Fully Private Revocable Predicate Encryption

The authors introduce the concept of Revocable Predicate Encryption (RPE), which extends the previous PE setting with revocation support: private keys can be used to decrypt an RPE ciphertext only if they match the decryption policy (defined via attributes encoded into the ciphertext and predicates associated with private keys) and were not revoked by the time the ciphertext was created. The first challenge in RPE schemes is to preserve privacy for RPE ciphertexts, namely to ensure the attribute-hiding property, which is inherent to traditional PE constructions, and which implies the more basic property of payload hiding, used in the context of Attribute-Based Encryption (ABE).