Preparing for the Role of AI in Identity and Access Management

Understanding the Basics: OIDC and OAuth 2.0

OIDC and OAuth 2.0, eh? It's easy to get lost in the weeds, trust me. Let's break it down, so ya don't end up as confused as I was when I first tackled this stuff.

• OIDC, or OpenID Connect, it is built on top of OAuth 2.0, think of it like OAuth's smarter, more secure cousin, you know?
• OAuth 2.0? It's all about authorization– giving apps permission to access stuff. OIDC? Adds user identity to the mix. Big difference. (OAuth 2.0 and OpenID Connect overview - Okta Developer)
• So, what makes oidc, well oidc? It's all about ID Tokens, Access Tokens, and Refresh Tokens. These tokens are what makes it all work.

Let's get a bit more specific about those tokens:

• ID Token: This is the star of OIDC. It's a JSON Web Token (JWT) that contains verifiable information about the authenticated user – like their unique ID, who issued the token, who it's for, and when it expires. Think of it as a digital ID card for the user, proving they are who they say they are. Common bits of info you'll find in it are sub (subject, the user's ID), iss (issuer, who gave you the token), aud (audience, who the token is for), and exp (expiration time).
• Access Token: This is what OAuth 2.0 is primarily concerned with. It's a credential that grants the client application permission to access specific protected resources on behalf of the user. It's like a temporary key to a specific room, not the whole house.
• Refresh Token: This is a long-lived token that allows the client application to obtain new access tokens (and sometimes new ID tokens) when the current ones expire, without requiring the user to re-authenticate. It's how you keep sessions alive without constantly bugging the user.

Think about it: you're logging into a retail app using your Google account – that's OIDC in action. It's not just letting the app see some of your data, it's confirming who you are to the app, see?

Before we dive into the flows, let's meet the main characters:

• Resource Owner: This is usually you, the user, who owns the data.
• Client: This is the application that wants to access your data or verify your identity (e.g., a mobile app, a website).
• Authorization Server: This is the server that authenticates the Resource Owner and issues access tokens (and ID tokens for OIDC) after getting the Resource Owner's permission.
• Resource Server: This is the server that hosts the protected resources and accepts and validates access tokens.

Now, let's look at the different players involved.

Authorization Code Flow: The Recommended Approach

Alright, let's dive into the Authorization Code Flow. It's kinda like the VIP treatment for your data's security, ya know? It's the recommended approach for oidc, and there's a good reason why.

The Authorization Code Flow, in a nutshell, it goes like this:

• First, the user, they try to log in to an application, like, say, a healthcare portal.
• Then the application, it sends 'em over to the Authorization Server – kinda like a bouncer at a club, right?
• The user proves who they are to the 'bouncer' and says, "Yeah, I'm cool with this app seeing my stuff."
• The Authorization Server gives the app a special code, and sends the user back.
• The app then takes that code and quietly swaps it for the real goodies: Access Tokens, id Tokens, and maybe even a Refresh Token. This swap happens directly with the Authorization Server, usually through a secure, server-to-server communication. It's a much safer way to get those sensitive tokens.
• Finally, the app uses those tokens to grab the user's info, like medical records or financial data, ya know?

What's so great about this flow? Well, a few things. For starters, those tokens? They're not hanging out in the browser history, which is a plus. The sensitive tokens (Access Token, ID Token, Refresh Token) are obtained via a secure, server-to-server exchange, meaning they're not exposed directly in the browser's URL or history. Plus, the app authenticates itself when it grabs those tokens, stopping sneaky token theft. Refresh tokens also let you keep sessions alive longer, without bugging the user constantly. And, there's this thing called PKCE (Proof Key for Code Exchange) that makes it even more secure, especially for apps that can't keep secrets safe. Finally that authorization code is single use only, that is a big win!

So, when should you use this flow? If you're building a server-side web app, a mobile app, or anything where you can keep a secret safe, then this is the way to go. Especially, if you need those refresh tokens for long-lived sessions.

It is the recommended flow for a reason. Now, let's get into Implicit Flow and where things get a little less secure.

Implicit Flow: A Legacy Approach (and Why to Avoid It)

Implicit Flow, huh? It sounds kinda cool, like it's sneaking around, but trust me, it's not the flow you want to be using these days. Let's get into why.

So, the Implicit Flow, it went something like this:

• The user initiates the login.
• The client application, it redirects the user to the Authorization Server – that's where the "bouncer" lives, remember?
• User authenticates and says, "Yeah, this app is okay."
• Authorization Server redirects the user back to the client with tokens (ID Token, Access Token) in the URL fragment. Check out the stackoverflow answer I found, it shows the id_token is followed by # in the url OIDC : url differences in code flow and implicit flow.
• Client extracts those tokens from the URL.
• Finally, the client, it uses those tokens to access protected resources.

Crucially, Refresh Tokens are NOT typically issued in the Implicit Flow. This is a major limitation.

Here's where things get dicey. The Implicit Flow has some serious security flaws, like:

• Tokens hanging out in the browser history – not ideal.
• No client authentication, meaning anyone can grab those tokens if they're sneaky enough.
• No refresh tokens, so sessions are short-lived and annoying.
• Man-in-the-middle attacks are a VERY big concern.
• Tokens are exposed directly in the browser's URL fragment. This means they can be accessed by client-side JavaScript, potentially leaked through browser history, or even logged by web servers. This makes them vulnerable to XSS attacks and other browser-based exploits.

Truth? The inherent security risks make it unsuitable for modern apps. The Authorization Code Flow with PKCE is way more secure, especially for Single Page Applications (spas). OAuth 2.1? It's deprecating the Implicit Flow altogether so you should not be using it.

Next up, let's talk about when you might still consider using it, and I'll tell you, the list is SHORT.

Key Differences Summarized

Okay, so you're probably wondering what the real differences are, right? It's not just about the steps, but how it all plays out, so here's the skinny:

• Security is a big one: Authorization Code Flow? Way more secure. Implicit Flow? Kinda leaves your tokens flapping in the breeze.
• Token Handling: Code Flow exchanges tokens server-side, keeping 'em safe. Implicit Flow dumps 'em right in the browser, which is less than ideal, honestly. This exposure in the browser makes tokens vulnerable to various attacks.
• Refresh Tokens: Need long sessions? Code Flow's got your back with refresh tokens. Implicit Flow? Nope, you're SOL.

Now, let's look at application types, shall we? Next up...when Implicit Flow might still be a thing, even though you probably shouldn't.

Mitigating Risks and Best Practices

Okay, so you've picked a flow - now what? Don't just set it and forget it, folks.

• For the Authorization Code Flow, always, always use PKCE if you got a public client (like a mobile app or a single-page app). While PKCE is required for public clients, it's also a really good practice for confidential clients (server-side apps) to add an extra layer of security. Securely storing secrets matters, so ya need to do that.
• If you're stuck with the Implicit Flow, implement nonce validation; it will help stop replay attacks. This is an important OIDC practice for ID Tokens. However, the primary mitigation for the Implicit Flow's security issues is to avoid it entirely. If you absolutely must use it, implement strict CORS policies and handle tokens with extreme caution, though these are still less secure than the Authorization Code Flow. Plus, keep those tokens short lived, like real short Implicit Flow with OIDC - Auth0 documentation shows this.

Basically, keep an eye on those settings and configurations to keep everything secure.