using System.Security.Cryptography;
public static void Main()
Console.WriteLine(hmacSHA256("abcdefgh", "secretkey"));
private static string hmacSHA256(String data, String key)
using (HMACSHA256 hmac = new HMACSHA256(Encoding.ASCII.GetBytes(key))) {
byte[] a2 = hmac.ComputeHash(Encoding.ASCII.GetBytes(data));
string a3 = Convert.ToBase64String(a2).ToString().Replace("+", "-").Replace("/", "_").Replace("=", "");