using System;

using System.Security.Cryptography;

using System.Text;

public class Program

{

    public static string CreateCheckSum(string accessCode, string secretKey, params string[] listparam)

    {

        var checkSumStr = accessCode + String.Join("", listparam);

​

        //HMAC-SHA1

        Byte[] secretBytes = UTF8Encoding.UTF8.GetBytes(secretKey);

        HMACSHA1 hmac = new HMACSHA1(secretBytes);

​

        Byte[] dataBytes = UTF8Encoding.UTF8.GetBytes(checkSumStr);

        Byte[] calcHash = hmac.ComputeHash(dataBytes);

        string checkSumHash = Convert.ToBase64String(calcHash).Replace(" ", "+").Replace("=", "%3D").Replace("+", "%2B").Replace("/", "%2F");

​

        return checkSumHash;

    }

    public static void Main()

    {

        var inputChecksum = "4579dda647489ba788c0b6f387c64e00468c6812";

        Console.WriteLine("Hello World");

        var accessCode = "e59fba9eb191b9723f766af6ef88fcd9d30c07e4750aac097022d9958938e06e";

        var secretKey = "05c9edab7b677f4d6c345694755f8075f6798fb762aafabbef1a7a2e1fa64dee";

        var msisdn = "0943663693";

        var code = "0943663693";

        var time = "1627558396113";

        var checkSum = CreateCheckSum(accessCode, secretKey, msisdn, code, time);

        Console.WriteLine(checkSum);

    }

}

​

////MerchantCode : VNPTPayAgent_CBH, msisdn: 0943663693, code: 0943663693, time: 1627558396113, check_sum: 4579dda647489ba788c0b6f387c64e00468c6812