A Secure Conjunctive Keyword Search Using a Hierarchical Bloom Filter

In recent years, remote storage services are rapidly spreading in cloud computing. In such a system, there is often a case where a client who makes use of a cloud service wants to protect his privacy and sensitive data. The client wants to store his data in an encrypted form on a remote server and retrieve encrypted data without decrypting them. However, encryption of data makes an efficient search difficult. Therefore it is desirable to develop efficient search methods on encrypted data. In this paper, we present a secure and efficient keyword search scheme on encrypted documents. The proposed scheme is built using Bloom filters with a hierarchical structure and enable us to make an efficient conjunctive search. Namely, given the trapdoor of a query Q consisting of q keywords, we can efficiently find documents containing all keywords of Q without decrypting documents using this secure index.