using System;

using System.Linq;

using System.Text;

using System.Security.Cryptography;

​

public class Program

{

    public static void Main()

    {

        string message = "sQ14CZhvGkRwQZGZHnkc6Mu21nAG9yes65855788025298917881569435984105{\"gateway\":\"PAYEEZY\",\"apiKey\":\"sQ14CZhvGkRwQZGZHnkc6Mu21nAG9yes\",\"apiSecret\":\"OqSODWG5krhu1SsY\",\"authToken\":\"fdoa-f7f8a27079f7e5ce07a792fb040894fbf7f8a27079f7e5ce\",\"transarmorToken\":\"NOIW\",\"zeroDollarAuth\":false}";

        string secret = "OqSODWG5krhu1SsY";

        string hash = GetHash(message, secret);

        // expected value produced by signMsg function in sample app

        Console.WriteLine("Expected: B+agJWpCPLO4DtEA7+YlVl8O0fSlR5K0FO2QrkjhFkQ=");

        Console.WriteLine("Actual: " + hash);

    }

​

    public static string GetHash(string message, string secret)

    {

        byte[] keyByte = Encoding.UTF8.GetBytes(secret);

        byte[] messageBytes = Encoding.UTF8.GetBytes(message);

        using (var hmacsha256 = new HMACSHA256(keyByte))

        {

            //01 HMAC SHA256 signed with Payment.js Api Secret

            byte[] hashmessage = hmacsha256.ComputeHash(messageBytes);

            //02 resulting HMAC hash needs to be hex encoded at this point

            string hexEncodedMessage = ByteArrayToHexString(hashmessage);

            //03 encode hex-encoded hash in Base64

            return Convert.ToBase64String(Encoding.UTF8.GetBytes(hexEncodedMessage));

        }

    }

​

    public static string ByteArrayToHexString(byte[] ba)

    {

        StringBuilder hex = new StringBuilder(ba.Length * 2);

        foreach (byte b in ba)

        {

            hex.AppendFormat("{0:X2}", b);

        }

​

        return hex.ToString();

    }

}