I don't think it's a good idea to use fingerprint as a way to authenticate. Fingerprint is not private data. By "private", I mean as private as a private GPG key. Any fingerprint is able to read a fingerprint as long as you put your finger on it. When there're more fingerprint powered applications, it's gonna be really easy to steal credentials.<p>You may use a passphrase. But that would be as secure as using a passphrase alone.<p>Fingerprint is the public key. The private key would be your hand + your physical presence. However, since fingerprint itself is public, you can't rely on fingerprint to identify physical presence.<p>Unless, you make fingerprint private enough. For example, permanently attach something on to your finger. Instead of providing your fingerprint to third-party application, it generates a key pair based on your fingerprint, and use these keys for authentication.