International Journal of Network Security
Recently, the researchers proposed a slightly different variant of AuthA, based on the scheme proposed by them and provided the first complete proof of forward-secrecy for AuthA. They claimed that under the gap Diffie-Hellman assumption the variant of AuthA was forward-secure in the random-oracle model. In this paper, the authors present an active attack to reveal a previously unpublished flaw in their proof. To fix their proof, they have to introduce one more variant Diffie-Hellman assumption.