Weakness of an ElGamal-Like Cryptosystem for Enciphering Large Messages

摘要

In 2002, Hwang et al. proposed an ElGamal-like cryptosystem for enciphering large message where it modified from ElGamal cryptosystem. They believe their scheme is based on the difficulty of finding the composite exclusive-or operation. Although, they used bitwise exclusive-or to against multiplicative attack. For this scheme, it is still insecure. In this paper, we give a proof to certain that we claimed.