/*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License
*/
package com.example.android.fingerprintdialog;
import android.app.Activity;
import android.app.KeyguardManager;
import android.content.Intent;
import android.content.SharedPreferences;
import android.hardware.fingerprint.FingerprintManager;
import android.os.Build;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.security.keystore.KeyGenParameterSpec;
import android.security.keystore.KeyPermanentlyInvalidatedException;
import android.security.keystore.KeyProperties;
import android.support.annotation.Nullable;
import android.util.Base64;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
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.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
/**
* Main entry point for the sample, showing a backpack and "Purchase" button.
*/
public class MainActivity extends Activity {
private static final String TAG = MainActivity.class.getSimpleName();
private static final String DIALOG_FRAGMENT_TAG = "myFragment";
private static final String SECRET_MESSAGE = "Very secret message";
private static final String KEY_NAME_NOT_INVALIDATED = "key_not_invalidated";
static final String DEFAULT_KEY_NAME = "default_key";
private KeyStore mKeyStore;
private KeyGenerator mKeyGenerator;
private SharedPreferences mSharedPreferences;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
try {
mKeyStore = KeyStore.getInstance("AndroidKeyStore");
} catch (KeyStoreException e) {
throw new RuntimeException("Failed to get an instance of KeyStore", e);
}
try {
mKeyGenerator = KeyGenerator
.getInstance(KeyProperties.KEY_ALGORITHM_AES, "AndroidKeyStore");
} catch (NoSuchAlgorithmException | NoSuchProviderException e) {
throw new RuntimeException("Failed to get an instance of KeyGenerator", e);
}
Cipher defaultCipher;
Cipher cipherNotInvalidated;
try {
defaultCipher = Cipher.getInstance(KeyProperties.KEY_ALGORITHM_AES + "/"
+ KeyProperties.BLOCK_MODE_CBC + "/"
+ KeyProperties.ENCRYPTION_PADDING_PKCS7);
cipherNotInvalidated = Cipher.getInstance(KeyProperties.KEY_ALGORITHM_AES + "/"
+ KeyProperties.BLOCK_MODE_CBC + "/"
+ KeyProperties.ENCRYPTION_PADDING_PKCS7);
} catch (NoSuchAlgorithmException | NoSuchPaddingException e) {
throw new RuntimeException("Failed to get an instance of Cipher", e);
}
mSharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
KeyguardManager keyguardManager = getSystemService(KeyguardManager.class);
FingerprintManager fingerprintManager = getSystemService(FingerprintManager.class);
Button purchaseButton = (Button) findViewById(R.id.purchase_button);
Button purchaseButtonNotInvalidated = (Button) findViewById(
R.id.purchase_button_not_invalidated);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
purchaseButtonNotInvalidated.setEnabled(true);
purchaseButtonNotInvalidated.setOnClickListener(
new PurchaseButtonClickListener(cipherNotInvalidated,
KEY_NAME_NOT_INVALIDATED));
} else {
// Hide the purchase button which uses a non-invalidated key
// if the app doesn't work on Android N preview
purchaseButtonNotInvalidated.setVisibility(View.GONE);
findViewById(R.id.purchase_button_not_invalidated_description)
.setVisibility(View.GONE);
}
if (!keyguardManager.isKeyguardSecure()) {
// Show a message that the user hasn't set up a fingerprint or lock screen.
Toast.makeText(this,
"Secure lock screen hasn't set up.\n"
+ "Go to 'Settings -> Security -> Fingerprint' to set up a fingerprint",
Toast.LENGTH_LONG).show();
purchaseButton.setEnabled(false);
purchaseButtonNotInvalidated.setEnabled(false);
return;
}
// Now the protection level of USE_FINGERPRINT permission is normal instead of dangerous.
// See http://developer.android.com/reference/android/Manifest.permission.html#USE_FINGERPRINT
// The line below prevents the false positive inspection from Android Studio
// noinspection ResourceType
if (!fingerprintManager.hasEnrolledFingerprints()) {
purchaseButton.setEnabled(false);
// This happens when no fingerprints are registered.
Toast.makeText(this,
"Go to 'Settings -> Security -> Fingerprint' and register at least one fingerprint",
Toast.LENGTH_LONG).show();
return;
}
createKey(DEFAULT_KEY_NAME, true);
createKey(KEY_NAME_NOT_INVALIDATED, false);
purchaseButton.setEnabled(true);
purchaseButton.setOnClickListener(
new PurchaseButtonClickListener(defaultCipher, DEFAULT_KEY_NAME));
}
/**
* Initialize the {@link Cipher} instance with the created key in the
* {@link #createKey(String, boolean)} method.
*
* @param keyName the key name to init the cipher
* @return {@code true} if initialization is successful, {@code false} if the lock screen has
* been disabled or reset after the key was generated, or if a fingerprint got enrolled after
* the key was generated.
