Reducing Revocation Lists in CS-Based Revocable Group Signature Scheme Using Vector Commitment

In the current ID-based user authentication systems, the user's personal use history can be traced, because the user's ID can be linked. Therefore, this may cause privacy issues. As a solution, group signatures have been researched to realize the anonymous authentication. The group signature requires a revocation function to revoke signatures generated by a user who leaves or is removed from a group. An efficient revocable group signature scheme using a tree structure called the Complete Subtree (CS) method has been proposed. However, the size of the revocation list depends on the number of revoked users. In this paper, we propose an extended scheme where the size of revocation list is reduced, by compressing a number of entries in the list by a vector commitment. We implement the proposed scheme on a PC, and evaluate the effectiveness.