<?php
   $secret = ""; // Get your secret key from Revlum

   $subId = isset($_GET['subId']) ? $_GET['subId'] : null;
   $transId = isset($_GET['transId']) ? $_GET['transId'] : null;
   $reward = isset($_GET['reward']) ? $_GET['reward'] : null;
   $signature = isset($_GET['signature']) ? $_GET['signature'] : null;

   // Validate Signature
   if(md5($subId . $transId . $reward . $secret) != $signature)
   {
       echo "ERROR: Signature doesn't match";
       return;
   }

   // Further processing can be done here
   echo "Signature is valid. Process the postback.";
?>

from flask import Flask, request, jsonify
import hashlib

app = Flask(__name__)
secret = ""  # Get your secret key from Revlum

@app.route('/postback', methods=['GET'])
def postback():
    subId = request.args.get('subId')
    transId = request.args.get('transId')
    reward = request.args.get('reward')
    signature = request.args.get('signature')

    # Validate Signature
    if hashlib.md5((subId + transId + reward + secret).encode()).hexdigest() != signature:
        return "ERROR: Signature doesn't match", 400

    # Further processing can be done here
    return "Signature is valid. Process the postback."

if __name__ == '__main__':
    app.run()

const express = require('express');
const crypto = require('crypto');
const app = express();
const port = 3000;
const secret = ""; // Get your secret key from Revlum

app.get('/postback', (req, res) => {
    const { subId, transId, reward, signature } = req.query;

    // Validate Signature
    const hash = crypto.createHash('md5').update(subId + transId + reward + secret).digest('hex');
    if (hash !== signature) {
        res.status(400).send("ERROR: Signature doesn't match");
        return;
    }

    // Further processing can be done here
    res.send("Signature is valid. Process the postback.");
});

app.listen(port, () => {
    console.log(`Server is running on http://localhost:${port}`);
});

require 'sinatra'
require 'digest'

secret = "" # Get your secret key from Revlum

get '/postback' do
  subId = params['subId']
  transId = params['transId']
  reward = params['reward']
  signature = params['signature']

  # Validate Signature
  if Digest::MD5.hexdigest(subId + transId + reward + secret) != signature
    halt 400, "ERROR: Signature doesn't match"
  end

  # Further processing can be done here
  "Signature is valid. Process the postback."
end

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

@RestController
public class PostbackController {

    private final String secret = ""; // Get your secret key from Revlum

    @GetMapping("/postback")
    public String postback(@RequestParam String subId, @RequestParam String transId,
                           @RequestParam String reward, @RequestParam String signature) {
        try {
            MessageDigest md = MessageDigest.getInstance("MD5");
            String data = subId + transId + reward + secret;
            md.update(data.getBytes());
            byte[] digest = md.digest();
            StringBuilder sb = new StringBuilder();
            for (byte b : digest) {
                sb.append(String.format("%02x", b));
            }
            if (!sb.toString().equals(signature)) {
                return "ERROR: Signature doesn't match";
            }
        } catch (NoSuchAlgorithmException e) {
            return "ERROR: Unable to process signature";
        }

        // Further processing can be done here
        return "Signature is valid. Process the postback.";
    }
}

using Microsoft.AspNetCore.Mvc;
using System.Security.Cryptography;
using System.Text;

[ApiController]
[Route("postback")]
public class PostbackController : ControllerBase
{
    private readonly string secret = ""; // Get your secret key from Revlum

    [HttpGet]
    public IActionResult Postback(string subId, string transId, string reward, string signature)
    {
        using (var md5 = MD5.Create())
        {
            var input = Encoding.UTF8.GetBytes(subId + transId + reward + secret);
            var hashBytes = md5.ComputeHash(input);
            var hash = BitConverter.ToString(hashBytes).Replace("-", "").ToLower();

            if (hash != signature)
            {
                return BadRequest("ERROR: Signature doesn't match");
            }
        }

        // Further processing can be done here
        return Ok("Signature is valid. Process the postback.");
    }
}