Computationally Efficient Ciphertext-Policy Attribute-Based Encryption with Constant-Size Ciphertexts

Ciphertext-policy attribute-based encryption (CP-ABE) is extremely suitable for cloud computing environment in that it enables data owners to make and enforce access policies themselves. However, most of the existing CP-ABE schemes suffer severe efficiency drawbacks due to large computation cost and ciphertext size, both of which linearly increase with the complexity of access policies. Aiming at tackling the challenge above, in this paper, we propose a CP-ABE scheme which features constant computation cost and constant-size ciphertexts. The proposed CP-ABE scheme is proven selective-secure in the random oracle model under the decision n-Bilinear Diffie-Hellman Exponent (n-BDHE) assumption, where n represents the total number of attributes in universe. In particular, the proposed scheme can efficiently support AND-gate access policies with multiple attribute values and wildcards. Performance comparisons indicate that the proposed CP-ABE scheme is promising in real-world applications, especially for the scenarios where computation and bandwidth issues are major concerns.