using System;
using System.Security.Cryptography;
using System.Text; public static class Program {public static void Main() {byte[] secret = System.Convert.FromBase64String("6fNDiYU0T0/evFpmfycNai/AqF24i+rT0OmuVw0/sGQ=");byte[] ciphertext = System.Convert.FromBase64String("9bIjURJIcwoKvQr+ifOTH3HbMX+IqmsRqHuG/I1GfbSX89JE5DcWh/p8QROC5pRAuYZ7"+"ln7RSkHXJdZpVz1LFQ2859WsetvHHui7qYmfxATOO1j0AQuPdAD3FeRH0kR4s/v3c2nV8"+"1DnUXFCnQER/+VWrYdbu5vn8gm+diSE6CHvkK+ODy0ebVi5O6VBnWVjgBUG33VwWiAyIl"+"7Ik435V55WnZgynH3GfbVYoGwZ5UhYtn3yw2yruiLAKu6VTBvnh/ZJP21cHCJSF6NPSd+8"+"1gzWFU/+ECm3cf3uBbCkmKmL7HxRhRxhG0lMtX6ELZOXuw3eDJ1BTu+sSMkV/5Xk+5XX48"+"XmP6CGZ7KmP7Q3Fw1kZmhn0unFyv0Gw8PjT1Ohny/HMgNl16I=");byte[] nonce = System.Convert.FromBase64String("RYjpCMtUmK54T6Lk");byte[] tag = System.Convert.FromBase64String("FUajWHmZjP4A5qaa1G0kxw==");using (var aes = new AesGcm(secret))

 {var plaintextBytes = new byte[ciphertext.Length];

aes.Decrypt(nonce, ciphertext, tag, plaintextBytes);string decrypt = Encoding.UTF8.GetString(plaintextBytes);

 Console.WriteLine(decrypt);
 }
 }
}

import java.security.Security;
import java.util.Base64;import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;import com.google.common.base.Charsets;import org.apache.commons.lang3.ArrayUtils;
import org.bouncycastle.jce.provider.BouncyCastleProvider;// For Java and JVM-based languages, you might need to install unrestricted policy file for JVM,
// which is provided by Sun. Please refer BouncyCastle FAQ if you get
// java.lang.SecurityException: Unsupported keysize or algorithm parameters or
// java.security.InvalidKeyException: Illegal key size.

// If you cannot install unrestricted policy file for JVM because of some reason, you can try with reflection: See here.public class Test {public static void main(String[] args) {try {
 Security.addProvider(new BouncyCastleProvider());// Data from configuration String keyFromConfiguration = "6fNDiYU0T0/evFpmfycNai/AqF24i+rT0OmuVw0/sGQ=";// Data from server String ivFromHttpHeader = "RYjpCMtUmK54T6Lk";String authTagFromHttpHeader = "FUajWHmZjP4A5qaa1G0kxw==";String httpBody = "9bIjURJIcwoKvQr+ifOTH3HbMX+IqmsRqHuG/I1GfbSX89JE5DcWh/p8QROC5pRAuYZ7"
+"ln7RSkHXJdZpVz1LFQ2859WsetvHHui7qYmfxATOO1j0AQuPdAD3FeRH0kR4s/v3c2nV8"
+"1DnUXFCnQER/+VWrYdbu5vn8gm+diSE6CHvkK+ODy0ebVi5O6VBnWVjgBUG33VwWiAyIl"
+"7Ik435V55WnZgynH3GfbVYoGwZ5UhYtn3yw2yruiLAKu6VTBvnh/ZJP21cHCJSF6NPSd+8"
+"1gzWFU/+ECm3cf3uBbCkmKmL7HxRhRxhG0lMtX6ELZOXuw3eDJ1BTu+sSMkV/5Xk+5XX48"
+"XmP6CGZ7KmP7Q3Fw1kZmhn0unFyv0Gw8PjT1Ohny/HMgNl16I=";// Convert data to process byte[] key = Base64.getDecoder().decode(keyFromConfiguration);byte[] iv = Base64.getDecoder().decode(ivFromHttpHeader);byte[] authTag = Base64.getDecoder().decode(authTagFromHttpHeader);byte[] encryptedText = Base64.getDecoder().decode(httpBody);// Unlike other programming language, We have to append auth tag at the end of
 // encrypted text in Java byte[] cipherText = ArrayUtils.addAll(encryptedText, authTag);// Prepare decryption SecretKeySpec keySpec = new SecretKeySpec(key, 0, 32, "AES");Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
 cipher.init(Cipher.DECRYPT_MODE, keySpec, new IvParameterSpec(iv));
// Decrypt byte[] bytes = cipher.doFinal(cipherText);
 System.out.println(new String(bytes, Charsets.UTF_8));

