A Fast Privacy-Preserving Multi-keyword Search Scheme on Cloud Data

Nowadays, more and more people outsource their data to cloud servers for great flexibility and economic savings. Due to considerations on security, private data is usually protected by encryption before sending to cloud. How to utilize data efficiently while preserving user´s privacy is a new challenge. In this paper, we focus on a efficient multi-keyword search scheme meeting a strict privacy requirement. First, we make a short review of two existing schemes supporting multi-keyword search, the kNN-based MRSE scheme and scheme based on bloom filter. Based on the kNN-based scheme, we propose an improved scheme. Our scheme adopt a product of three sparse matrix pairs instead of the original dense matrix pair to encrypt index, and thus get a significant improvement in efficiency. Then, we combine our improved scheme with bloom filter, and thus gain the ability for index updating. Simulation Experiments show proposed scheme indeed introduces low overhead on computation and storage.