Public key encryption with authorized keyword search

Abstract

Public key encryption with keyword search (PEKS) provides an elegant mechanism for a user to identify the specific encrypted data. PEKS protects data against disclosure while making it searchable. In this paper, we propose a new cryptographic primitive called public key encryption with authorized keyword search (PEAKS). In PEAKS, keywords are encrypted with one public key and users without corresponding secret key need authorization from the authority to search keywords. We present a concrete PEAKS construction which allows the authority to authorize users to search different keyword sets. The proposed scheme features with the constant-size authorized token, independent of the size of keyword set size, which cuts down bandwidth consumption considerably. This property makes our PEAKS quite useful when the authorized token needs to be frequently updated with time for security purpose. The semantical security against chosen keyword attack and trapdoor unforgeability are formally proved.