Using JWT to generate a livefyre collection meta jwt token

gistfile1.cs

using Newtonsoft.Json;
using PROJECT.Web.Models;
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Dynamic;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Web;

namespace PROJECT.Web.Helpers
{
    public class LivefyreHelper
    {
        public static String GetNetwork()
        {
            return ConfigurationManager.AppSettings["livefyreNetwork"];
        }

        public static String GetSiteId()
        {
            return ConfigurationManager.AppSettings["livefyreSiteId"];
        }

        public static String GetSiteSecret()
        {
            return ConfigurationManager.AppSettings["livefyreSecretKey"];
        }

        public static String GetCollectionToken(String ID, MetaInfo metaInfo)
        {

            string siteSecret = GetSiteSecret();

            var meta = new Dictionary<string, object>() {
                {"title", metaInfo.Title},
                {"url", metaInfo.Url},
                {"tags", ""},
                {"type", "livecomments"}
            };

            var metaStr = JsonConvert.SerializeObject(meta);

            byte[] hash;
            using (var md5 = MD5.Create())
            {
                hash = md5.ComputeHash(Encoding.UTF8.GetBytes(metaStr));
            }

            StringBuilder sBuilder = new StringBuilder();

            // Loop through each byte of the hashed data  
            // and format each one as a hexadecimal string. 
            for (int i = 0; i < hash.Length; i++)
            {
                sBuilder.Append(hash[i].ToString("x2"));
            }

            meta.Add("articleId", ID);

            string token = JWT.JsonWebToken.Encode(meta, siteSecret, JWT.JwtHashAlgorithm.HS256);

            return token;
        }
    }
}

Updated on 2/24/15 with correct meta.Add