A proxy approach to e-mail security

New Internet applications and new releases of existing Internet application s appear with bewildering rapidity. Adding functionality to such applicatio ns can therefore be a time-consuming process. By contrast, Internet protoco ls are significantly less volatile. In some circumstances, the additional f unctionality can be provided by 'tapping into' the protocol exchanges rathe r than modifying the applications themselves, We claim that this represents a more manageable approach to the problem of adding additional facilities to applications. We demonstrate this approach using the example of e-mail s ecurity. Whenever possible, a proxy sitting between a mail client and serve r signs and encrypts outgoing mail. Incoming secured mail is automatically decrypted and verified. This means that any software that works with standa rd mail protocols gains security without requiring separate upgrading, The proxy attempts to keep the amount of user interaction required to a minimum providing security functionality for users without the need to learn a com plex new user interface. Copyright (C) 1999 John Wiley & Sons, Ltd.