How to Implement OpenID Connect and OAuth 2.0 in Your Applications

You can use OpenID Connect and OAuth 2.0 in most new apps. These help keep your apps safe from things like people getting in without permission, losing data, or having accounts stolen. This is very important for places like Microsoft 365, Entra ID, and Google.

Apps without good authentication and authorization are at high risk.

Threat TypeDescriptionImpact/DetailsBroken Access ControlAttackers can do things or see data they should not.Over 90% of apps have this, which can cause leaks or let hackers in.Authentication FailuresLogin systems are weak or have mistakes.Attackers can pretend to be users or take over accounts.Injection AttacksBad input checks let attackers trick the app.This can let them steal data or control the whole system.Security MisconfigurationUses easy passwords or shows admin pages.Attackers can break in easily, especially in cloud apps.

These protocols may seem hard at first. But if you follow the right steps, you can use them and keep your apps safe.

Key Takeaways

• OAuth 2.0 lets your app ask for user data safely. It does not need passwords. OpenID Connect helps your app know who the user is. It adds login features.

• Use Authorization Code Flow with PKCE for browser apps. This keeps tokens safe. It lets users stay signed in longer. Do not use unsafe flows like Implicit Flow.

• Always register your app with the identity provider. Set exact redirect URIs using HTTPS. Keep your client secret private. This helps stop attacks.

• Store tokens in a safe way. Use HttpOnly cookies or server storage. Use short-lived access tokens. Check ID tokens carefully. This protects user accounts.

• Follow security best practices. Use PKCE. Check tokens. Do not use wildcards in redirect URIs. Rotate secrets. Test your setup often. This keeps your app safe.

OAuth 2.0 vs OpenID Connect

Protocol Roles

Before you use these protocols, you should know their main jobs. OAuth 2.0 and OpenID Connect help keep your app safe, but they do different things.

Tip: OAuth 2.0 lets your app ask for permission to use things, but OpenID Connect helps your app know who is using it.

Key Differences

There are some big differences between OAuth 2.0 and OpenID Connect. OAuth 2.0 is about letting apps use APIs or resources with access tokens. OpenID Connect builds on OAuth 2.0 and adds ID tokens. These help your app check who the user is.

You use OAuth 2.0 when your app needs to do things for a user. You use OpenID Connect when you want to know who the user is and let them log in.

How They Work Together

Most apps use both protocols together. OAuth 2.0 lets your app ask for access to resources. OpenID Connect adds a way to check who the user is. When you use both, users can sign in and your app can safely use APIs or data.

• OAuth 2.0 gives access tokens so your app can use APIs.

• OpenID Connect gives ID tokens so your app knows the user.

• The ID token has claims like the user’s name and email.

• You can use scopes like openid, profile, and email to get more info.

• Many apps use both for social login, single sign-on, and safe API access.

Note: Using both makes your app safer and easier for users.

Prerequisites and Setup

Requirements

You need to check if your app has what it needs. This helps you use OAuth 2.0 and OpenID Connect the right way.

1. Your app should send a POST request to the token endpoint. It must include things like the code, client ID, and client secret.

2. The server will reply with a JSON object. This object has an access token and token type.

3. You have to use the access token in the Authorization header. Use it when you call protected APIs.

4. If you want OpenID Connect, add the openid scope to your request. This gives you an ID token with user info.

5. The ID token is a JWT. It has three parts: header, payload, and signature. You use these to check if the token is real.

6. Always use TLS (HTTPS) to keep your data safe.

Here is a table that lists the main things you need:

Choosing Tools

There are many tools and libraries to help you. These make it easier to handle tokens, user sessions, and security.

Tip: Use official SDKs or libraries for your platform. They help you manage tokens and keep things safe.

App Registration

You need to register your app with the identity provider. This lets your app use OAuth 2.0 and OpenID Connect.

1. Register your app and set the redirect URI. It looks like https://yourapp.com/auth/callback.

2. Get your client ID and client secret. Keep the secret in a safe place.

3. Find the OpenID Connect metadata URL or get the issuer, authorization endpoint, token endpoint, and JWKS URI.

4. In the provider’s portal, add a new identity provider. Choose OpenID Connect.

5. Type in the provider name, metadata URL, client ID, and client secret.

6. Add scopes like openid, profile, and email.

7. Finish the setup and test your connection.

Note: Keep your client secret private. Use safe storage like environment variables or a key vault.

Implementation Steps

Select OAuth 2.0 Flow

You have to pick the right OAuth 2.0 flow for your app. The best flow depends on how your app works and where it runs.

• If you make a single-page app, use Authorization Code Flow with PKCE. This keeps your access token safe. The token does not show up in the browser. Your app gets a code first, then trades it for tokens. PKCE uses a code verifier and challenge for more safety. This stops attackers from stealing your code. This flow also lets users stay logged in longer with refresh tokens.

• For web apps that run on a server, use the regular Authorization Code Flow. Your server can keep secrets safe and handle tokens well.

• Do not use the Implicit Flow. It is not safe now. It shows tokens in the browser, so attackers can steal them.

