Create and check own SAS

SAS.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace HMac
{
    class Program
    {
        static void Main(string[] args)
        {

            // Generate SAS Key on Server
            byte[] key = Convert.FromBase64String("StorageKeyDFBASE64deadbeef=="); 

            var hmac = new System.Security.Cryptography.HMACSHA256(key);
            string url = "http://www.videost.cdn.com/access?customer=bill&video=fairies.wmv";
            byte[] contentToBeSigned = Encoding.UTF8.GetBytes(url);

            string computedSignatureOnSender = Convert.ToBase64String(hmac.ComputeHash(contentToBeSigned));

            Console.WriteLine(computedSignatureOnSender);
            
            var protectedUrl = string.Format("{0}&sig={1}", url, computedSignatureOnSender);


            // Verify SAS Key on another server by re-calculating the hash over the URL 

            string toBeChecked = protectedUrl.Substring(0, protectedUrl.IndexOf("&sig="));
            string sigFromUrl = protectedUrl.Substring(protectedUrl.IndexOf("&sig=") + 5);
            Console.WriteLine(toBeChecked);

            var hmacVerifier = new System.Security.Cryptography.HMACSHA256(key);
            string recomputedSignatureOnReceiver = Convert.ToBase64String(hmacVerifier.ComputeHash(Encoding.UTF8.GetBytes(toBeChecked)));
        

            bool isAllowed = (sigFromUrl == recomputedSignatureOnReceiver);

            Console.WriteLine(isAllowed ? "gut" : "böse");

        }
    }
}