using System;

using System.Security.Cryptography;

using System.Text;

​

public class HMACHelper

{

    public static byte[] HashHMAC(byte[] key, byte[] message)

    {

        var hash = new HMACSHA256(key);

        return hash.ComputeHash(message);

    }

​

    public static string HashHMACHex(string keyHex, string message)

    {

        byte[] hash = HashHMAC(StringEncode(keyHex), StringEncode(message));

        return HashEncode(hash);

    }

​

    public static byte[] StringEncode(string text)

    {

        var encoding = new ASCIIEncoding();

        return encoding.GetBytes(text);

    }

​

    public static string HashEncode(byte[] hash)

    {

        return BitConverter.ToString(hash).Replace("-", "").ToLower();

    }

}