Generic Construction of Certificate-Based Encryption

In Eurocrypt 2003, Gentry introduced a new public key encryption paradigm called certificate-based encryption (CBE) to overcome the drawbacks of the conventional PKI and the identity based encryption (IBE). CBE provides an efficient implicit certification mechanism and allows a periodical update of certificate status while eliminating third-party queries for the certificate status. In addition, it also solves the key escrow problem and key distribution problem in IBE. In this paper, we propose a method to achieve generic CBE constructions from PKE and IBE, which are provably CCA-secure in the random oracle model. Compared to previous generic constructions, the security requirement of the primitive encryption schemes in our method is much weaker.