如何使用Android中的AES-256-GCM用口音加密文本

Question

我尝试用口音加密文本，而节点JS服务器未能解密它，我会得到响应“错误：不支持状态或无法验证数据”。我该怎么办？

这是加密文本的Android文件。

public static String encrypt(String text, String masterKey) throws InvalidKeySpecException, NoSuchAlgorithmException, IOException, IllegalBlockSizeException, InvalidKeyException, BadPaddingException, InvalidAlgorithmParameterException, NoSuchPaddingException {
    byte[] iv = generateIv(16);
    byte[] salt = generateIv(64);
    SecretKey key = getKeyFromPassword(masterKey, salt);
    byte[] cipher = encryptHelper("AES/GCM/NoPadding", text, key,  new GCMParameterSpec(GCM_TAG_LENGTH * 8, iv));
    ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
    byte[] ciphertext = Arrays.copyOfRange(cipher, 0, text.length());
    byte[] tag = Arrays.copyOfRange(cipher, text.length(), cipher.length);
    outputStream.write(salt);
    outputStream.write(iv);
    outputStream.write(tag);
    outputStream.write(ciphertext);
    String base64Encrypted;
    if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        base64Encrypted = Base64.getEncoder().encodeToString(outputStream.toByteArray());
    }else{
        base64Encrypted = android.util.Base64.encodeToString(outputStream.toByteArray(), android.util.Base64.DEFAULT);
    }
    return base64Encrypted;
}
public static byte[] encryptHelper(String algorithm, String input, SecretKey key,
                                   GCMParameterSpec gcmParameterSpec) throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidAlgorithmParameterException, InvalidKeyException, BadPaddingException, IllegalBlockSizeException {

    Cipher cipher = Cipher.getInstance(algorithm);
    cipher.init(Cipher.ENCRYPT_MODE, key, gcmParameterSpec);
    return cipher.doFinal(input.getBytes(StandardCharsets.UTF_8));
}

这是node js文件以解密文本。

function decryptDataTestWork(encdata, masterkey) {
// body...
// base64 decoding
const bData = Buffer.from(encdata, 'base64');

// convert data to buffers
const salt = bData.slice(0, 64);
const iv = bData.slice(64, 80);
const tag = bData.slice(80, 96);
const text = bData.slice(96);

/*console.log(salt);
console.log(iv);
console.log(tag);
console.log(text);*/

// derive key using; 32 byte key length
const key = crypto.pbkdf2Sync(masterkey, salt, 2145, 32, 'sha512');

// AES 256 GCM Mode
const decipher = crypto.createDecipheriv('aes-256-gcm', key, iv);
decipher.setAuthTag(tag);

// encrypt the given text
return decipher.update(text, 'binary', 'utf8') + decipher.final('utf8');
};

我在这里得到了此回应

Error: Unsupported state or unable to authenticate data

，这是文字和钥匙

"description":"Désolé"
"key":"tIJg9tyj2setkg7gknVreP5PXzRQV5J3"

我该怎么做？ 谢谢！

Answer 1

问题是在Java代码中以及Ciphertext和Tag的错误分离中。

您可以从明文大小（由于缺乏填充物而进行GCM）确定Ciphertext大小，但然后假设字符串text具有与字节阵列text.get.bybytes的大小相同（standardCharsets.utf_8），如果在多个字节上编码文本字符，通常不是这种情况。

以下实现使用标签大小将两个部分分开：

byte[] ciphertext = Arrays.copyOfRange(cipher, 0, cipher.length - GCM_TAG_LENGTH);
byte[] tag = Arrays.copyOfRange(cipher, cipher.length - GCM_TAG_LENGTH, cipher.length);

随着此更改，使用NodeJS代码的解密在我的计算机上成功，假设使用相同的密钥（请注意，由于getKeyfeyfrompassword（） is，无法检查键推导爪哇一侧缺少）。

Answer 2

修复后，建议代码的工作非常

public static String encrypt(String text, String masterKey) throws InvalidKeySpecException, NoSuchAlgorithmException, IOException, IllegalBlockSizeException, InvalidKeyException, BadPaddingException, InvalidAlgorithmParameterException, NoSuchPaddingException {
    byte[] iv = generateIv(16);
    byte[] salt = generateIv(64);
    SecretKey key = getKeyFromPassword(masterKey, salt);
    byte[] cipher = encryptHelper("AES/GCM/NoPadding", text, key,  new GCMParameterSpec(GCM_TAG_LENGTH * 8, iv));
    ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
    byte[] ciphertext = Arrays.copyOfRange(cipher, 0, cipher.length - GCM_TAG_LENGTH);
    byte[] tag = Arrays.copyOfRange(cipher, cipher.length - GCM_TAG_LENGTH, cipher.length);
    outputStream.write(salt);
    outputStream.write(iv);
    outputStream.write(tag);
    outputStream.write(ciphertext);
    String base64Encrypted;
    if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        base64Encrypted = Base64.getEncoder().encodeToString(outputStream.toByteArray());
    }else{
        base64Encrypted = android.util.Base64.encodeToString(outputStream.toByteArray(), android.util.Base64.DEFAULT);
    }
    return base64Encrypted;
}
public static SecretKey getKeyFromPassword(String masterKey, byte[] salt) throws NoSuchAlgorithmException, InvalidKeySpecException {

    SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA512");
    KeySpec spec = new PBEKeySpec(masterKey.toCharArray(), salt, 2145, 256);
    return new SecretKeySpec(factory.generateSecret(spec).getEncoded(), "AES");
}
public static byte[] encryptHelper(String algorithm, String input, SecretKey key,
                                   GCMParameterSpec gcmParameterSpec) throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidAlgorithmParameterException, InvalidKeyException, BadPaddingException, IllegalBlockSizeException {

    Cipher cipher = Cipher.getInstance(algorithm);
    cipher.init(Cipher.ENCRYPT_MODE, key, gcmParameterSpec);
    return cipher.doFinal(input.getBytes(StandardCharsets.UTF_8));
}
public static byte[] generateIv(int N) {
    byte[] iv = new byte[N];
    new SecureRandom().nextBytes(iv);
    return iv;
}

感谢@topaco！你救了我！