Forward-Secure Certificate-Based Encryption

Certificate-based encryption (CBE) is a new paradigm which overcomes the shortcomings of traditional public-key encryption (PKE) and identity based encryption (IBE). CBE provides an efficient implicit certificate mechanism to eliminate third-party queries for the certificate status and to simplify the certificate revocation problem in traditional PKI. Therefore, CBE can be used to construct an efficient PKI requiring fewer infrastructures. It also solves the key escrow and key distribution problem inherent in IBE. In this paper, we introduce a new notion called Forward-Secure Certificate-Based Encryption. It preserves the advantages of CBE such as implicit certificate and no private key escrow. At the same time it also inherits the properties of the forward-secure public key encryption. We also propose a concrete and efficient forward-secure CBE scheme and prove it to be secure based on the bilinear Diffie-Hellman assumption in the random oracle model.