using System;

using System.Text;

using System.Security.Cryptography;

​

public class Program

{

    public static void Main()

    {

        //string text = "{\"amount\":\"150.00\",\"buttontext\":\"test\",\"control\":\"92\",\"currency\":\"PLN\",\"description\":\"czesne - rata 1\",\"id\":\"782076\",\"paramsList\":\"amount;buttontext;control;currency;description;id;type\",\"type\":\"0\"}";

        //?amount=150.00&buttontext=test&chk=6ef8311ecbfcd4990ec37e30c64b101209c5e95e82d50b3d194a4c65d4b0a29f&control=92&currency=PLN&description=czesne+-+rata+1&id=782076&type=0

        //działa poprawnie

        string text = "{\"amount\":\"150.00\",\"buttontext\":\"test\",\"control\":\"92\",\"currency\":\"PLN\",\"description\":\"czesnę - rata 1\",\"id\":\"782076\",\"paramsList\":\"amount;buttontext;control;currency;description;id;type\",\"type\":\"0\"}";     

        //?amount=150.00&buttontext=test&chk=fc81f863914d5fd62cb1892c87c90235d12645f517d1f7c86e98042f1eae4207&control=92&currency=PLN&description=czesn%c4%99+-+rata+1&id=782076&type=0

        //poprawne według Dotpay chk=2763ca62e7e436e0eb52879775442aed8819ac0568263e8fab5890154b397172

        string key = "0spzSEImUtlN4zZB7NFVUxsrS9ui7nCc";

        UTF8Encoding encoding = new UTF8Encoding();

        Byte[] textBytes = encoding.GetBytes(text);

        Byte[] keyBytes = encoding.GetBytes(key);  

        //test

        Encoding utf8 = Encoding.UTF8;              

        Encoding utf7 = Encoding.UTF7;      

        Encoding utf16 = Encoding.Unicode;      

        Encoding ascii = Encoding.ASCII;

​

        textBytes = utf8.GetBytes(text);

        keyBytes = utf8.GetBytes(key);

​

        Byte[] hashBytes;

        using (HMACSHA256 hash = new HMACSHA256(keyBytes))

           hashBytes = hash.ComputeHash(textBytes);

​

        Console.WriteLine("Hash chk: " + BitConverter.ToString(hashBytes).Replace("-", "").ToLower());

    }

}