One of the most useful email encryption programs you can use is PGP (Pretty Good Privacy) or if you are like myself, a Free software supporter then you can use its GPLed counterpart called GnuPG (GPG). But with web mail gaining popularity, most people will find the use of these programs to encrypt or even sign their outgoing emails a chore.
Here is where browser plugins come into the picture. Dimitri Popov at linux.com has written a very useful article where he explains how to use the email encryption Firefox plugin called FireGPG to encrypt all your mails in your Gmail account. While KDE users will be aware of and have used KGPG - the front end tool for GnuPG, FireGPG is different in that, as a plugin, it is well integrated with your Firefox web browser and so you need not go outside your Gmail web interface to encrypt, decrypt or sign your mail. It can be done on the fly.
While on this topic of email encryption, I also came across a couple of projects which allow encryption of messages - not preferably emails. They are as follows :
Pidgin-Encryption - It transparently encrypts your instant messages with RSA encryption. It is Easy-to-use, but very secure. Pidgin (aka Gaim) is an instant messenger client for Linux which is used to connect to Yahoo messenger, Microsoft Messenger, AOL talk and many other instant messaging protocols.
OTR - Short for Off The Record messaging allows you to have private messaging using instant messaging and provides the following features - encryption of messages, authentication and deniability. It is also a pidgin plugin.
Gmail S/MIME is another project which provides Firefox users with S/MIME support for Gmail. S/MIME stands for Secure Multi purpose Internet Mail Extensions. S/MIME support is integrated directly into Google's Gmail web interface. It supports reading and sending of encrypted mail.
Lastly, check out this online javascript solution which encrypts and de-crypts your messages using a uniquely generated RSA private key. This project has been developed by the students of Stanford University.
