Constructing Pairing-free Certificate-based Encryption

Certificate-based cryptography is a new paradigm that combines traditional public-key cryptography and identity-based cryptography. It not only simplifies the cumbersome certificate management in traditional public-key cryptography, but also eliminates the key escrow and distribution problems inherent in identity-based cryptography. However, all constructions of certificate-based encryption in the literature so far have to be based on the costly bilinear pairings. Therefore, the previous certificate-based encryption schemes are too expensive computationally to be employed in the computation-limited mobile wireless networks. In this paper, we propose a certificate-based encryption scheme that dose not depend on the bilinear pairings. The proposed scheme is proved to be chosenciphertext secure in the random oracle model under the hardness of the RSA problem and the computational Diffie-Hellman problem. Due to avoiding the computationally-heavy bilinear paring operations, the proposed scheme significantly reduces the computational cost and outperforms all the previous certificate-based encryption schemes. This interesting property makes it particularly suitable for the resource-limited mobile devices.