using System;

using System.Text;

using System.Security.Cryptography;

public class Program

{

    public static void Main()

    {

        String Timestamp = "1611232922428";

        String Nonce = "5RhaTrZPhknNv0kDSA2UQ67cPMVNS4sA";

​

        String Body = "{\"merchantId\":\"98765987\",\"subMerchantId\":\"98765987\",\"merchantTradeNo\":\"9825382937292\",\"totalFee\":25.17,\"productDetail\":\"Greentea ice cream cone\",\"currency\":\"BUSD\",\"returnUrl\":\"\",\"tradeType\":\"APP\",\"productType\":\"Food\",\"productName\":\"Ice Cream\"}";

​

        String Payload = (Timestamp + "\n" + Nonce + "\n" + Body + "\n");

​

        String SecretKey = "uahr4nhailyq55yubuhuncnprfac73bcbz2qfafsevic1jruwunioxtoaozy122f";

​

        HMACSHA512 HMAC = new HMACSHA512(Encoding.UTF8.GetBytes(SecretKey));

​

        String Signature = BitConverter.ToString(HMAC.ComputeHash(Encoding.UTF8.GetBytes(Payload))).Replace("-","");

​

        Console.WriteLine("Signature: " + Signature);

    }

}

​