A browser extension for Chrome/Chromium is being worked on! You can track it at https://github.com/WhisperSystems/TextSecure-Browser
Why is a browser extension needed in this case? Does not the browser expose a source of randomness that would be enough to write the rest of the crypto in JS and use that?
Something that's still OSS and cares about UX (like Signal on iOS) would be fantastic.
I don't understand what's so difficult here. The biggest problem is understanding how PGP works, and having to type a password now and then. I use it all the time, to sign - not encrypt - my mail.
Another study on a different client, but same thing: http://www.scmagazineuk.com/modern-pgp-is-unusable-according...