Joint signature and encryption in the presence of continual leakage

Abstract

The goal of leakage-resilient cryptography is to build schemes secure even if the secrets are partially leaked to the adversary. As far as we know, most existing leakage-resilient cryptographic schemes are studied in the setting of single secret, e.g., signing key of signature scheme, decryption key of encryption scheme. In this paper, we study the case of double secrets, i.e., the notion of a joint signature and encryption in the presence of continual leakage, for the first time. Following the terminology of [2], we refer to this primitive as leakage-resilient signcryption. In particular, we give two instantiations of such signcryption scheme based on existing leakage resilient signature and encryption schemes.