On Constructing Certificateless Cryptosystems from Identity Based Encryption
- Cite this paper as:
- Libert B., Quisquater JJ. (2006) On Constructing Certificateless Cryptosystems from Identity Based Encryption. In: Yung M., Dodis Y., Kiayias A., Malkin T. (eds) Public Key Cryptography - PKC 2006. PKC 2006. Lecture Notes in Computer Science, vol 3958. Springer, Berlin, Heidelberg
Certificateless cryptography (CL-PKC) is a concept that aims at enjoying the advantages of identity based cryptography without suffering from its inherent key escrow. Several methods were recently suggested to generically construct a certificateless encryption (CLE) scheme by combining identity based schemes with ordinary public key cryptosystems. Whilst the security of one of these generic compositions was proved in a relaxed security model, we show that all them are insecure against chosen-ciphertext attacks in the strongest model of Al-Riyami and Paterson. We show how to easily fix these problems and give a method to achieve generic CLE constructions which are provably CCA-secure in the random oracle model. We finally propose a new efficient pairing-based scheme that performs better than previous proposals without pre-computation. We also prove its security in the random oracle model.