通过指纹认证activity和处理程序后如何使用加密对象（密钥）加密android中的内容？

Question

我有下面的源代码来生成密钥并在通过指纹认证后初始化 Chiper 用于加密（使用一些全局变量）

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

@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);
    }
}

在指纹activity

中的指纹认证码后调用函数是这样的

generateKey();

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

这是 FingerprintHandler 代码

private Context context;

// Constructor
public FingerprintHandler(Context mContext) {
    context = mContext;
}

public void startAuth(FingerprintManager manager, FingerprintManager.CryptoObject cryptoObject) {
    CancellationSignal cancellationSignal = new CancellationSignal();
    if (ActivityCompat.checkSelfPermission(context, Manifest.permission.USE_FINGERPRINT) != PackageManager.PERMISSION_GRANTED) {
        return;
    }
    manager.authenticate(cryptoObject, cancellationSignal, 0, this, null);
}

@Override
public void onAuthenticationError(int errMsgId, CharSequence errString) {
    this.update("Fingerprint Authentication error\n" + errString);
}

@Override
public void onAuthenticationHelp(int helpMsgId, CharSequence helpString) {
    this.update("Fingerprint Authentication help\n" + helpString);
}

@Override
public void onAuthenticationFailed() {
    this.update("Fingerprint Authentication failed.");
}

@Override
public void onAuthenticationSucceeded(FingerprintManager.AuthenticationResult result) {
    ((Activity) context).finish();
    Intent intent = new Intent(context, HomeActivity.class);
    context.startActivity(intent);
}

private void update(String e){
    TextView textView = (TextView) ((Activity)context).findViewById(R.id.errorText);
    textView.setText(e);
}

在将 activity 定向到 HomeActivity 的身份验证成功之后，我想使用已经生成的密钥和 HomeActivity 中早些时候已经初始化的 Chiper 加密一些东西，但我不知道如何调用密钥和 Chiper之前已经生成过，有什么例子指纹认证后如何加密？这是我在大学的期末项目，所以我非常感谢任何能回答这个问题的人

Answer 1

一旦您在密钥库中生成了密钥，就非常简单了。你只需要使用相同的初始化向量（IV）来加密和解密。

// encryption
cipher.init(Cipher.ENCRYPT_MODE, key);
byte[] ivBytes = cipher.getIV();
String dataToEncrypt = "Super secret data";
byte[] data = dataToEncrypt.getBytes();
byte[] encryptedData = cipher.doFinal(data);

// decryption
cipher.init(Cipher.DECRYPT_MODE, key, ivBytes);
byte[] decryptedData = cipher.doFinal(encryptedData);
String originalData = new String(decryptedData);

编辑：

我不确定您能否通过活动传递 Cipher，但您肯定可以从任何 activity 检索 KeyStore 中的密钥。您只需要用于生成密钥的密钥名称：

SecretKey cipherKey = (SecretKey) keyStore.getKey("keyName", null);

然后需要重新初始化Cipher

重要提示：每次加密一个数据都需要初始化Cipher，否则会抛出异常提示不能使用两次相同的初始化用于加密的向量 (IV)。

通过指纹认证activity和处理程序后如何使用加密对象（密钥）加密android中的内容？

how to use the crypto object (key) after passing the fingerprint authentication activity and handler to encrypt something in android?

authentication

encryption

android

fingerprint