Authorize with a specific scheme

In some scenarios, such as Single Page Applications (SPAs), it's common to use multiple authentication methods. For example, the app may use cookie-based authentication to log in and JWT bearer authentication for JavaScript requests. In some cases, the app may have multiple instances of an authentication handler. For example, two cookie handlers where one contains a basic identity and one is created when a multi-factor authentication (MFA) has been triggered. MFA may be triggered because the user requested an operation that requires extra security.

An authentication scheme is named when the authentication service is configured during authentication. For example:

public void ConfigureServices(IServiceCollection services)
{
    // Code omitted for brevity

    services.AddAuthentication()
        .AddCookie(options => {
            options.LoginPath = "/Account/Unauthorized/";
            options.AccessDeniedPath = "/Account/Forbidden/";
        })
        .AddJwtBearer(options => {
            options.Audience = "http://localhost:5001/";
            options.Authority = "http://localhost:5000/";
        });

In the preceding code, two authentication handlers have been added: one for cookies and one for bearer.

Note

Specifying the default scheme results in the HttpContext.User property being set to that identity. If that behavior isn't desired, disable it by invoking the parameterless form of AddAuthentication.

Selecting the scheme with the Authorize attribute

At the point of authorization, the app indicates the handler to be used. Select the handler with which the app will authorize by passing a comma-delimited list of authentication schemes to [Authorize]. The [Authorize] attribute specifies the authentication scheme or schemes to use regardless of whether a default is configured. For example:

[Authorize(AuthenticationSchemes = "Cookie,Bearer")]
public class MixedController : Controller

In the preceding example, both the cookie and bearer handlers run and have a chance to create and append an identity for the current user. By specifying a single scheme only, the corresponding handler runs.

[Authorize(AuthenticationSchemes = "Bearer")]
public class MixedController : Controller

In the preceding code, only the handler with the "Bearer" scheme runs. Any cookie-based identities are ignored.

Selecting the scheme with policies

If you prefer to specify the desired schemes in policy, you can set the AuthenticationSchemes collection when adding your policy:

services.AddAuthorization(options =>
{
    options.AddPolicy("Over18", policy =>
    {
        policy.AuthenticationSchemes.Add("Bearer");
        policy.RequireAuthenticatedUser();
        policy.Requirements.Add(new MinimumAgeRequirement());
    });
});

In the preceding example, the "Over18" policy only runs against the identity created by the "Bearer" handler. Use the policy by setting the [Authorize] attribute's Policy property:

[Authorize(Policy = "Over18")]
public class RegistrationController : Controller