Cryptology ePrint Archive: Report 2003/195

Public Key Encryption with keyword Search

Dan Boneh and Giovanni Di Crescenzo and Rafail Ostrovsky and Giuseppe Persiano

Abstract: We study the problem of searching on data that is encrypted using a public key system. Consider user Bob who sends email to user Alice encrypted under Alice's public key. An email gateway wants to test whether the email contains the keyword `urgent' so that it could route the email accordingly. Alice, on the other hand does not wish to give the gateway the ability to decrypt all her messages. We define and construct a mechanism that enables Alice to provide a key to the gateway that enables the gateway to test whether the word `urgent' is a keyword in the email without learning anything else about the email. We refer to this mechanism as <I>Public Key Encryption with keyword Search</I>. As another example, consider a mail server that stores various messages publicly encrypted for Alice by others. Using our mechanism Alice can send the mail server a key that will enable the server to identify all messages containing some specific keyword, but learn nothing else. We define the concept of public key encryption with keyword search and give several constructions.

Category / Keywords: public-key cryptography /

Date: received 22 Sep 2003, last revised 24 Mar 2004

Contact author: dabo at cs stanford edu

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Version: 20040325:014738 (All versions of this report)

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