Calling a ASP.NET Core Web API from a WPF application using Azure AD

Last updated: 20-06-2017
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A WPF application that calls a Web API running on ASP.NET Core protected by Azure AD OAuth Bearer Authentication.

This sample demonstrates a .Net WPF application calling a web API that is secured using Azure AD. The .Net application uses the Active Directory Authentication Library (ADAL) to obtain a JWT access token through the OAuth 2.0 protocol. The access token is sent to the ASP.NET Core Web API, which authenticates the user using the ASP.NET JWT Bearer Authentication middleware.

For more information about how the protocols work in this scenario and other scenarios, see Authentication Scenarios for Azure AD.

This sample been updated to ASP.NET Core GA. Looking for previous versions of this code sample? Check out the tags on the releases GitHub page.

How To Run This Sample

Getting started is simple! To run this sample you will need: - Install .NET Core for Windows by following the instructions at dot.net/core, which will include Visual Studio 2015 Update 3. - An Internet connection - An Azure Active Directory (Azure AD) tenant. For more information on how to get an Azure AD tenant, please see How to get an Azure AD tenant - A user account in your Azure AD tenant. This sample will not work with a Microsoft account, so if you signed in to the Azure portal with a Microsoft account and have never created a user account in your directory before, you need to do that now.

Step 1: Clone or download this repository

From your shell or command line:

git clone https://github.com/Azure-Samples/active-directory-dotnet-native-aspnetcore.git

Step 3: Register the sample with your Azure Active Directory tenant

There are two projects in this sample. Each needs to be separately registered in your Azure AD tenant.

Register the TodoListService web API

  1. Sign in to the Azure portal.
  2. On the top bar, click on your account and under the Directory list, choose the Active Directory tenant where you wish to register your application.
  3. Click on More Services in the left hand nav, and choose Azure Active Directory.
  4. Click on App registrations and choose Add.
  5. Enter a friendly name for the application, for example 'TodoListService' and select 'Web Application and/or Web API' as the Application Type. For the sign-on URL, enter the base URL for the sample, which is by default https://localhost:44351. Click on Create to create the application.
  6. While still in the Azure portal, choose your application, click on Settings and choose Properties.
  7. Find the Application ID value and copy it to the clipboard.
  8. For the App ID URI, enter https:///TodoListService, replacing with the name of your Azure AD tenant.

Register the TodoListClient app

  1. Sign in to the Azure portal.
  2. On the top bar, click on your account and under the Directory list, choose the Active Directory tenant where you wish to register your application.
  3. Click on More Services in the left hand nav, and choose Azure Active Directory.
  4. Click on App registrations and choose Add.
  5. Enter a friendly name for the application, for example 'TodoListClient-DotNet' and select 'Native' as the Application Type. For the Redirect URI, enter https://TodoListClient. Click on Create to create the application.
  6. While still in the Azure portal, choose your application, click on Settings and choose Properties.
  7. Find the Application ID value and copy it to the clipboard.
  8. Configure Permissions for your application - in the Settings menu, choose the 'Required permissions' section, click on Add, then Select an API, and type "TodoListService" in the text box. Then, click on Select Permissions and select 'Access TodoListService'.

Step 4: Configure the sample to use your Azure AD tenant

Configure the TodoListService project

  1. Open the solution in Visual Studio 2015.
  2. In the TodoListService project, open the appsettings.json file.
  3. Find the Tenant property and replace the value with your AAD tenant name, e.g. contoso.onmicrosoft.com.
  4. Find the Audience property and replace the value with the App ID URI you registered earlier, for example https://<your_tenant_name>/TodoListService.

Configure the TodoListClient project

  1. In the TodoListClient project, open App.config.
  2. Find the app key ida:Tenant and replace the value with your AAD tenant name.
  3. Find the app key ida:ClientId and replace the value with the Client ID for the TodoListClient from the Azure portal.
  4. Find the app key ida:RedirectUri and replace the value with the Redirect URI for the TodoListClient from the Azure portal, for example http://TodoListClient.
  5. Find the app key todo:TodoListResourceId and replace the value with the App ID URI of the TodoListService, for example https://<your_tenant_name>/TodoListService
  6. If you changed the default value, find the app key todo:TodoListBaseAddress and replace the value with the base address of the TodoListService project.

Step 5: Trust the IIS Express SSL certificate

Since the web API is SSL protected, the client of the API (the web app) will refuse the SSL connection to the web API unless it trusts the API's SSL certificate. Use the following steps in Windows Powershell to trust the IIS Express SSL certificate. You only need to do this once. If you fail to do this step, calls to the TodoListService will always throw an unhandled exception where the inner exception message is:

"The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel."

To configure your computer to trust the IIS Express SSL certificate, begin by opening a Windows Powershell command window as Administrator.

Query your personal certificate store to find the thumbprint of the certificate for CN=localhost:

PS C:\windows\system32> dir Cert:\LocalMachine\My


    Directory: Microsoft.PowerShell.Security\Certificate::LocalMachine\My


Thumbprint                                Subject
----------                                -------
C24798908DA71693C1053F42A462327543B38042  CN=localhost

Next, add the certificate to the Trusted Root store:

PS C:\windows\system32> $cert = (get-item cert:\LocalMachine\My\C24798908DA71693C1053F42A462327543B38042)
PS C:\windows\system32> $store = (get-item cert:\Localmachine\Root)
PS C:\windows\system32> $store.Open("ReadWrite")
PS C:\windows\system32> $store.Add($cert)
PS C:\windows\system32> $store.Close()

You can verify the certificate is in the Trusted Root store by running this command:

PS C:\windows\system32> dir Cert:\LocalMachine\Root

Step 6: Run the sample

Clean the solution, rebuild the solution, and run it. You might want to go into the solution properties and set both projects as startup projects, with the service project starting first.

Explore the sample by signing in, adding items to the To Do list, removing the user account, and starting again. Notice that if you stop the application without removing the user account, the next time you run the application you won't be prompted to sign-in again - that is the sample implements a persistent cache for ADAL, and remembers the tokens from the previous run.

NOTE: Remember, the To Do list is stored in memory in this TodoListService sample. Each time you run the TodoListService API, your To Do list will get emptied.