Abstract
With the rapid development of Internet, e-mail authentication becomes more and more important. However, many existing e-mail authentication protocols are not secure enough. In 2005, Sun et al. proposed two e-mail protocols and claimed that can provide perfect forward secrecy. In 2007, Raphael showed the weaknesses of the two e-mail protocols.The first protocol can’t securely against unknown keyshare attack and the second protocol can’t provide the perfect forward secrecy. It was contradictory to Sun et al.’s claimed. Therefore in this paper, we propose a novel e-mail protocol using three-party password authenticated key exchange to conquer the weaknesses of Sun et al.’s protocols.