Google Inc.

Ahmet Erhan Nergiz

Sarvar M Patel

Kevin Yeo

Nicolas Lidzborski

Laetitia Estelle Baudoin

A method for providing encrypted search includes receiving, at a user device associated with a user, a search query for a keyword that appears in one or more encrypted documents stored on an untrusted storage device and accessing a count table to obtain a count of documents that include the keyword. The method also includes generating a delegatable pseudorandom function (DPRF) based on the keyword, a private cryptographic key, and the count of documents. The method also includes evaluating a first portion of the DPRF and delegating a remaining second portion of the DPRF to the untrusted storage device which causes the untrusted storage device to evaluate the DPRF and access an encrypted search index associated with the documents. The untrusted storage device determines one or more encrypted documents associated with DPRF and returns, to the user device, an identifier for each encrypted document associated with the DPRF.

Encrypted search with no zero-day leakage

A method for providing an encrypted search system includes receiving a search query for a keyword that appears in one or more encrypted emails stored on an untrusted storage device and accessing, a count table to obtain a count of unique emails within the emails that include the keyword. The method also includes generating a delegatable pseudorandom function (DPRF) based on the keyword, a private cryptographic key, and the count of unique emails that include the keyword and delegating at least a portion of the DPRF to the untrusted storage device that causes the storage device to evaluate the delegated DPRF, access an encrypted search index associated with the emails, and determine one or more encrypted emails associated with the delegated DPRF based on the encrypted search index. The storage device also returns, to the user device, an identifier for each encrypted email associated with the delegated DPRF.

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Mountain View, CA, United States of America

Ahmet Erhan Nergiz