Golang cipher AES decrypt. How to decode string encoded in Java?

Question

Java

There is a String encoded in Java:

Java

private static final String ALGO = "AES"

    public static String encrypt(String data, String secretKey) throws EKCryptException {
        try {
            Key key = generateKey(secretKey);
            Cipher c = Cipher.getInstance(ALGO);
            c.init(Cipher.ENCRYPT_MODE, key);
            byte[] encVal = c.doFinal(data.getBytes());
            byte[] encoded = Base64.getEncoder().encode(encVal);
            return new String(encoded, "UTF8");
        } catch(Exception ex) {
            log.error("Failure occured while encrypt text value!", ex);
            throw new EKCryptException(data, ex);
        }
    }

    private static Key generateKey(String keyValue) throws EKCryptException {
        try {
            byte[] decodedKey = Base64.getDecoder().decode(keyValue);
            SecretKey originalKey = new SecretKeySpec(decodedKey, 0, decodedKey.length, ALGO); 
            return originalKey;
        } catch(Exception ex) {
            log.error("Failure occured while generate key!", ex);
            throw new EKCryptException("Failure occured while generate key!", ex);
        }
    }

How to decrypt in Go. My attempts give out: cipher: message authentication failed

go

func decode(data string) (string, error)  {
  ciphertext := []byte(data)
  c, err := aes.NewCipher([]byte(DECODE_KEY))
  if err != nil {
    return "", err
  }

  gcm, err := cipher.NewGCMWithNonceSize(c, 0)
  if err != nil {
    return "", err
  }

  nonceSize := 0
  if len(ciphertext) < nonceSize {
    return  "", errors.New("ciphertext too short")
  }

  nonce, ciphertext := ciphertext[:nonceSize], ciphertext[nonceSize:]
  result, err := gcm.Open(nil, nonce, ciphertext, nil)
  if err != nil {
    return "", err
  }
  return string(result), nil
}

Key is naturally the same

Answer 1

My decision

Java

public static String encryptGCM(String data) throws CryptException {
    try {
        SecureRandom random = SecureRandom.getInstanceStrong();
        byte[] iv = new byte[12];
        random.nextBytes(iv);
        log.trace("IV: {}", Arrays.toString(iv));
        Key key = generateGcmKey();
        Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
        GCMParameterSpec spec = new GCMParameterSpec(128, iv);
        cipher.init(Cipher.ENCRYPT_MODE, key, spec);
        byte[] cipherText = cipher.doFinal(data.getBytes("UTF-8"));
        log.trace("encrypted: {}", Arrays.toString(cipherText));
        byte[] result = new byte[cipherText.length + iv.length];
        System.arraycopy(iv, 0, result, 0, iv.length);
        System.arraycopy(cipherText, 0, result, iv.length, cipherText.length);
        log.trace("Not encoded result: {}", Arrays.toString(result));
        return Base64.getEncoder().encodeToString(result);
    } catch (Exception ex) {
        log.error("Failure occured while encrypt text value!", ex);
        throw new CryptException(data, ex);
    }
}

private static Key generateGcmKey() throws CryptException {
    try {
        SecretKey originalKey = new SecretKeySpec(KEY.getBytes(), 0, KEY.getBytes().length, ALGO);
        log.trace("Encoded key: {}", Base64.getEncoder().encodeToString(originalKey.getEncoded()));
        return originalKey;
    } catch (Exception ex) {
        log.error("Failure occured while generate key!", ex);
        throw new CryptException("Failure occured while generate key!", ex);
    }
}

GO

func decode(data string) (string, error) {
  ciphertext, _ := base64.StdEncoding.DecodeString(data)
  key, _ := base64.URLEncoding.DecodeString(decodeKey)
  c, err := aes.NewCipher([]byte(key))
  if err != nil {
    return "", err
  }

  gcm, err := cipher.NewGCM(c)
  if err != nil {
    return "", err
  }

   nonceSize := 12
   if len(ciphertext) < nonceSize {
     return  "", errors.New("ciphertext too short")
   }

   nonce, ciphertext := ciphertext[:nonceSize], ciphertext[nonceSize:]

   result, err := gcm.Open(nil, nonce, ciphertext, nil)
   if err != nil {
     return "", err
   }
   return string(result), nil
 }