Comments on e-mail protocols providing forward secrecy
Ya‐Fen Chang, Chin‐Chen Chang, Wei‐Liang Tai · Journal of Discrete Mathematical Sciences and Cryptography · 2006
E-mail (electronic mail) plays an important role to transfer various types of electronic data via the Internet. The e-mail systems usually employ the conventional and public key cryptographic systems to deliver the e-mails efficiently and securely. Since perfect forward secrecy is not ensured in them, Sun et al. therefore proposed two new e-mail protocols to provide perfect forward secrecy. Nevertheless, their second protocol actually either does not achieve the requirement or suffers from the off-line password guessing attack.