I'm currently reading Cory Doctorow's novel Little Brother which includes a part about encrypted messaging, and even wrapping messages first in my private key and then your public key.

I'd like to play around with that but from what I've googled so far it seems to be a rather convoluted process, requiring installing several program components, and creating an encrypted message requires doing some manual file manipulation.

I'm surprised that I can't find something like a Firefox plugin that integrates encryption into Gmail. I've seen that there is a Thunderbird PGP plugin, but I don't use T-bird. I also saw a blog post that Google apparently toyed with PGP support in 2009, but nothing has appeared in the meantime.

Question:
To use encryption with Gmail, is there a simpler method than creating a file locally, then encrypting that file, and finally attaching it to a regular Gmail message?