android cipher.doFinal在重新打开应用程序后尝试解密时出现BadPaddingException

Question

问题可能很长，但我将尝试详细描述。

这是一个演示有像我一样的问题。

我有一个Android应用程序，我想添加一个功能，该功能允许用户加密和保存其密码到SharedPreferences中，并从SharedPreferences中读取和解密它们。仅在注册了指纹并且可以将指纹有效用作获取这些密码的验证方式时才可用。

何时存储：

1. 用户输入密码
2. 通过由AndroidKeyStore生成的SecretKey创建加密模式密码

public Cipher getEncryptCipher() {
    try {
        Cipher cipher = Cipher.getInstance(KeyProperties.KEY_ALGORITHM_AES + "/"
                + KeyProperties.BLOCK_MODE_CBC + "/"
                + KeyProperties.ENCRYPTION_PADDING_PKCS7);
        mKeyStore.load(null);
        SecretKey key = (SecretKey) mKeyStore.getKey(KEY_NAME, null);
        cipher.init(Cipher.ENCRYPT_MODE, key);
        return cipher;
    } catch (Exception e) {
        throw new RuntimeException("Failed to encrypt pin ", e);
    }
}

3. FingerprintManager验证密码（密码A）并获得真实的加密密码（密码B）

//mCryptoObject is generated by cipher in step 2
mFingerprintManager.authenticate(mCryptoObject, mCancellationSignal, 0 /* flags */, FingerprintManager.AuthenticationCallback, null);


//in FingerprintManager.AuthenticationCallback
javax.crypto.Cipher cipher = result.getCryptoObject().getCipher();

4. 指纹管理器支持的密码（密码B）的加密密码
5. 将加密的密码和密码iv存储在SharedPreferences中

//In my app, we have many device, every could have one password. Pin is password.
public void encryptPin(String deviceId, String pin, javax.crypto.Cipher cipher) {
    try {
        if (cipher == null) return;
        byte[] encryptedBytes = cipher.doFinal(pin.getBytes("utf-8"));
        byte[] cipherIv = cipher.getIV();
        String encodedPin = Base64.encodeToString(encryptedBytes, Base64.DEFAULT);
        String encodeCipherIv = Base64.encodeToString(cipherIv, Base64.DEFAULT);
        SharedPreferences.Editor editor = mSharedPreferences.edit();
        editor.putString(createPinKey(deviceId), encodedPin);
        editor.putString(createIvKey(deviceId), encodeCipherIv);
        editor.apply();
    } catch (IOException | IllegalBlockSizeException | BadPaddingException e) {
        throw new RuntimeException("Failed to encrypt pin ", e);
    }
}

阅读时：

1. 读取密码iv并创建加密模式密码（Cipher C）

public Cipher getDecryptCipher(String deviceId) {
    try {
        String encodedIv = mSharedPreferences.getString(createIvKey(deviceId), "");
        byte[] cipherIv = Base64.decode(encodedIv, Base64.DEFAULT);
        Cipher cipher = Cipher.getInstance(KeyProperties.KEY_ALGORITHM_AES + "/"
                + KeyProperties.BLOCK_MODE_CBC + "/"
                + KeyProperties.ENCRYPTION_PADDING_PKCS7);
        mKeyStore.load(null);
        SecretKey key = (SecretKey) mKeyStore.getKey(KEY_NAME, null);
        cipher.init(Cipher.DECRYPT_MODE, key, new IvParameterSpec(cipherIv));
        return cipher;
    } catch (Exception e) {
        throw new RuntimeException("Failed to encrypt pin ", e);
    }
}

2. 有效的指纹并获得真实的解密密码（密码D）

//mCryptoObject is generated by cipher in step 1
mFingerprintManager.authenticate(mCryptoObject, mCancellationSignal, 0 /* flags */, FingerprintManager.AuthenticationCallback, null);


//in FingerprintManager.AuthenticationCallback
javax.crypto.Cipher cipher = result.getCryptoObject().getCipher();

