External Identity Providers in ASP.NET Core

External Identity Providers in ASP.NET Core

In this article, I will discuss External Identity Providers in ASP.NET Core Identity. Please read our previous article discussing Role-Based Claims Authorization in ASP.NET Core Identity. At the end of this article, you will understand the following pointers:

  1. What are External Identity Providers in ASP.NET Core Identity?
  2. Different External Identity Providers in ASP.NET Core Identity
  3. Why External Identity Providers in ASP.NET Core?
  4. How Do External Identity Providers Work in ASP.NET Core Identity?
  5. What is OAuth 2.0?
  6. What is OpenID Connect?
  7. Advantages and Disadvantages of External Identity Providers in ASP.NET Core Identity
  8. What are External Identity Providers in ASP.NET Core Identity?
What are External Identity Providers?

External Identity Providers in ASP.NET Core Identity are services that enable users to authenticate with a web application using their existing identity from a third-party service. In this case, the user’s identity and authentication are handled outside the application. In the context of ASP.NET Core Identity, these external providers can include popular social media platforms like Facebook, Google, Twitter, Microsoft accounts, etc.

Different External Identity Providers in ASP.NET Core Identity

ASP.NET Core Identity supports integration with various external identity providers, allowing users to log in using their existing credentials from these providers. Each external identity provider has its unique features and setup requirements. Here’s a look at some of the popular external identity providers you can integrate with ASP.NET Core Identity:

  • Widely used and recognized.
  • Requires setting up OAuth 2.0 credentials in the Google API Console.
  • ASP.NET Core provides the Microsoft.AspNetCore.Authentication.Google package for integration.
  • Popular social media platform with a vast user base.
  • Requires creating a Facebook App and obtaining App ID and App Secret.
  • The Microsoft.AspNetCore.Authentication.Facebook package is used for integration.
  • Useful for applications targeting social media users.
  • Requires creating a Twitter Developer account and an application to get API keys.
  • Integration is achieved using the Microsoft.AspNetCore.Authentication.Twitter package.
Microsoft Account:
  • Ideal for services targeting Windows users or services within the Microsoft ecosystem.
  • Requires registration on the Microsoft identity platform to obtain credentials.
  • Implemented using the Microsoft.AspNetCore.Authentication.MicrosoftAccount package.
  • Beneficial for professional networking services.
  • Requires creating a LinkedIn application to obtain client credentials.
  • Custom implementation might be necessary as there’s no dedicated package from Microsoft.
  • Suitable for services targeting developers.
  • Requires creating a GitHub OAuth application.
  • Integration can be done using the Microsoft.AspNetCore.Authentication.GitHub package.
  • Good for e-commerce or services integrated with Amazon’s ecosystem.
  • Requires setting up an Amazon Developer account and creating a security profile.
  • Custom implementation is typically required for Amazon integration.

Note: Asp.net core has built-in support for integrating these external authentication providers. Integrating these external authentication providers follows a similar pattern. If we understand how to integrate one of the external authentication providers, implementing others is not that different.

Why External Identity Providers in ASP.NET Core?

Users usually register with our application by providing their email, username, and password. We then use this local username and password to authenticate who the user is and sign him/her into our application. However, we do not have to always rely on a local username and password registered with our application.

Most people these days have accounts already created with third-party applications like Microsoft, Google, Facebook, Twitter, etc. Why do these users have to create yet another account with our application? It’s not a great user experience to ask the user to create another user account to log in to our application. We want to reuse their existing user account with Facebook, Google, Microsoft, Twitter, etc.

We trust these third-party applications and use them to authenticate and identify who the user is. For this reason, these third-party applications are commonly called trusted identity providers. To be more accurate, we call them trusted external identity providers, as these third-party applications are external to our own application.

Allowing users to reuse their existing accounts to log into our application benefits end users from having to remember yet another username and password. It also benefits us as application developers as we no longer have to store and maintain highly sensitive information such as the username and password in our application database. It is now the responsibility of the external authentication provider, such as Facebook or Google for example.

