A New Forward-Secure Signcryption Scheme

Signcryption scheme combines digital signature and encryption functions. In regular signcryption, once the long-term private key is compromised, all signatures even those were issued by the honest signer before the compromise, will not be trustworthy any more. In the paper, we present a new forward-secure signcryption scheme. The forward security is that this key update function is one-way and, given the secret key for the current period, it is hard to compute any of the previously used secret keys. So even the adversary gets the secret key, it is still hard to compute any of the previously used secret keys. In this paper, we combine signcryption and forward-secure to present a new signcryption scheme with forward secrecy