Tip: Use Authorization Code Flow with PKCE for apps in browsers. This way is safer and lets users stay signed in longer.

Configure Redirect URIs

You need to set up redirect URIs the right way. The redirect URI is where users go after they log in. If you set this up wrong, attackers can steal tokens or trick people.

• Register each redirect URI exactly as it is in your app. Do not use wildcards or patterns like * in your URIs.

• Only use URIs you own. Never use a URI from another website.

• Always use HTTPS for redirect URIs to keep data safe.

• Use the state parameter in your requests. This helps stop attackers from taking over the login.

If you do not set up redirect URIs right, you could have these problems:

• Attackers might use open redirects to steal tokens.

• Wildcard patterns can let attackers use fake URIs.

• Users could get sent to fake sites.

• Tokens can leak if the redirect URI is not trusted.

Note: Always check your redirect URIs. Use exact matches and never use unknown websites.

Handle Tokens

After your app gets tokens, you must keep them safe. Access tokens and refresh tokens let your app use APIs and keep users logged in. If someone steals these tokens, they can take over accounts.

• Store tokens in safe places. For web apps, use HttpOnly cookies or keep tokens on the server. Do not use localStorage or sessionStorage. Attackers can steal tokens from there with XSS attacks.

• Use short-lived access tokens. This means a stolen token will not work for long.

• Use refresh tokens with rotation. Each time you use a refresh token, the server gives you a new one. If someone tries to use an old token, the server will block it.

• For OpenID Connect, always check the ID token. Make sure the issuer and audience are what you expect. Check the signature and expiration time. If you use a nonce, make sure it matches what you sent.

Security Tip: Never put tokens in URLs or browser storage. Always check tokens before using them.

Code Example

Here is a simple Python example. It shows how to trade an authorization code for tokens with OAuth 2.0. This uses the requests_oauthlib library.

from oauthlib.oauth2 import BackendApplicationClient
from requests_oauthlib import OAuth2Session

client_id = 'your_client_id'
client_secret = 'your_client_secret'
authorization_base_url = 'https://example.com/oauth/authorize'
token_url = 'https://example.com/oauth/token'
redirect_uri = 'https://yourapp.com/callback'

client = BackendApplicationClient(client_id=client_id)
oauth = OAuth2Session(client=client)

authorization_url, state = oauth.authorization_url(authorization_base_url)
print('Please go here and authorize:', authorization_url)

authorization_response = input('Enter the full callback URL: ')

token = oauth.fetch_token(token_url, authorization_response=authorization_response, client_secret=client_secret)

response = oauth.get('https://example.com/api/resource')
print(response.content)

This code does these things:

1. Sets up the OAuth2 session with your client ID.

2. Makes the authorization URL and asks the user to log in.

3. Waits for the user to paste the callback URL after login.

4. Trades the code for tokens.

5. Uses the access token to call a protected API.

Tip: Always keep your client secret safe. Never share it or put it in public code.

When you use OpenID Connect, you also get an ID token. You should check this token by looking at the issuer, audience, signature, and expiration. This helps make sure the token is real and not changed.

Remember: Check your OpenID Connect and OAuth 2.0 setup often. Use short-lived tokens, safe storage, and strong checks to keep your app and users safe.

OpenID Connect Integration

Google Example

You can link your app to Google with OpenID Connect. This lets people sign in using their Google account. It helps keep your app safe. Here is how you do it step by step:

1. Go to Google Cloud Console. Set up the OAuth consent screen. Add your app’s info. Pick scopes like email and profile.

2. Make OAuth client credentials. Choose your app type. Enter your redirect URI. Write down your client ID and secret.

3. Open your identity management system. Add Google as a provider. Type in the client ID and secret.

4. Let users log in with Google. Your app gets an authorization code at the redirect URI.

5. Trade the code for tokens. Send a POST request to Google’s token endpoint. You get an ID token and access token.

6. Use the ID token to get user info or connect to other services.

7. If you use AWS Cognito, call the GetId API with the ID token. Then use GetCredentialsForIdentity to get temporary credentials.

8. Use these credentials to reach AWS resources.

Tip: Always use HTTPS for redirect URIs. Keep your client secret safe.

You might see errors during setup. Sometimes, the token signing algorithm is not what your app needs. For example, Google may send an RS512 token, but your app wants RS256. Fix this by changing the algorithm in your identity provider settings. Other problems can be wrong metadata URLs, missing setup, or old cookies. You can fix these by checking your URLs, clearing your browser cache, and making sure your client secrets are right.

Microsoft Example

You can use OpenID Connect with Microsoft Entra ID. This lets people sign in with their Microsoft account. Here are the main steps:

• Set the issuer URL to your tenant’s metadata endpoint. Make sure it uses HTTPS and has a good certificate.

• Register your app in the Microsoft Entra ID portal. Get your client ID and secret. Set the redirect URL to your app’s callback path.

• Map group claims if you use on-premises Active Directory. Use attributes like sAMAccountName instead of default group IDs.

