What Is OIDC?
OIDC stands for OpenID Connect, a simple identity layer that works on top of the OAuth 2.0 protocol. It allows clients to verify the identity of the end-user based on the authentication performed by an authorization server. In other words, OIDC provides a way for you to ensure that a user is who they claim to be. It’s like having a virtual ID card that confirms a user’s identity.
OIDC has become a popular choice for authentication due to its robustness and flexibility. It is compatible with web, mobile, and JavaScript clients, making it a versatile choice for developers. Furthermore, OIDC is a standardized protocol, which means it is widely accepted and used around the globe.
Being a layer on top of OAuth 2.0, OIDC also inherits the security features of the protocol. It adds an identity layer on OAuth 2.0, providing additional information about the user. This makes OIDC a secure, comprehensive authentication solution for modern applications.
3 Core Components of OIDC Authentication
Client
In the context of OIDC, the client is the application that is requesting authentication. The client could be a web application, a mobile app, or even a JavaScript client. The client initiates the authentication request, redirecting the end-user to the OIDC provider for authentication.
Once the user successfully authenticates, they are redirected back to the client. The client then receives an identity token, which it can decode to extract user information. This information could include the user’s name, email address, or other details, depending on the scope of the request.
The client plays a crucial role in OIDC Authentication. It acts as the bridge between the end-user and the OIDC provider, facilitating secure authentication and ensuring that user data is handled correctly.
Identity Token
The identity token is a key component of OIDC Authentication. It’s a JSON Web Token (JWT) that contains information about the authenticated end-user. The OIDC provider issues this token after the user successfully authenticates.
An identity token typically contains three parts: a header, a payload, and a signature. The header contains metadata about the token, including the type of token and the algorithm used for signing. The payload contains claims, which are statements about the end-user and additional metadata. The signature is used to verify that the sender of the token is who they say they are and to ensure that the message wasn’t altered during transit.
Identity tokens provide a secure and standard way of conveying user information from the OIDC provider to the client. They ensure that the client can trust the user data it receives.
User Info Endpoint
The User Info Endpoint is a feature of the OIDC provider that returns claims about the authenticated end-user. The client can access this endpoint to retrieve user information once the user has authenticated.
The User Info Endpoint provides a way for the client to fetch additional user information that may not be included in the identity token. This could include profile information, email address, phone number, and more.
The User Info Endpoint plays a crucial role in enhancing the capabilities of OIDC Authentication. It provides a way for the client to retrieve rich, detailed user information, ensuring a comprehensive and personalized user experience.
OIDC Provider
The OIDC Provider (also known as the Authorization Server) is the entity that handles user authentication and issues identity tokens. It presents the end-user with an authentication interface, collects their credentials, and validates them.
Upon successful authentication, the OIDC Provider issues an identity token to the client. It also provides the User Info Endpoint, allowing the client to fetch additional user information.
In essence, the OIDC Provider is responsible for ensuring the security and integrity of the authentication process, protecting user data, and providing reliable user information to the client.
Setting Up OIDC Authentication
Choosing an OIDC Provider
The first step in setting up OIDC Authentication is selecting an OIDC Provider. The OIDC Provider is the service that verifies the user’s identity and delivers the information to the application. There are many providers available, such as Google, Microsoft, Okta, and Auth0. Each provider possesses different features, and the choice depends on the specific requirements of your application.
When selecting an OIDC Provider, there are several factors to consider. These include the provider’s reputation, security measures, pricing, and the support offered. For instance, if your application needs to support multiple platforms (like web, mobile, and desktop), you might want to choose a provider that supports these platforms. The provider’s documentation and community support are vital factors as well because they can significantly ease the setup process and future troubleshooting.
Registering the Application
After choosing an OIDC Provider, the next step is registering your application with them. Registration is a crucial step as it helps the provider identify your application and determine how it interacts with the provider’s service.
The steps for registering an application may vary depending on the provider, but generally, it involves visiting the provider’s developer console or dashboard and creating a new application. You’ll need to provide some basic information about your application, such as its name, logo, and description. Some providers might also ask for the type of application (web, mobile, or desktop) and the programming language it’s built with.
Once your application is registered, the provider will generate a Client ID and a Client Secret for your application. These credentials are used to authenticate your application when it communicates with the provider’s service. It’s crucial to keep these credentials secure and never expose them publicly.
Configuring Redirect URIs
The third step in setting up OIDC Authentication is configuring Redirect URIs. A Redirect URI is the location where the provider sends the user after they have authenticated. It’s essentially a callback URL that the provider uses to send the authentication response back to your application.
In the provider’s developer console or dashboard, you’ll need to add the URI of your application where you want the authentication response to be sent. This could be a specific page in your application where you handle the authentication response. It’s important to ensure that this URI is secure and only accessible by your application to prevent any potential security risks.
