Gmail and Encryption

There are many programs and scripts that work with Gmail, but what about a web-based method of encrypting and decrypting messages? Sure you could access Gmail through pop3 and have an encryption program like PGP installed and working with an email client like Thunderbird. But what about a method that would work from any computer? What I envision is a Firefox extension that can encrypt and decrypt text on-the-fly. It can also connect to a server or website that stores public-keys for various email users. Private-keys would be encrypted somewhere safe, such as a personal website. Then the extension could grab the private-key, decrypt it when you enter your passcode that was used to encrypt the key, and then decrypt messages right inside Gmail or a new window (some method that would be secure).

Now it would be great if Gmail offered encryption built right in, but they won’t. This might even violate some obscure term of service because you would be encrypting messages and therefore Google would not be able to insert relevant AdWords into your messages. I am also not sure how feasible it is to encrypt and decrypt the messages. If it is done in the browser itself it shouldn’t be too hard because you don’t actually have to get into Gmail but rather analyze webpage content and be able to modify form data.

Now this could all be made much easier by finding a simpler method of encryption and using that method with a select group of people. In that case an extension would encrypt text and refill the compose mail form with that encrypted text. And when you receive encrypted emails the extension would pop-up a window with the decrypted version of that text. This would be done client-side and therefore as secure as the computer you are on is.