A privacy-preserving multi-keyword ranked retrieval scheme in cloud computing

Big data and cloud computing could bring security problems. In order to ensure data security and user privacy, people would choose to store data in the cloud with ciphertext. How to search data efficiently and comprehensively without decryption has become the focus of this paper. In this paper, we propose an efficient privacy protection scheme. In this scheme, Elliptic Curve Cryptography (ECC) is adopted to encrypt the data. It can reduce the computing cost of encryption and decryption uploading the encrypted files and indexes to the cloud server. Then it can authorize users to generate trap door using hash conflict function, and send it to Cloud Service Provider (CSP) for searching for matched ciphertext. The CSP uses the Apriori algorithm to extend keywords and search index to match the ciphertext. In this paper, we will use the Apriori algorithm to extend the keywords' semantics, match the index list based on these keywords, and return the requested file-set which is more consistent with the user's search. Experiments show that compared with traditional methods, files can be encrypted, decrypted, and recovered more quickly when we use this method. It can also ensure the privacy of data and reduce the communication overhead.