Concisely Indexed Multi-Keyword Rank Search on Encrypted Cloud Documents

With the advent of cloud computing, the low-cost and high-capacity cloud storages have attracted people to move their data from local computers to the remote facilities. People can access and share their data with others at anytime, from anywhere. However, the convenience of cloud storages also comes with new problems and challenges. This paper investigates the problem of secure document search on the cloud. Traditional search schemes use a long index for each document to facilitate keyword search in a large dataset, but long indexes can reduce the search efficiency and waste space. Another concern to prevent people from using cloud storages is the security and privacy problem. Since cloud services are usually run by third party providers, data owners desire to avoid the leakage of their confidential information, and data users desire to protect their privacy when performing search. A trivial solution is to encrypt the data before outsourcing the data to the cloud. However, the encryption could make the search difficult by plain keywords. This paper proposes a secure multi-keyword search scheme with condensed index for encrypted cloud documents. The proposed scheme resolves the issue of long document index and the problem of searching documents over encrypted data, simultaneously. Extended simulations are conducted to show the improvements in terms of time and space efficiency for cloud data search.