• Remember, Entra ID only sends up to 100 groups in claims. If you need more, use advanced settings like OAuth2.GroupsByUniqueId.

• Change scopes and claims with options like OAuth2.CustomScope if your app needs special permissions.

• Make sure your access control engine can reach Microsoft to get user info.

• Save your secret values when you register. You cannot get them again later.

• Think about your deployment setup. If you have more than one network card or special security needs, change your settings.

Note: Always check group claim limits. Use unique IDs for big organizations.

If you see errors, check your encryption algorithms. Microsoft Entra ID supports certain signing and encryption methods. Make sure your app matches these. If you use group claims, check that your mappings are right. Always save your secrets and test your login flow.

Other Providers

Many other identity providers work with OpenID Connect. You can follow similar steps to connect your app:

• Register your app with the provider. Get your client ID and secret.

• Set your redirect URI. Use HTTPS to keep things safe.

• Add the provider to your identity management system. Enter the client details.

• Pick the scopes you need. Only ask for what your app needs. This follows the rule of least privilege.

• Change consent screens. Use clear names and privacy policies so users know what they share.

• Store user consent in their profile. This stops asking them again and makes things easier.

• Let users review and take back consent anytime. This keeps them in control.

• Use incremental authorization. Ask for more permissions only when needed.

• If users say no to consent, turn off features that need those scopes.

Security Tip: Always check the provider’s docs for supported algorithms and claim formats.

If you have errors, check your metadata URLs and client credentials. Set your log level to debug for more details. Make sure your claim keys match what the provider sends. Clear your browser cache if you have login problems.

OpenID Connect makes it easy to add safe login to your app. You can use Google, Microsoft, or other providers. Always follow best practices for consent, scopes, and token handling. This keeps your users safe and your app working well.

Best Practices and Troubleshooting

Security Tips

You can keep your app safe by using good security steps. Here are the most important things to do:

1. Use PKCE for all OAuth clients. PKCE helps stop code injection and CSRF attacks.

2. Always pick the authorization code flow with PKCE. Do not use the implicit flow because it can leak tokens.

3. Make sure your authorization server works with PKCE. It should check the code_verifier when trading tokens.

4. Stop token replay by using sender-constrained tokens. These only work for the client that got them.

5. Use dynamic client registration and server metadata for new deployments.

6. Follow the newest security tips from RFCs. Change your setup if new threats appear.

7. Never put tokens in URLs or browser fragments.

8. Check your provider’s metadata for PKCE methods like S256.

Tip: Experts say PKCE is best for all new apps, even on phones. PKCE helps protect against new attacks.

Common Pitfalls

Many developers make the same mistakes with OAuth 2.0. You can avoid problems by watching out for these:

• Storing client secrets in plain text or in your code. Use environment variables or a secure vault instead.

• Not changing secrets often. Rotate them to lower risk.

• Not checking tokens. Always see if a token is real and not expired.

• Missing scope checks. Only let actions that match the scopes.

• Weak CSRF protection. Use state and nonce to stop replay attacks.

• Using wildcards in redirect URIs. Always use exact matches and HTTPS.

• Not logging or watching API use. Keep logs to find problems early.

• Storing tokens in unsafe places. Use safe storage and short expiration times.

• Skipping security audits. Test your app often to find and fix issues.

Note: Strong authentication, like multi-factor, gives users extra safety.

Debugging

If you have problems with OAuth 2.0, you can use special tools. The OAuth2 and OpenID Connect Debugger lets you test flows and see each step. You can enter your endpoints, client info, and scopes. Then you watch the authorization and token exchange process. This tool works with many providers like Azure Active Directory, Google, Okta, and AWS Cognito.

You can also use the debugger to look at and decode tokens. This helps you check if claims and signatures are right. The tool works locally with Docker and saves your settings for easy tests. Always check logs and error messages to find what went wrong.

Tip: Token introspection and decoding help you find and fix authentication problems.

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You now know how OAuth 2.0 and OpenID Connect work together to protect your app. You learned the difference between access tokens and ID tokens. PKCE is important because it helps keep things safe.

Keep learning by looking at advanced features like FAPI, JARM, and backchannel authentication.
Here are some important documents you can read to learn more:

Learning these protocols helps you make safer apps. You will also have more control over your app’s security.

FAQ

What is the difference between an access token and an ID token?

An access token lets your app use APIs. An ID token proves who you are. You use the access token for data. You use the ID token for login.

How do you keep your tokens safe?

You store tokens in secure places. Use HttpOnly cookies or keep them on your server. Never put tokens in URLs or browser storage. Always use HTTPS.

Why should you use PKCE in your app?

PKCE adds extra security. It stops attackers from stealing your login code. You use PKCE for all browser and mobile apps.

What should you do if login fails with OpenID Connect?

Check your client ID, secret, and redirect URI. Make sure you use the right scopes. Clear your browser cache. Look at error messages for clues.

Can you use OpenID Connect with more than one provider?

Yes, you can add many providers. Register your app with each one. Set up the client ID, secret, and redirect URI for every provider.