Concurrent Encryption and Authentication

Signcryption aims to provide both confidentiality and authentication of messages more efficiently than the independent application of encryption and signature. In the talk, we consider a generic and efficient signcryption scheme featuring parallel encryption and signature on top of a sponge-based message-padding underlying structure. Unlike other existing schemes, the proposed scheme also supports arbitrary long messages. We prove the construction secure when instantiated from weakly secure asymmetric primitives such as a trapdoor one-way encryption and a universal unforgeable signature.