*/
private boolean initCipher(Cipher cipher, String keyName) {
try {
mKeyStore.load(null);
SecretKey key = (SecretKey) mKeyStore.getKey(keyName, 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);
}
}
/**
* Proceed the purchase operation
*
* @param withFingerprint {@code true} if the purchase was made by using a fingerprint
* @param cryptoObject the Crypto object
*/
public void onPurchased(boolean withFingerprint,
@Nullable FingerprintManager.CryptoObject cryptoObject) {
if (withFingerprint) {
// If the user has authenticated with fingerprint, verify that using cryptography and
// then show the confirmation message.
assert cryptoObject != null;
tryEncrypt(cryptoObject.getCipher());
} else {
// Authentication happened with backup password. Just show the confirmation message.
showConfirmation(null);
}
}
// Show confirmation, if fingerprint was used show crypto information.
private void showConfirmation(byte[] encrypted) {
findViewById(R.id.confirmation_message).setVisibility(View.VISIBLE);
if (encrypted != null) {
TextView v = (TextView) findViewById(R.id.encrypted_message);
v.setVisibility(View.VISIBLE);
v.setText(Base64.encodeToString(encrypted, 0 /* flags */));
}
}
/**
* Tries to encrypt some data with the generated key in {@link #createKey} which is
* only works if the user has just authenticated via fingerprint.
*/
private void tryEncrypt(Cipher cipher) {
try {
byte[] encrypted = cipher.doFinal(SECRET_MESSAGE.getBytes());
showConfirmation(encrypted);
} catch (BadPaddingException | IllegalBlockSizeException e) {
Toast.makeText(this, "Failed to encrypt the data with the generated key. "
+ "Retry the purchase", Toast.LENGTH_LONG).show();
Log.e(TAG, "Failed to encrypt the data with the generated key." + e.getMessage());
}
}
/**
* Creates a symmetric key in the Android Key Store which can only be used after the user has
* authenticated with fingerprint.
*
* @param keyName the name of the key to be created
* @param invalidatedByBiometricEnrollment if {@code false} is passed, the created key will not
* be invalidated even if a new fingerprint is enrolled.
* The default value is {@code true}, so passing
* {@code true} doesn't change the behavior
* (the key will be invalidated if a new fingerprint is
* enrolled.). Note that this parameter is only valid if
* the app works on Android N developer preview.
*
*/
public void createKey(String keyName, boolean invalidatedByBiometricEnrollment) {
// The enrolling flow for fingerprint. This is where you ask the user to set up fingerprint
// for your flow. Use of keys is necessary if you need to know if the set of
// enrolled fingerprints has changed.
try {
mKeyStore.load(null);
// Set the alias of the entry in Android KeyStore where the key will appear
// and the constrains (purposes) in the constructor of the Builder
KeyGenParameterSpec.Builder builder = new KeyGenParameterSpec.Builder(keyName,
KeyProperties.PURPOSE_ENCRYPT |
KeyProperties.PURPOSE_DECRYPT)
.setBlockModes(KeyProperties.BLOCK_MODE_CBC)
// Require the user to authenticate with a fingerprint to authorize every use
// of the key
.setUserAuthenticationRequired(true)
.setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_PKCS7);
// This is a workaround to avoid crashes on devices whose API level is < 24
// because KeyGenParameterSpec.Builder#setInvalidatedByBiometricEnrollment is only
// visible on API level +24.
// Ideally there should be a compat library for KeyGenParameterSpec.Builder but
// which isn't available yet.
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
builder.setInvalidatedByBiometricEnrollment(invalidatedByBiometricEnrollment);
}
mKeyGenerator.init(builder.build());
mKeyGenerator.generateKey();
} catch (NoSuchAlgorithmException | InvalidAlgorithmParameterException
| CertificateException | IOException e) {
throw new RuntimeException(e);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_settings) {
Intent intent = new Intent(this, SettingsActivity.class);
startActivity(intent);
return true;
}
return super.onOptionsItemSelected(item);
}
private class PurchaseButtonClickListener implements View.OnClickListener {
Cipher mCipher;
String mKeyName;
PurchaseButtonClickListener(Cipher cipher, String keyName) {
mCipher = cipher;
mKeyName = keyName;
}
@Override
public void onClick(View view) {
findViewById(R.id.confirmation_message).setVisibility(View.GONE);
findViewById(R.id.encrypted_message).setVisibility(View.GONE);
// Set up the crypto object for later. The object will be authenticated by use
// of the fingerprint.
if (initCipher(mCipher, mKeyName)) {
// Show the fingerprint dialog. The user has the option to use the fingerprint with
// crypto, or you can fall back to using a server-side verified password.
FingerprintAuthenticationDialogFragment fragment
= new FingerprintAuthenticationDialogFragment();
fragment.setCryptoObject(new FingerprintManager.CryptoObject(mCipher));
boolean useFingerprintPreference = mSharedPreferences
.getBoolean(getString(R.string.use_fingerprint_to_authenticate_key),
true);
if (useFingerprintPreference) {
fragment.setStage(
FingerprintAuthenticationDialogFragment.Stage.FINGERPRINT);
} else {
fragment.setStage(
FingerprintAuthenticationDialogFragment.Stage.PASSWORD);
}
fragment.show(getFragmentManager(), DIALOG_FRAGMENT_TAG);
} else {
// This happens if the lock screen has been disabled or or a fingerprint got
// enrolled. Thus show the dialog to authenticate with their password first
// and ask the user if they want to authenticate with fingerprints in the
// future
FingerprintAuthenticationDialogFragment fragment
= new FingerprintAuthenticationDialogFragment();
fragment.setCryptoObject(new FingerprintManager.CryptoObject(mCipher));
fragment.setStage(
FingerprintAuthenticationDialogFragment.Stage.NEW_FINGERPRINT_ENROLLED);
fragment.show(getFragmentManager(), DIALOG_FRAGMENT_TAG);
}
}
}
}