Practical and Secure E-Mail System (PractiSES)

In this paper, a practical and secure e-mail system (called “PractiSES”) that performs public key distribution and management in a unique way is proposed. PractiSES is a network of several domains. At the domain level, a designated PractiSES server, which is trusted by all users of that domain, distributes the public keys. If a user needs another user’s public key at a different domain, then inter-domain communication is carried out. PractiSES clients manage their public keys and obtain public keys of other users by using unique, secure and user-transparent protocols. PractiSES clients can exchange e-mails in encrypted and/or signed fashion. Since on-demand fetching of public keys is aimed in PractiSES, use of certificates is limited for inter-domain communications only; no certificates are used within a domain. Our simulations show that a state-of-the-art PC would be sufficient to serve as PractiSES server of a medium-size organization.