Mediator-Based Immediate Attribute Revocation Mechanism for CP-ABE in Multicast Group Communications

Attribute Based Encryption (ABE) scheme is a mechanism that allows implementing cryptographic fine grained access control to shared information. It achieves information sharing of type one-to-many users, without considering the number of users and their identities. However, original ABE systems presents some drawbacks, especially the non-efficiency of their attribute/key revocation mechanisms.Based on Ciphertext-Policy ABE (CP-ABE) scheme, we propose an efficient proxy-based immediate private key update for multicast group communications. Our solution does require neither re-encrypting cipher-texts, nor affecting other users (Updating secret keys).The proxy that has been introduced plays the role of a necessary semi-trusted assistant during the decryption process without taking decisions about who is eligible or not to decrypt data.Finally, we demonstrate that our scheme guarantees security requirements that we target and we also show through analysis that our scheme achieves effectively its goals.