Certificateless Public Key Cryptography (CLPKC) enjoys the advantage of ID-based public key cryptography without suffering from the key escrow problem. In 2005, Baek et al. proposed the first certificateless encryption (CLPKE) scheme that does not depend on pairing. Although it provides high efficiency, one drawback of their scheme is that the security proof only holds for a weaker security model in which the Type I adversary is not allowed to replace the public key associated with the challenge identity. In this paper, we eliminate this limitation and construct a strongly secure CLPKE scheme without pairing. We prove that the proposed scheme is secure against adaptive chosen-ciphertext attack in the random oracle model, provided that the Computational Diffie-Hellman problem is intractable. © Springer-Verlag Berlin Heidelberg 2007.
Sun, Y., Zhang, F., & Baek, J. (2007). Strongly secure certificateless public key encryption without pairing. In Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) (Vol. 4856 LNCS, pp. 194–208). Springer Verlag. https://doi.org/10.1007/978-3-540-76969-9_13