Two Chosen Plaintext Attacks on the Li-Wang Joint Authentication and Encryption Scheme

In [LW91], Li and Wang proposed a joint authentication and encryption scheme based on algebraic coding theory. They claimed that their scheme is as secure as the Rao-Nam scheme [RN89]. However, in contrast with their claim, it will be shown that this joint authentication and encryption scheme appears to be less secure. In this paper two inherently different chosen-plaintext attacks are presented.