How Do External Identity Providers Work in ASP.NET Core Identity?

External Identity Providers in ASP.NET Core Identity are used to enable authentication with external services like Google, Facebook, Twitter, or Microsoft. This system allows users to log in using their existing credentials from these services, streamlining the login process and enhancing user experience. Here’s how it generally works:

Setup and Configuration:
  • First, the application must be configured to use ASP.NET Core Identity, which involves setting up the Identity framework in the service container.
  • Then, you register your application with external providers (like Google, Facebook, etc.) to obtain a client ID and client secret.
  • In your ASP.NET Core application, you configure the authentication middleware to use the information (client ID and client secret) provided by these external providers.
Authentication Flow:
  • Users are redirected to the external service’s login page when they choose to log in using an external provider.
  • After the user enters their credentials on the external service’s page, the service authenticates the user and redirects them back to your application, typically with an authorization code.
  • Your application then exchanges this authorization code for an access token with the external service.
  • The access token can be used to fetch additional user information from the external service, like the user’s email or profile picture.
Integrating with ASP.NET Core Identity:
  • ASP.NET Core Identity then checks if a user with the provided information (like email) already exists in its system.
  • If the user exists, they are logged in; if not, a new user account can be created automatically or after additional information is provided, depending on the application’s setup.
Security and Session Management:
  • Security measures such as validating the authenticity of information received from external providers and managing session tokens are handled by ASP.NET Core Identity.
  • It ensures that the user’s identity is maintained securely throughout their session.
Customization and Extension:
  • Developers can customize the process by adding extra steps in the user registration process or handling different types of user information.
  • It’s also possible to integrate multiple external providers, giving users a choice of which service to use for authentication.

For example, if a user wants to use his/her Google account to sign in to our application, they click the Google button.

External Identity Providers in ASP.NET Core Identity

Our application then redirects the user to the Google sign-in page. Here, the user provides his/her Google login credentials.

External Identity Providers in ASP.NET Core

Upon a successful login, google will send the user back to our application, and a pre-configured callback function is executed. The code in this callback function checks the identity received from the external identity provider and sign-in that user into our application.

To use an external identity provider like Google, we have to first register our application with Google. Upon successful registration, we will be provided with Client ID and Client Secret, which we need to use Google authentication.

What is OAuth 2.0?

OAuth 2.0 is an open standard for access delegation, commonly used for internet users to grant websites or applications access to their information on other websites without giving them passwords. It’s widely adopted for its simplicity and effectiveness in managing access permissions. Here’s a breakdown of how OAuth 2.0 works and its key components:

  • Resource Owner: Typically, the user who owns the data or has the right to grant access to it.
  • Resource Server: The server hosts the user data.
  • Client: The application seeking access to the user’s data on the resource server.
  • Authorization Server: The server that authenticates the resource owner and issues access tokens to the client after successful authorization.
  • Access Token: A token granted to the client by the authorization server, allowing access to the user’s data on the resource server. This token defines the scope, duration, and other access attributes.
  • Refresh Token: Optionally, obtain a new access token when the original expires.
  • Authorization Request: The client requests authorization from the resource owner (server hosting the user data) to access their resources.
  • Authorization Grant: If the resource owner (server hosting the user data) consents, an authorization grant type is chosen based on the application type and security requirements.
  • Access Token Request: The client requests an access token from the authorization server using the authorization grant.
  • Access Token Response: The authorization server authenticates the client, validates the authorization grant and issues an access token.
Grant Types:
  • Authorization Code: Used with clients to securely maintain a client secret.
  • Implicit: Used by mobile apps or web applications where the client’s secret cannot be securely stored.
  • Resource Owner Password Credentials: Directly uses the resource owner’s credentials to obtain an access token.
  • Client Credentials: Used for service-to-service communication where the client is also the resource owner.
Use Case:
  • A common scenario is logging into a service using a social media account. When a user logs in, the service uses OAuth 2.0 to obtain permission to access the user’s details from the social media platform without getting the user’s password.
  • OAuth 2.0 relies on SSL/TLS to secure the data exchange, making it suitable for sensitive data. It also allows for fine-grained access control.
What is OpenID Connect?

