static public TokenPassport CreateTokenPassport(string account, string consumerKey, string consumerSecret, string tokenId, string tokenSecret)
        {
            RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();
            byte[] data = new byte[20];
            rng.GetBytes(data);
            int value = Math.Abs(BitConverter.ToInt32(data, 0));
            string nonce = value.ToString();

            long timestamp = ((long)(DateTime.UtcNow.Subtract(new DateTime(1970, 1, 1))).TotalSeconds);

            string baseString = account + "&" + consumerKey + "&" + tokenId + "&" + nonce + "&" + timestamp;
            string key = consumerSecret + "&" + tokenSecret;
            string signature = "";
            var encoding = new System.Text.ASCIIEncoding();
            byte[] keyBytes = encoding.GetBytes(key);
            byte[] baseStringBytes = encoding.GetBytes(baseString);
            using (var hmacSha1 = new HMACSHA1(keyBytes))
            {
                byte[] hashBaseString = hmacSha1.ComputeHash(baseStringBytes);
                signature = Convert.ToBase64String(hashBaseString);
            }

            return new TokenPassport()
            {
                account = account,
                consumerKey = consumerKey,
                token = tokenId,
                nonce = nonce,
                timestamp = timestamp,
                signature = new TokenPassportSignature
                {
                    algorithm = "HMAC-SHA1",
                    Value = signature
                }
            };
        }