libpam-bitid: A PAM module to use a bitcoin address for credentials.
This is a linux PAM implementation of the BitID protocol. Linux system access is granted using just a bitcoin address.
After a long fight, I managed to add QR code output and http callback to Jay's libpam-bitid. Now you can use your mobile phone to authenticate a ssh session. It works for sudo as well, and probably anything that can output the QR code into the terminal. It probably wouldn't work for a graphical session manager / screensaver.
You can find the fork at
https://github.com/PeterSurda/libpam-bitidCheers,
Peter