-random function, we derive one-time revocation tokens for the revocation check and generate proofs of validity using a new method referred to as disposable dynamic accumulators. Our scheme thereby preserves unlinkability and anonymity of the eID holder even beyond revocation and does not require online connectivity to a trusted party for the verification and revocation check.