using System;

using System.Net;

using System.Security.Cryptography;

using System.Linq;

using System.Text;

using Newtonsoft.Json;

​

namespace Test

{

    public class SignUpExternalToken

    {

        public string ClientId { get; set; }

        public string UserId { get; set; }

        public string Email { get; set; }

        public string FirstName { get; set; }

        public string LastName { get; set; }

        public string Time { get; set; }

        public string CouponCode { get; set; }

    }

    public class Program

    {

        public static void Main(string[] args)

        {

            string secret = "enRX5617XbJQx0ixthdYZVaqTp72CbEn";

            // declare external token data

            var external =  new SignUpExternalToken(){

                ClientId="d5dd2e22-5a82-4f06-bac6-463ff45c2efe" ,

                Email = "dmartinez+ascap005@mixgenius.com",

                FirstName = "David",

                LastName = null,

                Time= "1486432244276",

                UserId = "123456"

            };

            // generate base64 string from token object

            var externalString = JsonConvert.SerializeObject(external);

            var plainTextBytes = System.Text.Encoding.UTF8.GetBytes(externalString);

            var externalTokenMessage = System.Convert.ToBase64String(plainTextBytes);;

            // extract token data from base64 String

            SignUpExternalToken externalToken;

            var byteArray = Convert.FromBase64String(externalTokenMessage);

            var jsonBack = Encoding.UTF8.GetString(byteArray);

            externalToken = JsonConvert.DeserializeObject<SignUpExternalToken>(jsonBack);

            // prepare values in order

            var tokenValues = new[]

            {

                externalToken.ClientId, externalToken.CouponCode, externalToken.Email, externalToken.FirstName,

                externalToken.LastName, externalToken.Time, externalToken.UserId

            };

            // re-encode message to be decoded

            var message = string.Join(":", tokenValues.Where(s => !string.IsNullOrEmpty(s)));

            // string message = "d5dd2e22-5a82-4f06-bac6-463ff45c2efe:testemail@yopmail.com:Nom:Prenom:123456";

            var encoding = new System.Text.UTF8Encoding();

            byte[] keyByte = encoding.GetBytes(secret);

            byte[] messageBytes = encoding.GetBytes(message);

            using (var hmacsha256 = new HMACSHA256(keyByte))

            {

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

                var hash = Convert.ToBase64String(hashmessage);

                var encodedHash = WebUtility.UrlEncode(hash);

                var encodedExternalTokenMessage = WebUtility.UrlEncode(externalTokenMessage);

                Console.WriteLine("************* Token *************");

                Console.WriteLine(encodedExternalTokenMessage);

                Console.WriteLine("************* Signature *************");

                Console.WriteLine(encodedHash);

                Console.WriteLine("************* copy paste at the end of url *************");

                Console.WriteLine("?t="+encodedExternalTokenMessage+"&s="+encodedHash);

            }

        }

    }

}