Authorization Failure when sending Notification

Asgar Ali 86 Reputation points

I am trying to send Notification to a android device through Azure Notification Hub but i am getting Unauthorized(status code 401).Herre is the code for sending Notification.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using System.Net;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;
using System.Text.Json;
using System.Runtime.Remoting.Messaging;
using System.Net.Http.Json;
using System.Text.Json.Serialization;
using Newtonsoft.Json;
using System.Net.Http.Headers;
using System.Web;
using System.Security.Policy;
using System.Net.Mime;
using Microsoft.SqlServer.Server;

namespace TestSend
    internal class Program
        static void Main(string[] args)
        static async Task PostMessage()
            var client = new HttpClient();
            var se = (int)(DateTime.UtcNow.Subtract(new DateTime(1970, 1, 1))).TotalSeconds + 300;
            var my_uri = HttpUtility.UrlEncode("").ToLower();
            var hash_string = $"my_uri\nse";
            var sha_signature = HttpUtility.UrlEncode(Convert.ToBase64String(EncryptString(hash_string)));
            var Param = HttpUtility.UrlEncode("api-version:2015-04");
            var auth = $"SharedAccessSignature sig={sha_signature}&se={se}&skn=DefaultFullSharedAccessSignature&sr={my_uri}";
            //client.DefaultRequestHeaders.Add("Content-Type", "application/json");
            client.DefaultRequestHeaders.Add("ServiceBusNotification-Format", "gcm");
            client.DefaultRequestHeaders.Add("Authorization", auth);
            // Set the body as appropriate
            var requestBody  = new
                notification = new
                    title = "Notification Hub Test Notification",
                    body = "This is a Test."
                data = new
                    property1 = "value1",
                    property2 = 42

            // Convert the message to JSON
            var jsonMessage = JsonConvert.SerializeObject(requestBody);
            var bodyContent = new StringContent(jsonMessage,Encoding.UTF8,"application/json");
            var url = "";
           client.BaseAddress = new Uri(url);
          // var FullAddress = client.BaseAddress.ToString() ;
            var response = await client.PostAsync("/IRMTNotificationHub/messages/?api-version=2015-04", bodyContent);    
        static byte[] EncryptString(string hash_string)
            var key = Convert.FromBase64String("my key");
            var to_sign = Encoding.UTF8.GetBytes(hash_string);
            using (var hmac = new HMACSHA256(key))
                return hmac.ComputeHash(to_sign);
Azure Notification Hubs
Azure Notification Hubs
An Azure service that is used to send push notifications to all major platforms from the cloud or on-premises environments.
260 questions
An object-oriented and type-safe programming language that has its roots in the C family of languages and includes support for component-oriented programming.
10,206 questions
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Accepted answer
  1. brtrach-MSFT 15,176 Reputation points Microsoft Employee

    The error message "Unauthorized (status code 401)" indicates that the authorization failed. It seems that the issue is with the authorization header. You can try to check the following things:

    Verify that the shared access signature (SAS) token is correct, correctly encoded, has not expired, is for the correct resource, has the correct permissions, is for the correct endpoint and API version and namespace. Also, verify that it's setup for the correct hub, entity, and policy.

    Can you please check these items and let us know if these suggestions resolve the issue? If not, please let us know so we can assist you further.

    1 person found this answer helpful.

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