OpenID Connect is an authentication protocol built on top of OAuth 2.0, which itself is a framework for authorization. OpenID Connect provides a way for clients (such as web applications) to verify the identity of an end-user based on the authentication performed by an Authorization Server and obtain basic profile information about the end-user. Here’s an overview of how OpenID Connect works and its main components:

Protocol Basis (OAuth 2.0):

OpenID Connect extends OAuth 2.0. OAuth 2.0 is primarily about granting access tokens for accessing resources, while OpenID Connect is about authenticating users.

Roles in OpenID Connect:
  • End-User: The user who is being authenticated.
  • Client: The application (like a web app or mobile app) wants to verify the end-user’s identity.
  • Authorization Server (OpenID Provider): The server authenticates the end-user and issues ID and access tokens.
ID Token:
  • Unlike OAuth 2.0, OpenID Connect introduces an ID token, which is a JWT (JSON Web Token). This ID token is proof of authentication to the client and contains a standard set of claims (information) about the authenticated user.
Authentication Flow:
  • The client redirects the end-user to the Authorization Server.
  • The end-user authenticates (logs in) with the Authorization Server.
  • Upon successful authentication, the Authorization Server issues an ID token and, typically, an access token to the client.
  • The client can decode the ID token to obtain user information and use the access token to access protected resources.
Standard Claims:
  • The ID token contains standard claims or assertions about the authenticated user, such as the user’s identifier (sub), the issuer identifier (iss), and the time the authentication occurred (auth_time).
Scopes and Claims:
  • During the authentication request, the client can request specific scopes and claims. Scopes specify what access privileges are being requested (like profile, email), and claims are information about the user (like name, email).
Security Features:
  • OpenID Connect includes features to improve security, such as nonce parameters to prevent replay attacks and the option of using PKCE (Proof Key for Code Exchange) for mobile and public clients.
Discovery and Dynamic Registration:
  • OpenID Connect supports the discovery and dynamic registration of clients, which simplifies the integration of different OpenID providers and clients.
Use Cases:
  • OpenID Connect is used in single sign-on (SSO) scenarios, where a user logs in once and gains access to multiple applications.
Advantages and Disadvantages of External Identity Providers in ASP.NET Core Identity

Using external identity providers in ASP.NET Core Identity comes with its own set of advantages and disadvantages. Let’s explore these:

Advantages of External Identity Providers in ASP.NET Core Application
  • Enhanced Security: External identity providers often have robust security measures, such as two-factor authentication and regular security updates. This can reduce the risk of security breaches.
  • Ease of Use for Users: Users can log in using credentials from a provider they already trust and use regularly, like Google or Facebook, making the process more convenient.
  • Reduced Development Time: Using external providers can offload the complexity of managing user authentication. This simplifies the development process and reduces the time spent implementing authentication mechanisms.
  • Scalability: External providers can handle many authentication requests, ensuring your application scales effectively without additional infrastructure.
  • Compliance and Standards: Many external providers comply with various international standards and regulations, which can be beneficial if your application needs to meet specific compliance requirements.
  • Mobile App Integration: If your ASP.NET Core application has a mobile app counterpart, using external identity providers can provide a unified authentication experience across platforms.
Disadvantages of External Identity Providers in ASP.NET Core Application
  • Dependence on Third-Party Services: Relying on external providers means your authentication process depends on their service availability and performance.
  • Limited Customization: The authentication process and user data management are subject to the limitations and constraints of the external provider, which might not align perfectly with your specific requirements.
  • Privacy Concerns: There might be concerns about user data privacy, as a third party manages data. It’s crucial to understand how user data is handled.
  • Integration Complexity: Integrating multiple external providers can add complexity to your application, especially when handling different data formats and authentication flows.

In the next article, I will discuss How to Create Google OAuth Credentials. In this article, I explain External Identity Providers in ASP.NET Core Identity. I hope you enjoy this article, External Identity Providers in ASP.NET Core Identity.

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