An ElGamal-like Secure Channel Free Public Key Encryption with Keyword Search Scheme

Abstract

The idea of public key encryption with keyword search (PEKS), proposed by Boneh et al., enables one to send a trapdoor containing a encrypted keyword to query data without revealing the keyword. In Boneh et al.’s design, the trapdoor has to be transferred through a secure channel, which is both costly and inefficient. Baek et al. then proposed an efficient secure channel free public key encryption scheme with keyword search (SCF-PEKS). After that, vast amounts of research have focused on the protection against the off-line keyword guessing attack (OKGA) by enhancing the model. However, most of the PEKS/SCF-PEKS schemes developed so far are constructed by applying bilinear pairing and are susceptible to off-line keyword guessing attacks. In this paper, we propose a new SCF-PEKS scheme based on the ElGamal cryptosystem. The proposed scheme is not only secure against off-line keyword guessing attacks but also improves the efficiency.