Enhanced Outsider-anonymous Broadcast Encryption with Subset Difference Revocation

This paper puts forward an efficient broadcast encryption in public key setting employing ternary tree subset difference method for revocation. It provides outsider anonymity disabling the revoked users from getting any information of message and concealing the set of subscribed users from the revoked users. Our approach utilizes composite order bilinear group setting and exhibits significant improvement in the broadcast efficiency. The proposed scheme compares favourably over the existing similar schemes in standard model. The public key and secret key sizes are poly-logarithmic while the ciphertext size is sublinear in total number of users. Our scheme achieves selective security against chosen plaintext attack in the standard model under reasonable assumptions.