关键词: 代理重加密, 基于证书密码体制, 双线性对, 选择密文安全

Abstract: The previous constructions of certificate-based proxy re-encryption are heavily dependent on the costly bilinear pairings, and thus have low computation efficiency. To solve this problem, an efficient certificate-based proxy re-encryption scheme with bilinear pairings is developed. This new scheme significantly reduces the computation cost because it requires computing no bilinear pairings in the encryption algorithm and at most one bilinear pairing in other algorithms. Compared with the previous certificate-based proxy re-encryption schemes, it enjoys obvious advantage in both the computation efficiency and the communication cost. In the random oracle model, the proposed scheme is formally proven to achieve indistinguishability against adaptively chosen-ciphertext attacks （i.e., chosen-ciphertext security） under the hardness assumption of the modified Bilinear Diffie-Hellman Inversion for q-values [(q-mBDHI)] problem and the 1-Bilinear Diffie-Hellman Inversion [(1-BDHI)] problem.

Key words: proxy re-encryption, certificate-based cryptography, bilinear pairing, chosen-ciphertext security