Two birds one stone: Signcryption using RSA

Abstract

Signcryption is a public key primitive proposed by Zheng [14] to achieve the combined functionality of digital signature and encryption in an efficient manner. We present a signcryption scheme based on RSA and provide proofs of security in the random oracle model [6] for its privacy and unforgeability. Both proofs are under the assumption that inverting the RSA function is hard. Our scheme has two appealing aspects to it. First of all it produces compact ciphertexts. Secondly it offers non-repudiation in a very straight-forward manner. © Springer-Verlag Berlin Heidelberg 2003.