Unbounded Revocable Decentralized Multi-Authority Attribute-Based Encryption Supporting Non-monotone Access Structures

Ciphertext-policy attribute-based encryption (CP-ABE) is a cryptographic technology that enforces an access control mechanism over encrypted data by specifying an access policy with encrypted data and introducing an attribute authority (AA) that manages user’s attributes. A CP-ABE with multiple attribute authorities and no central authority, a decentralized multi-authority CP-ABE (DMA-CP-ABE), can achieve more realistic attribute management than CP-ABE with a single authority. However, DMA-CP-ABE has an attribute revocation problem. As a different problem, the size of the public parameters of each AA is proportional to the size of the attribute universe managed by each AA. Moreover, since most existing DMA-CP-ABE schemes support only monotonic access structures, the size of the access policy specified in the ciphertext becomes large when an encryptor specifies a non-monotonic access policy in the ciphertext. Therefore, the DMA-CP-ABE that supports the attribute revocation, constant-size public and secret parameters (a.k.a unboundedness), and non-monotonic access structure is required. However, to the best of our knowledge, no one has proposed it yet. In this paper, we propose a new unbounded revocable DMA-CP-ABE (UR-DMA-CP-ABE) that supports a non-monotone access structure. We prove that our scheme achieves adaptively payload-hiding against chosen-plaintext attacks under the decisional linear (DLIN) assumption.