If your application uses multiple environments (like development, staging, and production), you might need to add multiple Redirect URIs. Each environment should have its own unique Redirect URI to ensure the proper functioning of the authentication flow in each environment.
Selecting Scopes
The last step in setting up OIDC Authentication is selecting scopes. Scopes are permissions that your application requests from the user. They define what information your application can access and what actions it can perform on behalf of the user.
When configuring your application in the provider’s developer console, you’ll need to specify the scopes your application requires. Typical scopes include “openid” (for basic profile information), “email” (to access the user’s email address), and “profile” (for additional profile information like name and picture).
The scopes you select should align with the functionality of your application. Requesting unnecessary scopes can lead to privacy concerns and may deter users from using your application. Therefore, it’s crucial to only request the minimum necessary scopes that your application needs to function correctly.
Implementing OIDC in an Application: Step by Step
OIDC Authentication is a powerful tool to enhance the security of your application. This section will guide you through the necessary steps to integrate OIDC in your application.
1. Integrating Libraries/SDKs
Libraries and SDKs are pre-written code that developers can use to simplify the coding process. In the context of OIDC, numerous libraries and SDKs are available that support its integration into applications. This greatly eases the process of adding OpenID Connect to your application.
When choosing a library or SDK for OIDC, you must consider the language of your application. There are libraries and SDKs for all popular programming languages. For instance, if you’re developing an application in Python, you might want to use pyoidc. On the other hand, if you’re using Node.js, openid-client would be a better fit.
After selecting the right library or SDK, you’ll need to install it into your application. Most libraries and SDKs are easily installable using package managers like npm or pip. Once installed, you’ll typically need to import the library or SDK in your application script to begin using it.
2. Building the Authentication Flow
OIDC uses an authentication flow known as the ‘Authorization Code Flow’. This flow involves a series of steps that ensure the secure authentication of the user.
The first step in this flow is the Authorization Request. This is where the client (your application) requests authorization from the user. The request is sent to the Authorization Server, specifying parameters like the client_id, redirect_uri, and scope. The scope parameter defines the level of access the client is requesting.
Once the user authorizes the request, the Authorization Server redirects the user back to the application with an Authorization Code. This code is a temporary credential representing the user’s authorization. It’s important to note that this code does not contain any user information.
The next step in the flow is the Token Request. The client sends the Authorization Code to the Authorization Server’s token endpoint and requests an ID Token. The Authorization Server verifies the Authorization Code and sends back an ID Token if the verification is successful.
3. Validating the ID Token
After receiving the ID Token, it’s crucial to validate it before extracting any user information. The ID Token is a JSON Web Token (JWT) that contains information about the user. However, before trusting this information, the client must verify the ID Token’s signature.
The first step in validating the ID Token is to decode it. This gives you three parts: the header, payload, and signature. The header contains the algorithm used to sign the token. The payload contains claims about the user, and the signature is used to verify the token.
Once the token is decoded, you can validate the signature. This involves using the public key of the Authorization Server (obtained during the discovery phase) and the algorithm specified in the header. If the validation is successful, you can trust the claims in the payload.
Apart from the signature, it’s also essential to validate the claims in the payload. You need to ensure that the issuer (iss) claim matches the issuer of the Authorization Server, the audience (aud) claim includes your client_id, and the expiration time (exp) claim has not passed.
4. Extracting User Information
After validating the ID Token, you can safely extract user information from it. The ID Token contains several standard claims about the user, such as the subject (sub), name, preferred username, email, and profile picture.
The subject (sub) claim is a unique identifier for the user. This identifier is consistent and never changes, making it useful for tracking user activity and sessions. The name, preferred username, and email claims provide personal information about the user that can be used to personalize their experience. The profile picture claim provides a URL to the user’s profile picture, which can also be used to enhance the user’s experience.
It’s important to note that the ID Token may contain other custom claims depending on your OIDC provider. You can extract these claims in the same way as the standard claims.
That’s it! We have covered the general steps involved in integrating OIDC into your application. Once you have followed these steps, you should have OIDC authentication up and running.
Conclusion
OIDC Authentication is an indispensable technology for modern applications aiming for robust, secure, and flexible user authentication. Built on top of the well-established OAuth 2.0 protocol, OIDC adds an identity layer that allows clients to verify end-user identity effectively. From web and mobile apps to JavaScript clients, OIDC offers unparalleled versatility, making it a go-to choice for developers across platforms.
Setting up OIDC Authentication involves several steps, from choosing a suitable OIDC Provider to registering your application and configuring key elements like Redirect URIs and scopes. Implementation, although intricate, can be significantly streamlined with the aid of libraries and SDKs tailored for various programming languages.
This practical guide aimed to provide an in-depth understanding of OIDC Authentication, from its core components to a step-by-step implementation guide. Whether you’re a seasoned developer looking to bolster your application’s security or a beginner just stepping into the realm of authentication technologies, OIDC offers a compelling, standardized solution that is both comprehensive and globally accepted.