 } catch (Exception e) {
 e.printStackTrace();
 }
 }
}

function sodium_decrypt( $webhookSecret, $iv_from_http_header, $http_body , $auth_tag_from_http_header ){$key = mb_convert_encoding($webhookSecret, "UTF-8", "BASE64");$iv = mb_convert_encoding($iv_from_http_header, "UTF-8", "BASE64");$cipher_text = mb_convert_encoding($http_body, "UTF-8", "BASE64") . mb_convert_encoding($auth_tag_from_http_header, "UTF-8", "BASE64");$result = sodium_crypto_aead_aes256gcm_decrypt($cipher_text, "", $iv, $key);return $result;

}$webhookSecret = "6fNDiYU0T0/evFpmfycNai/AqF24i+rT0OmuVw0/sGQ=";
$iv_from_http_header = "RYjpCMtUmK54T6Lk";
$auth_tag_from_http_header = "FUajWHmZjP4A5qaa1G0kxw==";
$http_body = "9bIjURJIcwoKvQr+ifOTH3HbMX+IqmsRqHuG/I1GfbSX89JE5DcWh/p8QROC5pRAuYZ7" .
"ln7RSkHXJdZpVz1LFQ2859WsetvHHui7qYmfxATOO1j0AQuPdAD3FeRH0kR4s/v3c2nV8" .
"1DnUXFCnQER/+VWrYdbu5vn8gm+diSE6CHvkK+ODy0ebVi5O6VBnWVjgBUG33VwWiAyIl" .
"7Ik435V55WnZgynH3GfbVYoGwZ5UhYtn3yw2yruiLAKu6VTBvnh/ZJP21cHCJSF6NPSd+8" .
"1gzWFU/+ECm3cf3uBbCkmKmL7HxRhRxhG0lMtX6ELZOXuw3eDJ1BTu+sSMkV/5Xk+5XX48" .
"XmP6CGZ7KmP7Q3Fw1kZmhn0unFyv0Gw8PjT1Ohny/HMgNl16I=";// Decrypt message
$result = sodium_decrypt($webhookSecret, $iv_from_http_header, $http_body , $auth_tag_from_http_header);print($result);

import base64
from Cryptodome.Cipher import AES def decrypt_AES_GCM(encryptedMsg, authTag, secretKey, iv):
 iv = base64.b64decode(iv)
 encryptedMsg = base64.b64decode(encryptedMsg)
 secretKey = base64.b64decode(secretKey)
 authTag = base64.b64decode(authTag)
 aesCipher = AES.new(secretKey, AES.MODE_GCM, iv)
 plaintext = aesCipher.decrypt_and_verify(encryptedMsg, authTag)return plaintext

 example = {"encoded" : "9bIjURJIcwoKvQr+ifOTH3HbMX+IqmsRqHuG/I1GfbSX89JE5DcWh/p8QROC5pRAuYZ7" \
"ln7RSkHXJdZpVz1LFQ2859WsetvHHui7qYmfxATOO1j0AQuPdAD3FeRH0kR4s/v3c2nV8" \
"1DnUXFCnQER/+VWrYdbu5vn8gm+diSE6CHvkK+ODy0ebVi5O6VBnWVjgBUG33VwWiAyIl" \
"7Ik435V55WnZgynH3GfbVYoGwZ5UhYtn3yw2yruiLAKu6VTBvnh/ZJP21cHCJSF6NPSd+8" \
"1gzWFU/+ECm3cf3uBbCkmKmL7HxRhRxhG0lMtX6ELZOXuw3eDJ1BTu+sSMkV/5Xk+5XX48"
"XmP6CGZ7KmP7Q3Fw1kZmhn0unFyv0Gw8PjT1Ohny/HMgNl16I=","iv" : "RYjpCMtUmK54T6Lk","tag" : "FUajWHmZjP4A5qaa1G0kxw==","secret" : "6fNDiYU0T0/evFpmfycNai/AqF24i+rT0OmuVw0/sGQ="}


result = decrypt_AES_GCM(example['encoded'], example['tag'], example['secret'], example['iv'])
print(result)