Enhanced Certificate-Based Encryption from pairings

In Certificate-Based Encryption, introduced by Gentry, a certificate, -or, more generally, a signature-acts not only as a certificate but also as a decryption key. However, the security model of Gentry’s scheme relies on an unrealistic assumption, where the adversary must reveal its partial private key to the challenger in attack games. In this paper, we propose an enhanced Certificate-Based Encryption scheme from pairings in the chosen-key model. We show that this scheme is semantically secure against adaptive chosen ciphertext attacks in the random oracle model under the Bilinear Diffie–Hellman (BDH) assumption. The new scheme not only solves the key escrow problem and the secure channel problem to be inherent in Identity-Based Encryption schemes, but also eliminates the unrealistic assumption of Gentry scheme. Moreover, the proposed scheme is more efficient and secure than the existing related works.