private static string GenerateToken(User user)
        {
            var sha1Factory = new SHA1CryptoServiceProvider();
            var timestamp = (int)(DateTime.UtcNow.Subtract(new DateTime(1970, 1, 1))).TotalSeconds;
            var unhashed = Encoding.Default.GetBytes(string.Format("{0}{1}{2}", user.Id, user.Username, timestamp));
            var token = BitConverter.ToString(sha1Factory.ComputeHash(unhashed)).Replace("-", "");

            return token.ToLower(CultureInfo.CurrentCulture);
        }
 private static void RefreshUserCache(User user, string token)
 {
     HttpRuntime.Cache.Add(token, user, null, DateTime.Now.AddMinutes(Ttl), TimeSpan.Zero,
         CacheItemPriority.High, null);
 }