A Certificate-Based Signcryption Scheme

In Eurocrypt 2003, Gentry introduced the notion of certificate-based encryption, which combines traditional pubic key encryption (PKE) with identity-based encryption (IBE) while preserving most of the advantages of each, such as no private key escrow and less PKI infrastructure. In this paper, we propose the security notion of certificate-based signcryption and present a concrete certificate-based signcryption scheme derived from pairings on elliptic curves and prove its security in the random oracle model. Additionally, our scheme satisfies the public verifiability and forward secrecy. Compared with the certificate-based sign-then-encrypt scheme, our scheme enjoys shorter message length and less operation cost.