@ARTICLE{6674958, author={Cao, Ning and Wang, Cong and Li, Ming and Ren, Kui and Lou, Wenjing}, journal={IEEE Transactions on Parallel and Distributed Systems}, title={Privacy-Preserving Multi-Keyword Ranked Search over Encrypted Cloud Data}, year={2014}, volume={25}, number={1}, pages={222-233}, doi={10.1109/TPDS.2013.45}}