Efficient User Revocation for Privacy-aware PKI

Privacy-aware Public Key Infrastructure (PKI) can maintain user access control and yet protect user privacy, which is envisioned as a promising technique in many emerging applications. To justify the applicability of privacy-aware PKI and optimize the performance, it is highly important to ensure the efficiency of handling user revocations. In practice, user revocation can be due to various predictable and unpredictable reasons, e.g., subscription expiration, network access policy violation, group changing, secret key exposure, etc. Both predictable and unpredictable reasons can happen concurrently, which makes the design of efficient user revocation mechanism challenging. In this paper, we study how to achieve optimized user revocation cost with respect to various revocation approaches. We also propose an advanced scheme Delta-RL that ensures an optimized overall performance in terms of communication, computation and storage, as justified by the extensive analysis.