After dropping and cracking the screen of my iPhone last month, I bought a new iPhone 5s.

I soon became obsessed with Touch ID.

Touch ID allows you to press your thumb to your device to unlock your phone. You can also purchase items from the App Store, iTunes, and iBooks. It’s a convenient way to quickly authenticate on the iPhone.

What if you could also use Touch ID as auth in other apps?

Imagine being able to sign up for a new app just by pressing your thumb to the phone. No more entering your email and password.

You could also log in to existing apps or provide additional auth for banking, stock, and credit card apps. Auth is one of the largest barriers to smoothly using apps on the iPhone.

Obviously, access to Touch ID would need to be supplied by Apple. I’m imagining it could be included as a framework for use by any developer. Apple (or the device itself) could store and supply the user’s credentials to 3rd party applications with the user’s permission.

Of course, Touch ID isn’t without security faults. Unlike a password, you can’t really change your fingerprint if someone happens to get a hold of a copy.

Currently Touch ID is used as a convenience rather than a primary form of authentication. When your iPhone is restarted, your 4-digit passcode (not just your thumbprint) is required.

I’ve been thinking through some ways that Touch ID could be used in conjunction with a second form of identification (device ID, confirmation email) for authentication. I’m not sure I’ve got it completely figured out yet, but it’s fun to speculate.

I’m still fascinated by authentication and new user registration in general. The whole signup, login, logout process is nothing new. However, it is something that can continually be improved and the results can be dramatic.