ENCRYPTED SEARCH WITH NO ZERO-DAY LEAKAGE

A method (900) for providing encrypted search includes receiving, at a user device (10) associated with a user (12), a search query (122) for a keyword (32) that appears in one or more encrypted documents (152) stored on an untrusted storage device (150) and accessing a count table (210) to obtain a count (212) of documents that include the keyword. The method also includes generating a delegatable pseudorandom function (DPRF) (126) based on the keyword, a private cryptographic key (124), and the count of documents. The method also includes evaluating a first portion of the DPRF (126A) and delegating a second portion of the DPRF (126B) to the untrusted storage device which causes the untrusted storage device to evaluate the DPRF and access an encrypted search index (160). The untrusted storage device determines one or more encrypted documents associated with DPRF and returns an identifier (154) for each encrypted document.