Directly Revocable and Verifiable Key-Policy Attribute-based Encryption for Large Universe

For practical data sharing applications, many attributebased encryption (ABE) schemes were proposed with different kinds of properties, such as supporting large universe, revocation, verification and so on. However, existing schemes seldom support these three important properties simultaneously. In this paper, we present a directly revocable and verifiable key-policy ABE scheme for large universe (DRV-KP-ABE). The new scheme supports large universe, and attributes do not need to be enumerated at stage of setup. Meanwhile, our scheme allows the trusted authority to revoke users by only updating the revocation list without interaction with non-revoked users. We use the subset difference method for revocation which greatly improves the broadcast efficiency compared with the complete subtree scheme. In addition, the proposed scheme enables the third party to update ciphertexts with public information, and the auditor assures the third party updated ciphertexts correctly. The DRV-KP-ABE scheme is selectively secure under q-type assumption in the standard model.