Efficient and Provable Secure Ciphertext-Policy Attribute-Based Encryption Schemes

Abstract

With a Ciphertext-Policy Attribute-Based Encryption (CP-ABE) scheme, a user’s private key is associated with a set of attributes and the data is encrypted under an access policy defined by the message sender. A user can decrypt a ciphertext if and only if her attributes satisfy the access policy. In CP-ABE, since the message sender enforces the access policy during the encryption phase, the policy moves with the encrypted data. In this paper, we provide an efficient CP-ABE scheme which can express any access policy represented by a formula involving the and (∧) and or (∨) operators. The scheme is secure under Decision Bilinear Diffie-Hellman (DBDH) assumption. Furthermore, we extend the expressiveness of the scheme by including the of operator in addition to ∧ and ∨. We provide a comparison with some existing CP-ABE schemes and show that our schemes are more efficient.