Android KeyStoreException 未知错误

Question

我正在尝试在用户通过 Android M Fingerprint API 进行身份验证后解密加密文本。我一直在尝试关注 Android Security samples ，以及 KeyGenParameterSpec 中提供的示例文档。我已经能够使用公钥成功加密文本，但是当我使用 DECRYPT_MODE 中的私钥通过 Cipher 调用 cipher.doFinal 时>，我得到一个 KeyStoreException“未知错误”:

03-15 10:06:58.074 14702-14702/com.example.app E/LoginFragment: Failed to decrypt password
        javax.crypto.IllegalBlockSizeException
            at android.security.keystore.AndroidKeyStoreCipherSpiBase.engineDoFinal(AndroidKeyStoreCipherSpiBase.java:486)
            at javax.crypto.Cipher.doFinal(Cipher.java:1502)
            at com.example.app.ui.fragment.util.LoginFragment.onAuthenticationSucceeded(LoginFragment.java:251)
            at com.example.app.ui.controller.FingerprintCallback.onAuthenticationSucceeded(FingerprintCallback.java:21)
            at android.support.v4.hardware.fingerprint.FingerprintManagerCompat$Api23FingerprintManagerCompatImpl$1.onAuthenticationSucceeded(FingerprintManagerCompat.java:301)
            at android.support.v4.hardware.fingerprint.FingerprintManagerCompatApi23$1.onAuthenticationSucceeded(FingerprintManagerCompatApi23.java:96)
            at android.hardware.fingerprint.FingerprintManager$MyHandler.sendAuthenticatedSucceeded(FingerprintManager.java:805)
            at android.hardware.fingerprint.FingerprintManager$MyHandler.handleMessage(FingerprintManager.java:757)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:148)
            at android.app.ActivityThread.main(ActivityThread.java:5417)
            at java.lang.reflect.Method.invoke(Native Method)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
    Caused by: android.security.KeyStoreException: Unknown error
            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)
            at javax.crypto.Cipher.doFinal(Cipher.java:1502) 
            at com.example.app.ui.fragment.util.LoginFragment.onAuthenticationSucceeded(LoginFragment.java:251) 
            at com.example.app.ui.controller.FingerprintCallback.onAuthenticationSucceeded(FingerprintCallback.java:21) 
            at android.support.v4.hardware.fingerprint.FingerprintManagerCompat$Api23FingerprintManagerCompatImpl$1.onAuthenticationSucceeded(FingerprintManagerCompat.java:301) 
            at android.support.v4.hardware.fingerprint.FingerprintManagerCompatApi23$1.onAuthenticationSucceeded(FingerprintManagerCompatApi23.java:96) 
            at android.hardware.fingerprint.FingerprintManager$MyHandler.sendAuthenticatedSucceeded(FingerprintManager.java:805) 
            at android.hardware.fingerprint.FingerprintManager$MyHandler.handleMessage(FingerprintManager.java:757) 
            at android.os.Handler.dispatchMessage(Handler.java:102) 
            at android.os.Looper.loop(Looper.java:148) 
            at android.app.ActivityThread.main(ActivityThread.java:5417) 
            at java.lang.reflect.Method.invoke(Native Method) 
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

当前相关代码如下:

public KeyStore getKeyStore() {
    try {
        return KeyStore.getInstance("AndroidKeyStore");
    } catch (KeyStoreException exception) {
        throw new RuntimeException("Failed to get an instance of KeyStore", exception);
    }
}

public KeyPairGenerator getKeyPairGenerator() {
    try {
        return KeyPairGenerator.getInstance("RSA", "AndroidKeyStore");
    } catch(NoSuchAlgorithmException | NoSuchProviderException exception) {
        throw new RuntimeException("Failed to get an instance of KeyPairGenerator", exception);
    }
}

public Cipher getCipher() {
    try {
        return Cipher.getInstance("RSA/ECB/OAEPWithSHA-256AndMGF1Padding");
    } catch(NoSuchAlgorithmException | NoSuchPaddingException exception) {
        throw new RuntimeException("Failed to get an instance of Cipher", exception);
    }
}

private void createKeyPair() {
    try {
        mKeyPairGenerator.initialize(
                new KeyGenParameterSpec.Builder(KEY_ALIAS, KeyProperties.PURPOSE_DECRYPT)
                        .setDigests(KeyProperties.DIGEST_SHA256, KeyProperties.DIGEST_SHA512)
                        .setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_RSA_OAEP)
                        .setUserAuthenticationRequired(true)
                        .build());
        mKeyPairGenerator.generateKeyPair();
    } catch(InvalidAlgorithmParameterException exception) {
        throw new RuntimeException("Failed to generate key pair", exception);
    }
}

private boolean initCipher(int opmode) {
    try {
        mKeyStore.load(null);

        if(opmode == Cipher.ENCRYPT_MODE) {
            PublicKey key = mKeyStore.getCertificate(KEY_ALIAS).getPublicKey();

            PublicKey unrestricted = KeyFactory.getInstance(key.getAlgorithm())
                    .generatePublic(new X509EncodedKeySpec(key.getEncoded()));

            mCipher.init(opmode, unrestricted);
        } else {
            PrivateKey key = (PrivateKey) mKeyStore.getKey(KEY_ALIAS, null);
            mCipher.init(opmode, key);
        }

        return true;
    } catch (KeyPermanentlyInvalidatedException exception) {
        return false;
    } catch(KeyStoreException | CertificateException | UnrecoverableKeyException
            | IOException | NoSuchAlgorithmException | InvalidKeyException
            | InvalidAlgorithmParameterException exception) {
        throw new RuntimeException("Failed to initialize Cipher", exception);
    }
}

private void encrypt(String password) {
    try {
        initCipher(Cipher.ENCRYPT_MODE);
        byte[] bytes = mCipher.doFinal(password.getBytes());
        String encryptedPassword = Base64.encodeToString(bytes, Base64.NO_WRAP);
        mPreferences.getString("password").set(encryptedPassword);
    } catch(IllegalBlockSizeException | BadPaddingException exception) {
        throw new RuntimeException("Failed to encrypt password", exception);
    }
}

private String decrypt(Cipher cipher) {
    try {
        String encryptedPassword = mPreferences.getString("password").get();
        byte[] bytes = Base64.decode(encryptedPassword, Base64.NO_WRAP);
        return new String(cipher.doFinal(bytes));
    } catch (IllegalBlockSizeException | BadPaddingException exception) {
        throw new RuntimeException("Failed to decrypt password", exception);
    }
}

什么可能导致这个“未知错误”？我已经排除了 setUserAuthenticationRequired，但我不知道是什么原因造成的。我还尝试使用全局 mCipher 而不是 FragmentManagerCompat.AuthenticationCallback.onAuthenticationSucceeded 提供的 Cipher (不过，我认为它们应该是一个和相同)，结果相同。

---

我在寻找 another one of my questions 的答案时遇到了这个问题.

Answer 1

我在 Android Issue Tracker 上找到了答案;根据我的理解，不受限制的 PublicKey 是为解决另一个 known issue 而创建的, 与当前的 Cipher 不兼容。解决方法是在初始化 Cipher 时指定一个 OAEPParameterSpec:

OAEPParameterSpec spec = new OAEPParameterSpec(
        "SHA-256", "MGF1", MGF1ParameterSpec.SHA1, PSource.PSpecified.DEFAULT);

mCipher.init(opmode, unrestricted, spec);