ENCRYPTED SEARCH SYSTEM DESIGN FOR EMAIL CLIENT-SIDE ENCRYPTION

• Main Authors: PATEL, Sarvar, NERGIZ, Ahmet, Erhan, BAUDOIN, Laetitia Estelle, YEO, Kevin, LIDZBORSKI, Nicolas
• Format: Patent
• Language: English; French; German
• Published: 05.04.2023
• Subjects: ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHICCOMMUNICATION

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.