FingerprintActivity.java

package com.android.launcher3.security.fingerprint;

/**
 * Created by Michele on 20/03/2017.
 */

import android.Manifest;
import android.annotation.TargetApi;
import android.app.Activity;
import android.app.KeyguardManager;
import android.content.pm.PackageManager;
import android.hardware.fingerprint.FingerprintManager;
import android.os.Build;
import android.security.keystore.KeyGenParameterSpec;
import android.security.keystore.KeyPermanentlyInvalidatedException;
import android.security.keystore.KeyProperties;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

import com.android.launcher3.R;

import java.io.IOException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.UnrecoverableKeyException;
import java.security.cert.CertificateException;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;


public class FingerprintActivity extends AppCompatActivity {


    private KeyStore keyStore;
    // Variable used for storing the key in the Android Keystore container
    private static final String KEY_NAME = "FlickLauncher";
    private Cipher cipher;
    private TextView textView;
    private static View shortcutInfo;

    public static Activity getActivity() {
        return activity;
    }

    private static Activity activity;

    public static View getShortcutInfo() {
        return shortcutInfo;
    }

    public static void setShortcutInfo(View shortcutInfo) {
        FingerprintActivity.shortcutInfo = shortcutInfo;
    }

    @Override
    @TargetApi(23)
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_fingerprint);

        activity = this;


        // Initializing both Android Keyguard Manager and Fingerprint Manager
        KeyguardManager keyguardManager = (KeyguardManager) getSystemService(KEYGUARD_SERVICE);
        FingerprintManager fingerprintManager = (FingerprintManager) getSystemService(FINGERPRINT_SERVICE);


        textView = (TextView) findViewById(R.id.errorText);


        // Check whether the device has a Fingerprint sensor.
        if(!fingerprintManager.isHardwareDetected()){
            /**
             * An error message will be displayed if the device does not contain the fingerprint hardware.
             * However if you plan to implement a default authentication method,
             * you can redirect the user to a default authentication activity from here.
             * Example:
             * Intent intent = new Intent(this, DefaultAuthenticationActivity.class);
             * startActivity(intent);
             */
            textView.setText("Your Device does not have a Fingerprint Sensor");
        }else {
            // Checks whether fingerprint permission is set on manifest
            if (ActivityCompat.checkSelfPermission(this, Manifest.permission.USE_FINGERPRINT) != PackageManager.PERMISSION_GRANTED) {
                textView.setText("Fingerprint authentication permission not enabled");
            }else{
                // Check whether at least one fingerprint is registered
                if (!fingerprintManager.hasEnrolledFingerprints()) {
                    textView.setText("Register at least one fingerprint in Settings");
                }else{
                    // Checks whether lock screen security is enabled or not
                    if (!keyguardManager.isKeyguardSecure()) {
                        textView.setText("Lock screen security not enabled in Settings");
                    }else{
                        generateKey();


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


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


        KeyGenerator keyGenerator;
        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);
        }
    }
}