Shared authentication cookie for asp net 4 x apps still requires login on one of


ASP.NET is a popular programming language used for web applications. One common challenge faced by developers is the issue of shared authentication . In some cases, even when multiple ASP.NET 4.x apps are using the same authentication cookie, users are still required to log in again when accessing one of the apps. In this article, we will explore this issue and provide a solution with examples.

The Problem

When multiple ASP.NET 4.x apps share the same authentication cookie, users expect to be able to seamlessly between these apps without having to log in again. However, in some cases, users are prompted to log in again when accessing one of the apps, even though they have already themselves in app.

The Solution

To solve this issue, we need to that all the ASP.NET 4.x apps share the same machine key. The machine key is used for encrypting and decrypting sensitive information, such as authentication cookies, in ASP.NET applications.

Step 1: Generating a Machine Key

The step is to generate a machine key that will be used across all the ASP.NET 4.x apps. You can generate a machine key using the code:

using System;
using System.Web.Configuration;

namespace MachineKeyGenerator
    class Program
        static void Main(string[] args)
            string machineKey = System.Web.Security.MachineKey.GenerateNewKey();

After running this code, you will get a machine key that you can use in all your ASP.NET 4.x apps.

Step 2: the Machine Key

Once you have the machine key, you need to configure it in each ASP.NET 4.x app. Open the web.config file of each app and add the following configuration:


Replace “YOUR_VALIDATION_KEY” and “YOUR_DECRYPTION_KEY” with the machine key generated in Step 1.

Step 3: Testing the Solution

After configuring the machine key in all the ASP.NET 4.x apps, you can now test if the shared authentication cookie works as expected. Log in to one of the apps and then navigate to another app. You should not be prompted to log in again, as the authentication cookie will be recognized across all the apps.


By ensuring that all ASP.NET 4.x apps share the same machine key, you can solve the issue of shared authentication cookies requiring users to log in again. This solution provides a seamless user experience when navigating between multiple ASP.NET 4.x apps.

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