Attribute Based Hybrid Encryption with Verifiable Delegation in Cloud Computing Using Circuit Ciphertext-Policy

Abstract

In the cloud, for achieving access control and keeping data confidential, the data owners could adopt attribute-predicated encryption to encrypt the stored data. Users with inhibited computing power are however more liable to delegate the mask of the decryption task to the cloud servers to reduce the computing cost. As a result, attribute-predicated encryption with delegation emerges. Still, there are caveats and questions remaining in the precedent germane works. For instance, during the delegation, the cloud servers could tamper or supersede the delegated ciphertext and respond a forged computing result with malignant intent. They may withal cheat the eligible users by responding them that they are ineligible for the purport of cost preserving. Furthermore, during the encryption, the access policies may not be flexible enough as well. Since policy for general circuits enables to achieve the most vigorous form of access control, a construction for realising circuit ciphertext-policy attribute-predicated hybrid encryption with verifiable delegation has been considered in our work. In such a system, coalesced with verifiable computation and encrypt-then-mac mechanism, the data confidentiality, the fine-grained access control and the correctness of the delegated computing results are well ensured concurrently. Besides, our scheme achieves security against culled-plaintext attacks under the k-multilinear Decisional Diffie-Hellman postulation. Moreover, an extensive simulation campaign corroborates the feasibility and efficiency of the proposed solution.