Practical Secure E-mail Protocols Providing Perfect Forward Secrecy

One of the most important security issues of e-mail service is user privacy. Currently, various security protocols, like PGP(pretty Good Privacy), S/MIME(Secure/Multipurpose Internet Mail Extension), have been proposed. These protocols, however, do not provide forward secrecy. Recently, some security protocols that provide forward secrecy were proposed. But all of them require changes to the current e-mail infrastructure. Moreover, contrary to authors' intention, some of them do not actually provide perfect forward secrecy. In this paper, we propose a new practical e-mail security protocol. The proposed protocol provides perfect forward secrecy and uses a practical e-mail model that dose not require any changes to existing e-mail servers. It encrypts and authenticates messages efficiently using elliptic curve based signcryption scheme. In addition, we provide a way to send secure group e-mails.