Security Enhanced Public Key Encryption with Keyword Search

Abstract

We propose a security enhanced version of Boneh’s “Public Key Encryption with Keyword Search” system. The server in the new system is equipped with a key pair for performing the search operations. This new system eliminates completely the “secure channel” assumption for the keyword trapdoor. We reexamine the security definition by Baek, point out the weakness of it, and strengthen it such that it is secure against chosen test ciphertext - keyword trapdoor attacks. We discuss the problems met by Baek’s scheme and propose a modified system with full security proofs according to the enhanced security definition in the random oracle model.