Abstract: Public key encryption with keyword search (PEKS) is a useful cryptographic primitive which allows one to delegate to an untrusted storage server the capability of searching on publicly encrypted data without impacting the security and privacy of original  data. However, due to lack of data encryption and decryption function, a PEKS scheme cannot be used alone but has to be coupled with a standard public key encryption (PKE) scheme. For this reason, a new cryptographic primitive called integrated PKE and PEKS (PKE+PEKS) was introduced by Baek et al. in 2006, which provides the functions of both PKE and PEKS. So far, several PKE+PEKS schemes have been proposed in the literature. However, none of them considers the keyword guessing attack. This paper proposes a new efficient PKE+PEKS scheme which can resist keyword guessing attacks. Compared with other existed scheme, the performance of this scheme is greatly improved and we needn’t use bilinear pairing in the generation of ciphertext of keywords and data, which reduces the cost of computation and storage. The security analysis shows that the scheme proposed in this paper can satisfy the security of ciphertext privacy, the trapdoor indistinguishability and the keyword guessing attack respectively. Efficiency analysis shows that the proposed scheme is more efficient.

Key words: ciphertext search, public key encryption, keyword guessing attack, PKE+PEKS