gistfile1.cs

using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.IO;
using System.Linq;
using System.Net;
using System.Security.Cryptography;
using System.Text;
using System.Web;

namespace CamTokenGetter
{
    class Program
    {
        static void Main(string[] args)
        {
            ServicePointManager.ServerCertificateValidationCallback = ((sender, certificate, chain, sslPolicyErrors) => true);
            var authexample = new AuthenticationExample();
            authexample.ProcessRequest();
            Console.ReadKey();
        }
    }

    public static class DateTimeHelper
    {
        public static long ToEpochTime(this DateTime dt)
        {
            TimeSpan t = dt - new DateTime(1970, 1, 1);
            long secondsSinceEpoch = (long)t.TotalSeconds;
            return secondsSinceEpoch;
        }
    }

    public class AuthenticationExample
    {
        private static readonly string AUDIENCE = "auth.webtrends.com";
        private static readonly string SCOPE = "sapi.webtrends.com";

        public void ProcessRequest()
        {
            string clientId = "5dc19a573395451cb90330f128807cee.app.webtrends.com"; // set = your client id (client token)
            string secret = "6f6525b6cc1a4ab285023be1a5c2b5ad";  // set = your client secret
            int expMinutes = 10;
            var url = @"https://osauth.webtrends.com/v1/token";

            var assertion = buildAssertion(clientId, secret, expMinutes, 35043, 131);

            var request = new StringDictionary
            { 
                { "client_id",  clientId },
                { "client_assertion", HttpUtility.UrlEncode(assertion) }
            };

            string result = HttpPost(url, request);
            Console.Write(result);
        }

        

        private static string buildAssertion(string clientId, string clientSecret, int expMinutes, int accountId, int userId)
        {
            // Json representation of the header
            string header = "{\"typ\":\"JWT\", \"alg\":\"HS256\"}";
            // Token expiration in minutes
            string exp = DateTime.UtcNow.AddMinutes(expMinutes).ToEpochTime().ToString();
            // Json representation of the claims set
            string claims = "{\"iss\":\"" + clientId + "\",\"prn\":\"" + clientId + "\",\"aud\":\"" + AUDIENCE + "\",\"exp\":" + exp + ",\"scope\":\"" + SCOPE + "\",\"aid\":" + accountId + ",\"uid\":" + userId + " }";
            // Base64Encode the component parts
            string encodedHeader = Base64Encode(header);
            string encodedClaims = Base64Encode(claims);
            // The content to be hashed
            string message = string.Format("{0}.{1}", encodedHeader, encodedClaims);
            // Hash the content, signed with our secret to derive the signature
            HMACSHA256 hmac = new HMACSHA256(Encoding.UTF8.GetBytes(clientSecret));
            byte[] hash = hmac.ComputeHash(Encoding.UTF8.GetBytes(message));
            string signature = Convert.ToBase64String(hash);

            return string.Format("{0}.{1}.{2}", encodedHeader, encodedClaims, signature);
        }

        private static string Base64Encode(string input)
        {
            return Convert.ToBase64String(UTF8Encoding.UTF8.GetBytes(input));
        }

        private static string HttpPost(string url, StringDictionary payload)
        {
            try
            {
                HttpWebRequest req = WebRequest.Create(new Uri(url)) as HttpWebRequest;
                req.Method = "POST";
                req.ContentType = "application/x-www-form-urlencoded";

                var data = new StringBuilder();
                foreach (string key in payload.Keys)
                {
                    data.AppendFormat("{0}={1}&", key, payload[key]);
                }

                byte[] formData = UTF8Encoding.UTF8.GetBytes(data.ToString().TrimEnd('&'));
                req.ContentLength = formData.Length;

                using (var post = req.GetRequestStream())
                {
                    post.Write(formData, 0, formData.Length);
                }

                string result = null;

                using (HttpWebResponse resp = req.GetResponse() as HttpWebResponse)
                {
                    var reader = new StreamReader(resp.GetResponseStream());
                    result = reader.ReadToEnd();
                }

                return result;
            }
            catch (Exception ex)
            {
                Console.Write(ex.Message);
                throw;
            }
        }
    }
}