New Forward-Secure Signature Scheme with Untrusted Update

摘要

Forward-secure signatures can be used to limit the damage of secret key exposure for digital signatures. In a forward-secure signature scheme, the exposure of current secret key doesn't affect the security of signatures generated in previous periods. In order to integrate this primitive into standard security architectures, Boyen et al. presented a forward-secure signature scheme with untrusted update in the standard model. In this study, we propose another forward-secure signature scheme with untrusted update in the random oracle model. Compared with Boyen's scheme, this scheme has shorter public key, secret key and better key generation algorithm, update algorithm, encrypted key verifying algorithm and signing algorithm. At last, we prove that the scheme is update secure and forward secure under CDH assumption in the random oracle model.