The Privacy Strategy In Cloud Computing Based On User Trust Hierarchy

In recent years,with the rapid development of the Internet,Cloud computing gradually become the trend and direction of the development of today’s computer.However,there are many factors restrict the devolopment of cloud computing in spite of the significant advantages,the most important factor of these is privacy safety problem.But if we do the unified treatment for all users,it will increase the work load of cloud server and lead to the efficiency of cloud computing should be reduced substantially.So under this application background the paper propose a new privacy strategy which base on the user trust hierarchy under this background which is giving different users different privacy solutions by dividing users into different trust level. In order to achieve this goal, we define a trusted third party as the access control layer and this third party is responsible for storing user information and cloud service providers information as well as playing the role of secret key management center. Each server request from user to cloud service provider will send to the third party firstly,by parsing the request data packets the third party will chose different data process method then send the processed data to corresponding cloud service provider enventually.This paper focus on the level III and level IV detail solution which data process work is taking by the trusted third party.In level III solution we use the improved AES encreption which diffusion performance is improved as the core algorithm. We find a proper Hadamard matrix to replace the original Circular matrix in Mix Column phase. Besides we verify the security by analysis mainly attacks that it faced.In level IV solution we choose the improved fully homomorphic encreption over integer which encrept and decrept performance is improved as the core algorithm. We use Chinese Remainder Theorem to find the proper Congruence group to encrept a number of plaintext bit. Besides that we verify semantic security of improved encreption algorithm.At last we give both improved algorithm tests which is the comparision paramenter of encreption cost, decreption cost and so on which can prove the application feasibility in this strategy.