Communication-efficient revocable identity-based signature from multilinear maps

An efficient revocation mechanism is absolutely necessary for a cryptosystem with a large number of users to strengthen the system security. Besides the integrity and authentication of messages, a revocable identity-based signature scheme also provides a public way to remove those users whose credentials are expired or whose private keys are compromised from the system. In the existing revocable identity-based signature schemes, the workload of the authority performing the revocation procedure is linear or logarithmic in the number of non-revoked users, which decrease its usability in many practical scenarios (e.g., ad hoc networks) that are sensitive of bandwidth. In this study, we propose the first revocable identity-based signature scheme with constant sizes of private key, update key and signature by using multilinear maps. The security of the proposed scheme is proven in the selective-revocation list and adaptive-message setting, without random oracles. Performance discussions show that our scheme owns advantages in terms of functionality and efficiency.