An expressive and provably secure Ciphertext-Policy Attribute-Based Encryption

Ciphertext-Policy Attribute-Based Encryption (CP-ABE) allows to encrypt data under an access policy, specified as a logical combination of attributes. Such ciphertexts can be decrypted by anyone with a set of attributes that satisfy the access policy. We propose a Ciphertext-Policy Attribute-Based Encryption, which is based on a recent secret sharing method called Linear Integer Secret Sharing Scheme (LISS). In this scheme, the encryptor can specify the access policy in terms of LISS matrix M, over the attributes in the system. The scheme is selectively secure under Decisional Bilinear Diffie-Hellman (DBDH) assumption.