3. 读取加密的密码并通过真实的解密密码（密码D）解密

public String decryptPin(String deviceId, javax.crypto.Cipher cipher) {
    String encryptedPin = mSharedPreferences.getString(createPinKey(deviceId), "");
    if (TextUtils.isEmpty(encryptedPin)) {
        return "";
    }
    try {
        if (cipher == null) return "";
        byte[] decodedBytes = Base64.decode(encryptedPin, Base64.DEFAULT);
        //BadPaddingException in this line 
        byte[] decryptBytes = cipher.doFinal(decodedBytes);
        return new String(decryptBytes, Charset.forName("UTF8"));
    } catch (Exception e) {
        MyLog.d(TAG, "Failed to decrypt the data with the generated key." + e.getMessage());
        e.printStackTrace();
        return "";
    }
}

我的初始化方法：

private void init() {
    try {
        mKeyStore = KeyStore.getInstance("AndroidKeyStore");
        mKeyStore.load(null);
        KeyGenParameterSpec.Builder builder = new KeyGenParameterSpec.Builder(KEY_NAME,
                KeyProperties.PURPOSE_ENCRYPT | KeyProperties.PURPOSE_DECRYPT)
                .setBlockModes(KeyProperties.BLOCK_MODE_CBC)
                .setUserAuthenticationRequired(true)
                .setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_PKCS7);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            builder.setInvalidatedByBiometricEnrollment(true);
        }


        KeyGenerator keyGenerator = KeyGenerator.getInstance(KeyProperties.KEY_ALGORITHM_AES, "AndroidKeyStore");
        keyGenerator.init(
                    builder.build());
        keyGenerator.generateKey();


    } catch (Exception e) {
        throw new RuntimeException("Fail to init:" + e);
    }
}

如果不关闭应用程序，一切都很好！！！

但是，当我终止该进程并重新启动它时，在执行cipher.doFinal（）时，在cryptoPin（）方法中得到了BadPaddingException。

System.err: javax.crypto.BadPaddingException
at android.security.keystore.AndroidKeyStoreCipherSpiBase.engineDoFinal(AndroidKeyStoreCipherSpiBase.java:482)
at javax.crypto.Cipher.doFinal(Cipher.java:1502)
at com.xiaomi.smarthome.framework.page.verify.DeviceVerifyConfigCache.decryptPin(DeviceVerifyConfigCache.java:156)
at com.xiaomi.smarthome.framework.page.verify.VerifyManager.decryptPin(VerifyManager.java:173)
at com.xiaomi.smarthome.framework.page.verify.FingerPrintVerifyActivity$1.onAuthenticated(FingerPrintVerifyActivity.java:62)
at com.xiaomi.smarthome.framework.page.verify.view.FingerPrintOpenVerifyDialog.onAuthenticationSucceeded(FingerPrintOpenVerifyDialog.java:136)
at android.hardware.fingerprint.FingerprintManager$MyHandler.sendAuthenticatedSucceeded(FingerprintManager.java:805)
at android.hardware.fingerprint.FingerprintManager$MyHandler.handleMessage(FingerprintManager.java:757)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5458)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:738)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:628)
Caused by: android.security.KeyStoreException: Invalid argument
at android.security.KeyStore.getKeyStoreException(KeyStore.java:632)
at android.security.keystore.KeyStoreCryptoOperationChunkedStreamer.doFinal(KeyStoreCryptoOperationChunkedStreamer.java:224)
at android.security.keystore.AndroidKeyStoreCipherSpiBase.engineDoFinal(AndroidKeyStoreCipherSpiBase.java:473)
... 13 more

有谁能帮助我解决这个问题？是由SecretKey引起的吗？谢谢！！！

Answer 1

我发现了我的问题。在我的init（）方法中生成具有相同别名的Key是我的错。我通过添加判断条件解决了问题？

        if (!mKeyStore.containsAlias(KEY_NAME)) {
            KeyGenerator keyGenerator = KeyGenerator.getInstance(KeyProperties.KEY_ALGORITHM_AES, "AndroidKeyStore");
            keyGenerator.init(
                    builder.build());
            keyGenerator.generateKey();
        }