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Using MSAL Node with the Native Token Broker (Windows)

Microsoft Authentication Library (MSAL) Node supports acquiring tokens from the native token broker. When using the native broker, refresh tokens are bound to the device on which they are acquired and are not accessible by msal-node or the application. This provides a higher level of security that cannot be achieved by msal-node alone.

This article explains how to configure the Windows broker, set up proof-of-possession, and understand broker-specific behavior.

Broker support is available on the following platforms:

Platform Broker Documentation
Windows Web Account Manager (WAM) Windows broker (this article)
macOS Microsoft Enterprise SSO plug-in (Company Portal) macOS broker
Linux Microsoft Single Sign-on for Linux Linux broker

What is a broker

An authentication broker is a component that runs on a user's machine and manages authentication handshakes and token lifecycle for connected accounts. On Windows, this role is performed by Web Account Manager (WAM). Key benefits include:

  • Enhanced security. Security improvements are delivered via OS or broker updates without requiring app code changes. Refresh tokens are device-bound and protected from exfiltration.
  • Feature support. Access to rich OS capabilities such as Windows Hello, Microsoft Entra Conditional Access policies, and Fast Identity Online (FIDO) security keys without extra scaffolding code.
  • System integration. Applications plug into the built-in account picker, allowing users to quickly select an existing account instead of re-entering credentials.
  • Token protection. The broker ensures refresh tokens are device-bound and enables apps to acquire proof-of-possession access tokens.

Supported architectures

  • Windows: x64, x86, ARM64

Prerequisites

  • Node.js 18 or later
  • Install @azure/msal-node-extensions as a dependency
  • Register the broker's redirect URI on your app registration. For the required value, see Redirect URI.

Redirect URI

Register the following redirect URI under the Mobile and desktop applications platform in the Azure portal:

ms-appx-web://Microsoft.AAD.BrokerPlugin/<your-client-id>

Replace <your-client-id> with your application's client ID.

Enable the feature

Enabling token brokering requires just one configuration parameter. Pass a NativeBrokerPlugin instance in the broker configuration:

import { PublicClientApplication, Configuration } from "@azure/msal-node";
import { NativeBrokerPlugin } from "@azure/msal-node-extensions";

const msalConfig: Configuration = {
    auth: {
        clientId: "your-client-id",
    },
    broker: {
        nativeBrokerPlugin: new NativeBrokerPlugin(),
    },
};

const pca = new PublicClientApplication(msalConfig);

Note

msal-node will not fall back to the non-brokered flow in the event of a failure. Only enable the broker flow in environments that support it to avoid unexpected failures.

A working sample can be found in the auth-code-cli-brokered-app sample.

Window parenting

In order for auth prompts to display over the calling application and block further interaction, provide the application's window handle to the acquireTokenInteractive API.

For CLI apps, a best-effort attempt to find the window handle is made under the hood, but it is unreliable.

If you're using Electron, use the getNativeWindowHandle API and pass the result into acquireTokenInteractive:

import { BrowserWindow } from "electron";

const win = new BrowserWindow();
const pca = new PublicClientApplication(msalConfig);

pca.acquireTokenInteractive({
    windowHandle: win.getNativeWindowHandle(),
});

Proof of possession

Access token proof of possession (PoP) is supported when acquiring tokens through the native broker. To request a PoP token, add the following properties to the request object provided to acquireTokenInteractive or acquireTokenSilent:

AT PoP request parameters

Name Description Required
authenticationScheme Indicates whether MSAL should acquire a Bearer or PoP token. Default is Bearer. Required
resourceRequestMethod The all-caps name of the HTTP method of the request that will use the signed token (GET, POST, PUT, etc.) Required
resourceRequestUri The URL of the protected resource for which the access token is being issued Required
shrNonce A server-generated, signed timestamp that is Base64URL encoded as a string. This nonce is used to mitigate clock-skew and time-travel attacks meant to enable PoP token pre-generation. Optional

Usage example

This example requests a proof-of-possession token by setting the authentication scheme and signed HTTP request properties:

import { PublicClientApplication, Configuration, AuthenticationScheme } from "@azure/msal-node";
import { NativeBrokerPlugin } from "@azure/msal-node-extensions";

const msalConfig: Configuration = {
    auth: {
        clientId: "your-client-id",
    },
    broker: {
        nativeBrokerPlugin: new NativeBrokerPlugin(),
    },
};

const pca = new PublicClientApplication(msalConfig);

const popTokenRequest = {
    scopes: ["User.Read"],
    authenticationScheme: AuthenticationScheme.POP,
    resourceRequestMethod: "POST",
    resourceRequestUri: "YOUR_RESOURCE_ENDPOINT",
    shrNonce: "NONCE_ACQUIRED_FROM_RESOURCE_SERVER",
};

pca.acquireTokenInteractive(popTokenRequest);
pca.acquireTokenSilent(popTokenRequest);

Note

Access token proof-of-possession is only supported through the native broker flow and is not available in the non-brokered flow.

Differences when using the Windows broker

There are a few things that may behave differently when acquiring tokens through the native broker:

  • The forceRefresh parameter for acquireTokenSilent calls is not supported. You may receive a cached token from the broker regardless of what this flag is set to.
  • If the broker needs to prompt the user for interaction, a system prompt opens. This changes the user experience (UX) because authentication doesn't occur in a browser window.
  • Access token proof-of-possession is supported by the broker but is not supported by the non-brokered flow.
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