US Patent 11250151 Encrypted search over encrypted data with reduced volume leakage

A method for performing encrypted search includes receiving a search query for a plurality of keywords from a user device that appear in one or more encrypted documents stored on an untrusted storage device. The method also includes accessing an encrypted search index to obtain a first list of document identifiers each representative of a document that includes a first keyword and a second keyword of the plurality of keywords. The method also includes, for each remaining keyword, determining a corresponding list of document identifiers each representative of a document that includes the first, second, and respective remaining keyword. The method includes determining, based on the first list of document identifiers and each corresponding list of document identifiers, a second list of document identifiers each representative of a document that includes each of the plurality of keywords. The method also includes returning the second list to the user device.