Encrypted Search: Enabling Standard Information Retrieval Techniques for Several New Secure Index Types While Preserving Confidentiality Against an Adversary With Access to Query Histories and Secure Index Contents
Towell, Alexander · ProQuest Demo Repository · 2015
Encrypted Search is a way for a client to store searchable documents on untrusted systems such that the untrusted system can obliviously search the documents on the client's behalf, i.e., the untrusted system does not know what the client is searching for nor what the documents contain. Several new secure index types are designed, analyzed, and implemented. We analyze them with respect to several performance measures: confidentiality, time complexity, space complexity, and search retrieval accuracy. In order to support rank-ordered search, the secure indexes store frequency and proximity information. We investigate the risk this additional information poses to confidentiality and explore ways to mitigate said risk. Separately, we also simulate an adversary who has access to a history of encrypted queries and design techniques that mitigate the risk posed by this adversary.