use finger print sensor as bio metric

Question

I am new to android bio-metric integration.

Is it possible to use the android devices screen or fingerprint sensor as a biometric device so that users can login into the app without having to use any email or password.

this and this and this as references.

Is using an external fingerprint scanner or biometric the only option or is there an alternative solution ?

This is the code that I've used as a reference. Please have a look at it and let me know how can I get users fingerprint.

MainActivity extends AppCompatActivity {

private FingerprintManager fingerprintManager;
private KeyguardManager keyguardManager;
private KeyStore keyStore;
private KeyGenerator keyGenerator;
private static final String KEY_NAME = "example_key";
private Cipher cipher;
private FingerprintManager.CryptoObject cryptoObject;

@TargetApi(Build.VERSION_CODES.M)
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    keyguardManager =
            (KeyguardManager) getSystemService(KEYGUARD_SERVICE);
    fingerprintManager =
            (FingerprintManager) getSystemService(FINGERPRINT_SERVICE);


    if (!keyguardManager.isKeyguardSecure()) {

        Toast.makeText(this,
                "Lock screen security not enabled in Settings",
                Toast.LENGTH_LONG).show();
        return;
    }

    if (ActivityCompat.checkSelfPermission(this,
            Manifest.permission.USE_FINGERPRINT) !=
            PackageManager.PERMISSION_GRANTED) {
        Toast.makeText(this,
                "Fingerprint authentication permission not enabled",
                Toast.LENGTH_LONG).show();

        return;
    }

    if (!fingerprintManager.hasEnrolledFingerprints()) {

        // This happens when no fingerprints are registered.
        Toast.makeText(this,
                "Register at least one fingerprint in Settings",
                Toast.LENGTH_LONG).show();
        return;
    }

    if (!fingerprintManager.hasEnrolledFingerprints()) {

        // This happens when no fingerprints are registered.
        Toast.makeText(this,
                "Register at least one fingerprint in Settings",
                Toast.LENGTH_LONG).show();
        return;
    }

    generateKey();

    if (cipherInit()) {
        cryptoObject =
                new FingerprintManager.CryptoObject(cipher);
        FingerprintHandler helper = new FingerprintHandler(this);
        helper.startAuth(fingerprintManager, cryptoObject);
    }

}

@TargetApi(Build.VERSION_CODES.M)
protected void generateKey() {
    try {
        keyStore = KeyStore.getInstance("AndroidKeyStore");
    } catch (Exception e) {
        e.printStackTrace();
    }

    try {
        keyGenerator = KeyGenerator.getInstance(
                KeyProperties.KEY_ALGORITHM_AES,
                "AndroidKeyStore");
    } catch (NoSuchAlgorithmException |
            NoSuchProviderException e) {
        throw new RuntimeException(
                "Failed to get KeyGenerator instance", e);
    }

    try {
        keyStore.load(null);
        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) {
        throw new RuntimeException(e);
    }
}

@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);
    }
}
}

Answer 1

I found the solution my self. Turns out that Bio-metric devices provide an encrypted data when the finger print is read by the them. I think due to security reasons the normal finger print sensor present in the phone don't provide this encrypted data. The closest thing a developer can do with the fingerprint sensor is to find out if the fingerprint matches with the already registered fingerprint in the android device. Because of this i had to use a third party sdk.