Quickstart: Add sign-in with Microsoft to an ASP.NET Core web app

In this quickstart, you download and run a code sample that demonstrates how an ASP.NET Core web app can sign in users from any Microsoft Entra organization.

Step 1: Configure your application in the Azure portal

For the code sample in this quickstart to work:

• For Redirect URI, enter https://localhost:44321/ and https://localhost:44321/signin-oidc.
• For Front-channel logout URL, enter https://localhost:44321/signout-oidc.

The authorization endpoint will issue request ID tokens.

Step 2: Download the ASP.NET Core project

Run the project.

Step 3: Your app is configured and ready to run

We've configured your project with values of your app's properties, and it's ready to run.

More information

This section gives an overview of the code required to sign in users. This overview can be useful to understand how the code works, what the main arguments are, and how to add sign-in to an existing ASP.NET Core application.

Startup class

The Microsoft.AspNetCore.Authentication middleware uses a Startup class that's run when the hosting process starts:

public void ConfigureServices(IServiceCollection services)
{
    services.AddAuthentication(OpenIdConnectDefaults.AuthenticationScheme)
        .AddMicrosoftIdentityWebApp(Configuration.GetSection("AzureAd"));

    services.AddControllersWithViews(options =>
    {
        var policy = new AuthorizationPolicyBuilder()
            .RequireAuthenticatedUser()
            .Build();
        options.Filters.Add(new AuthorizeFilter(policy));
    });
   services.AddRazorPages()
        .AddMicrosoftIdentityUI();
}

The AddAuthentication() method configures the service to add cookie-based authentication. This authentication is used in browser scenarios and to set the challenge to OpenID Connect.

The line that contains .AddMicrosoftIdentityWebApp adds Microsoft identity platform authentication to your application. The application is then configured to sign in users based on the following information in the AzureAD section of the appsettings.json configuration file:

appsettings.json key	Description
ClientId	Application (client) ID of the application registered in the Azure portal.
Instance	Security token service (STS) endpoint for the user to authenticate. This value is typically https://login.partner.microsoftonline.cn/, indicating the Microsoft Azure operated by 21Vianet.
TenantId	Name of your tenant or the tenant ID (a GUID), or common to sign in users with work or school accounts.

The Configure() method contains two important methods, app.UseAuthentication() and app.UseAuthorization(), that enable their named functionality. Also in the Configure() method, you must register Microsoft Identity Web routes with at least one call to endpoints.MapControllerRoute() or a call to endpoints.MapControllers():

app.UseAuthentication();
app.UseAuthorization();

app.UseEndpoints(endpoints =>
{
    endpoints.MapControllerRoute(
        name: "default",
        pattern: "{controller=Home}/{action=Index}/{id?}");
    endpoints.MapRazorPages();
});

Attribute for protecting a controller or methods

You can protect a controller or controller methods by using the [Authorize] attribute. This attribute restricts access to the controller or methods by allowing only authenticated users. An authentication challenge can then be started to access the controller if the user isn't authenticated.

Help and support

If you need help, want to report an issue, or want to learn about your support options, see Help and support for developers.

Next steps

The GitHub repo that contains this ASP.NET Core tutorial includes instructions and more code samples that show you how to:

• Add authentication to a new ASP.NET Core web application.
• Call Microsoft Graph, other Microsoft APIs, or your own web APIs.
• Add authorization.
• Sign in users in national clouds or with social identities.