Old thread, I know. I'm experiencing the same exact error a year later.

I was getting "no key" errors, so I imported the key from MIT. Now I'm getting BADSIG warnings. Its happening on the Extras repo, though, I don't have the devel repo added. I deleted and re-added the repo in Application Manager as described above without success. I also specified "diablo" as the distro, no luck.

Is there another place to get the key? I understand its just a warning, but as a long-time Linux guy, this is Not Good(tm).