Privacy Preserving Revocable Predicate Encryption Revisited
Predicate Encryption (PE) that provides both the access control of ciphertexts and the privacy of ciphertexts is a new paradigm of public-key encryption. An important application of predicate encryption is a searchable encryption system in a cloud storage, where it enables a client to securely outsource its data to an untrusted cloud server and to search over it even without revealing a keyword itself. One practical issue of predicate encryption is to devise an efficient revocation method to revoke a user when the secret key of the user is compromised. Privacy preserving Revocable Predicate Encryption (RPE) can provide not only revocation, but also the privacy of revoked users.