How does fingerprint authentication work in mobile

Question

Before implementing, I like to have an idea.Here is how i think it works, The first time user logs in into my app with username and password I save both the user and pass in my app. Second time, user willing to enter the app I give him option to use fingerprint inster of entering usename + password. If he uses fingerprint, I validate it and if validation is successful I use the saved username and password to call the login api. Is this way of thinking, and flow right?

Answer 1

To login with fingerprint API, you have to :

1. Generate a asymmetric key on android
2. send public key to your server
3. prompt user to touch fingerprint
4. if android authenticate user then you have a CryptoObject with your private key
5. sign a payload (for instance user id and a random) and send it to server
6. On server check payload signature with public key

http://android-developers.blogspot.fr/2015/10/new-in-android-samples-authenticating.html