MuutHelper.cs

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.Threading.Tasks;
    using System.Security.Cryptography;
    using System.Web.Script.Serialization;

    public class MuutHelper
    {
        #region Instance Fields

        private readonly string _apiKey;

        private readonly string _secretKey;

        private readonly string _timeStamp;

        private string _message;

        private string _userAvatar;

        private string _userDisplayName;

        private string _userEmail;

        private string _userID;

        private bool _userIsAdmin;

        #endregion

        #region Constructors

        public MuutHelper(string apiKey, string secretKey)
        {
            _timeStamp = (DateTime.UtcNow - new DateTime(1970, 1, 1)).TotalSeconds.ToString();

            _apiKey = apiKey;
            _secretKey = secretKey;

            _userAvatar = string.Empty;
            _userDisplayName = string.Empty;
            _userID = string.Empty;
            _userIsAdmin = false;

            this.GenerateMessage();
        }

        #endregion

        #region Properties

        public string ApiKey
        {
            get
            {
                return _apiKey;
            }
        }

        public string Message
        {
            get
            {
                return _message;
            }
        }

        public string Signature
        {
            get
            {
                var encoder = new ASCIIEncoding();
                var messageBytes = encoder.GetBytes(_secretKey + " " + _message + " " + _timeStamp);
                var sha1 = new SHA1Managed();

                var hashValue = sha1.ComputeHash(messageBytes);

                return hashValue.Aggregate("", (current, b) => current + String.Format("{0:x2}", b));
            }
        }

        public string TimeStamp
        {
            get
            {
                return _timeStamp;
            }
        }

        #endregion

        #region Methods and Operators

        #region public

        public void SetUser(string id, string displayname, string email, string avatar, bool isAdmin)
        {
            _userID = id;
            _userDisplayName = displayname;
            _userAvatar = avatar;
            _userIsAdmin = isAdmin;
            _userEmail = email;

            this.GenerateMessage();
        }

        #endregion

        #region private

        private void GenerateMessage()
        {
            var serializer = new JavaScriptSerializer();
            var usr = serializer.Serialize(
                new
                    {
                        user = new
                                   {
                                       displayname = _userDisplayName,
                                       id = _userID,
                                       email = _userEmail,
                                       avatar = _userAvatar,
                                       is_admin = _userIsAdmin
                                   }
                    });

            var encodedbytes = ASCIIEncoding.ASCII.GetBytes(usr);
            _message = Convert.ToBase64String(encodedbytes);
        }

        #endregion

        #endregion
    }