An Efficient And Dynamic Ciphertext Search Method For Cloud Storage

Cloud storage has the advantages of high scalability, inexpensive, extensive access and eases management of remote data repository, which can make a number of enterprises and users to get rid of the construction and maintenance of storage systems, and greatly reduce the user’s storage costs. Hence it has broad market application prospects. However, there are many serious security problems in existing cloud storage services. Many potential cloud storage users will turn to the traditional storage systems due to the fear of data leakage in cloud storage services. It has largely hindered the promotion of cloud storage services. Therefore, how to design a safe and efficient storage system becomes an important research topic in the field of cloud storage.In order to solve the security issues of cloud storage, we design a dynamic ciphertext search method for cloud storage. With Goh’s security index, we encrypt the files and the file-keyword index before upload,in this way we can ensure that the server cannot get valid information from it. Then the server can seek the related files by using the search token which was generated by the client.In addition, cloud storage server may forge and tamper the search results. In order to verify the correctness of the results, we design a dynamic search authentication algorithm. The algorithm is based on the Merkle’s hash tree structure. The client generates authenticator using the file-keyword index and stores the value of root node as state. For a search, cloud storage server generates the corresponding proof after search operation, then the client can verify the search results using the proof and the search results.Finally, we designed a ciphertext search and authentication model system based on these two algorithms above. The system simulates the behavior of the cloud storage users and servers. Then we evaluated the algorithms through the system performance. The experimental results show that the system is able to ensure the confidentiality of information and verifiability of search behavior, and has a good performance in time and space, and therefore has a very important theoretical research and practical application value.