Скачать или смотреть How to Embed Client ID in Azure AD Token for ASP.NET Core API Authentication

Learn how to resolve issues with embedding the `App Registration Client ID` in Azure AD tokens for your ASP.NET Core API through effective configurations.
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How to Embed Client ID in Azure AD Token for ASP.NET Core API Authentication

When developing an ASP.NET Core API that utilizes Azure Active Directory (Azure AD) for authentication, developers often encounter challenges with the token configurations, particularly when it comes to embedding the App Registration Client ID into the Azure AD token. This post will guide you through how to effectively include your App Registration's Client ID in an Azure AD token, ensuring a smooth authentication process for your application.

Understanding the Problem

You might find yourself in a situation where, after logging into Azure AD, you receive an audience claim in the token that corresponds to the AAD Graph API (represented by the ID 00000002-0000-0000-c000-000000000000) instead of your specific API's Client ID. This discrepancy can lead to failed authentication attempts and issues when your API is accessed.

Example Configuration

In the sample configuration below, an API is set up with an Azure AD authentication scheme:

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The authentication configuration for the JWT bearer token is as follows:

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Step-by-Step Solution

To ensure that your API receives the correct Client ID in the Azure AD token, follow these steps:

1. Define a Scope in the API App Registration

The first step is to expose an API scope in your App Registration on the Azure portal. This defines what access the API allows. Here’s how to do it:

Navigate to the Azure portal.

Find your App Registration.

Go to the "Expose an API" section.

Add a new scope, for example: api://<client id>/Api.Read.

2. Use the Defined Scope in Swagger UI

Once you have defined the scope, configure your Swagger UI to use this new scope. Update the Swagger document configuration like so:

[[See Video to Reveal this Text or Code Snippet]]

3. Use the V2.0 Token and Authorization Endpoints

Make sure you're using the correct endpoints. Instead of the v1.0 endpoints, utilize the v2.0 token and authorization endpoints. This is essential for consistent behavior:

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Conclusion

By following these steps, you can seamlessly embed your App Registration Client ID into Azure AD tokens, thus ensuring that your ASP.NET Core API authentication works as expected. This setup improves security by making sure your tokens are intended for your specific API, rather than a generic audience.

For any developer working with Azure AD authentication in ASP.NET Core, understanding the importance of correctly setting up scopes, endpoints, and configurations is crucial for effective application security and user authentication.