tencent cloud

{
  "original_type": "transaction", // The type of object before encryption
  "algorithm": "AEAD_AES_256_GCM", // Encryption algorithm
  // Base64-encoded ciphertext
  "ciphertext": "...",
  // Random string initialization vector used for encryption
  "nonce": "...",
  // Additional data packet (may be empty)
  "associated_data": ""
}

import java.io.IOException;
import java.security.GeneralSecurityException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.util.Base64;
import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.GCMParameterSpec;
import javax.crypto.spec.SecretKeySpec;
public class AesUtil {
  static final int KEY_LENGTH_BYTE = 32;
  static final int TAG_LENGTH_BIT = 128;
  private final byte[] aesKey;
  public AesUtil(byte[] key) {
    if (key.length != KEY_LENGTH_BYTE) {
      throw new IllegalArgumentException("Invalid ApiV3Key. The length must be 32 bytes.");
    }
      this.aesKey = key;
  }
  public String decryptToString(byte[] associatedData, byte[] nonce, String ciphertext)
  throws GeneralSecurityException, IOException {
    try {
      Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
      SecretKeySpec key = new SecretKeySpec(aesKey, "AES");
      GCMParameterSpec spec = new GCMParameterSpec(TAG_LENGTH_BIT, nonce);
      cipher.init(Cipher.DECRYPT_MODE, key, spec);
      cipher.updateAAD(associatedData);
      return new String(cipher.doFinal(Base64.getDecoder().decode(ciphertext)), "utf-8");
    } catch (NoSuchAlgorithmException | NoSuchPaddingException e) {
      throw new IllegalStateException(e);
    } catch (InvalidKeyException | InvalidAlgorithmParameterException e) {
      throw new IllegalArgumentException(e);
    }
  }
}

from cryptography.hazmat.primitives.ciphers.aead import AESGCM
import base64
def decrypt(nonce, ciphertext, associated_data):
    key = "Your32Apiv3Key"
    key_bytes = str.encode(key)
    nonce_bytes = str.encode(nonce)
    ad_bytes = str.encode(associated_data)
    data = base64.b64decode(ciphertext)
    aesgcm = AESGCM(key_bytes)
    return aesgcm.decrypt(nonce_bytes, data, ad_bytes)

// DecryptGCM decrypts ciphertext using AES-256-GCM
func DecryptGCM(ciphertext []byte, key []byte, nonce []byte, additionalData []byte) ([]byte, error) {
   block, err := aes.NewCipher(key)
   if err != nil {
      return nil, err
   }
   gcm, err := cipher.NewGCM(block)
   if err != nil {
      return nil, err
   }


   plaintext, err := gcm.Open(nil, nonce, ciphertext, additionalData)
   if err != nil {
      return nil, err
   }
   return plaintext, nil
}