Secured Authorized Data Using Hybrid Encryption in Cloud Computing

Abstract

In today's world to provide a security to a public network like a cloud network is become a toughest task however more likely to reduce the cost at the time of providing security using cryptographic technique to delegate the mask of the decryption task to the cloud servers to reduce the computing cost. As a result, attributebased encryption with delegation emerges. Still, there are caveats and questions remaining in the previous relevant works. For to solution to all problems the cloud servers could tamper or replace the delegated cipher text and respond a forged computing result with malicious intent. They may also cheat the eligible users by responding them that they are ineligible for the purpose of cost saving. Furthermore, during the encryption, the access policies may not be flexible enough as well. Since policy for general circuits enables to achieve the strongest form of access control, a construction for realizing circuit cipher text-policy attribute-based hybrid encryption with verifiable delegation has been considered in our work. In such a system, combined 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 guaranteed at the same time. Besides, our scheme achieves security against chosen-plaintext attacks under the k-multilinear Decisional Diffie-Hellman assumption. Moreover, an extensive simulation campaign confirms the feasibility and efficiency of the proposed solution. There are two complementary forms of attribute-based encryption. One is key-policy attribute-based encryption (KP-ABE) [8], [9], [10], and the other is cipher text-policy attribute-based encryption. In a KP-ABE system, the decision of access policy is made by the key distributor instead of the enciphered, which limits the practicability and usability for the system in practical applicationsthe access policy for general circuits could be regarded as the strongest form of the policy expression that circuits can express any program of fixed running time.