Ciphertext-Policy Attribute-Based Encryption for General Circuits in Cloud Computing

Driven by the development of Internet and information technology, cloud computing has been widely recognized and accepted by the public. However, with the occurrence of more and more information leakage, cloud security has also become one of the core problem of cloud computing. As one of the resolve methods of it, ciphertext-policy attribute-based encryption (CP-ABE) by embedding access policy into ciphertext can make data owner to decide which attributes can access ciphertext. It achieves ensuring data confidentiality with realizing fine-grained access control. However, the traditional access policy has some limitations. Compared with other access policies, the circuit-based access policy ABE supports more flexible access control to encrypted data. But there are still many challenges in the existing circuit-based access policy ABE, such as privacy leakage and low efficiency. Motivated by the above, a new circuit-based access policy ABE is proposed. By converting the multi output OR gates in monotonic circuit, the backtracking attacks in circuit access structure is avoided. In order to overcome the low efficiency issued by circuit conversion, outsourcing computing is adopted to Encryption/Decryption algorithms, which makes the computing overhead for data owners and users be decreased and achieve constant level. Security analysis shows that the scheme is secure under the decision bilinear Diffie-Hellman (DBDH) assumption. Numerical results show the proposed scheme has a higher computation efficiency than the other circuit-based schemes.