Hello guys wellcome to the tutorial of fingerprint scanner,

This is a simple tutorial through which you could implement one touch login to your application.

Following are the steps to implement it.

Step 1. Add permission to the manifest file. Eg.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.amitrai.fingerprintauthentication">

<uses-permission
android:name="android.permission.USE_FINGERPRINT" />
.
.
.

Step 2 :- Create an activity and create this methods in it.

> generateKey()  It will generate encryption key which will be store securely on device.

> cipherInit() It initialize the cipher which will be used for creating encrypted FingerPrintManager.

private void generateKey(){

try {

keyStore = KeyStore.getInstance("AndroidKeyStore");

} catch (KeyStoreException e) {

e.printStackTrace();

}



try {

keyGenerator = KeyGenerator.getInstance(KeyProperties.KEY_ALGORITHM_AES,

"AndroidKeyStore");

} catch (NoSuchAlgorithmException e) {

e.printStackTrace();

} catch (NoSuchProviderException e) {

e.printStackTrace();

}



try {

keyStore.load(null);

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {

keyGenerator.init(new

KeyGenParameterSpec.Builder(KEY_NAME,

KeyProperties.PURPOSE_ENCRYPT |

KeyProperties.PURPOSE_DECRYPT)

.setBlockModes(KeyProperties.BLOCK_MODE_CBC)

.setUserAuthenticationRequired(true)

.setEncryptionPaddings(

KeyProperties.ENCRYPTION_PADDING_PKCS7)

.build());

}

keyGenerator.generateKey();

} catch (NoSuchAlgorithmException |

InvalidAlgorithmParameterException

| CertificateException | IOException e) {

e.printStackTrace();

}

}





@TargetApi(Build.VERSION_CODES.M)

public boolean cipherInit() {

try {

cipher = Cipher.getInstance(KeyProperties.KEY_ALGORITHM_AES + "/" + KeyProperties.BLOCK_MODE_CBC + "/" + KeyProperties.ENCRYPTION_PADDING_PKCS7);

} catch (NoSuchAlgorithmException | NoSuchPaddingException e) {

throw new RuntimeException("Failed to get Cipher", e);

}



try {

keyStore.load(null);

SecretKey key = (SecretKey) keyStore.getKey(KEY_NAME,

null);

cipher.init(Cipher.ENCRYPT_MODE, key);

return true;

} catch (KeyPermanentlyInvalidatedException e) {

return false;

} catch (KeyStoreException | CertificateException | UnrecoverableKeyException | IOException | NoSuchAlgorithmException | InvalidKeyException e) {

throw new RuntimeException("Failed to init Cipher", e);

}

}

Step 3 :-  Create a class that implement FingerprintManager.AuthenticationCallback and override all its methods like.

onAuthenticationError



onAuthenticationHelp



onAuthenticationFailed



onAuthenticationSucceeded

Step 4 : -  Apply version checks and hardware checks as fingerpring api is only available in android m so make sure your device is running on marshmallow or above. Also check if device has hardware available for same.

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            //Fingerprint API only available on from Android 6.0 (M)
            FingerprintManager fingerprintManager = (FingerprintManager) activity.getSystemService(Context.FINGERPRINT_SERVICE);
            if (ActivityCompat.checkSelfPermission(activity, Manifest.permission.USE_FINGERPRINT) != PackageManager.PERMISSION_GRANTED) {

Step 5 :-  Call the authenticate method and observe the result on callback.

manager.authenticate(cryptoObject, cancellationSignal, 0, this, null);

That's it you have now implemented one touch login.

You can click this link to see the demo on github.

Happy Coding :)