SSO with OIDC

🚀 The Core Concept: What OIDC + SSO Actually Do

OIDC (OpenID Connect) is the modern identity layer built on OAuth 2.0. SSO (Single Sign-On) is the user experience you get when multiple apps trust the same IdP.

The flow in one sentence:

Your app redirects the user to Okta → Okta authenticates → Okta sends back a signed token → your app trusts it and logs the user in.

This eliminates:

• Login forms

• Password storage

• Manual user ID entry

• Session management complexity

🔐 Why OIDC is the modern standard

Sources highlight that OIDC is winning because it’s lightweight, JSON‑based, mobile‑friendly, and easier than SAML . OIDC also provides:

• ID Token (JWT) → proves identity
• Access Token → access APIs
• Refresh Token → long-lived sessions
• UserInfo endpoint → fetch profile data

OIDC is now the default for enterprise SaaS and internal apps because it standardizes identity verification across Okta, Azure AD, Google Workspace, etc.

🧩 The Components You Work With

• Identity Provider (IdP) → Okta, Azure AD, Auth0

• Relying Party (RP) → your Java/Jakarta EE application

• ID Token → JWT containing claims like sub, email, name

• Authorization Code Flow → the recommended secure flow for web apps

🔄 The OIDC Authorization Code Flow (Step-by-Step)

1. User hits your app App sees no session → redirects to Okta /authorize.

2. Okta login page User enters credentials + MFA.

3. Okta redirects back Your app receives ?code=XYZ.

4. Your app exchanges the code POST to Okta /token endpoint → receives:

   • ID Token

   • Access Token

   • Refresh Token

5. Your app validates the ID Token Using Okta’s JWKS keys.

6. Your app creates its own session Usually a secure cookie.

7. User is logged in No password ever touches your app.

🏗️ What You Configure in Okta (OIDC App)

From Okta’s OIDC app setup guides :

🧱 What You Configure in Your Java App

You need:

• Issuer URL

• Client ID / Secret

• Redirect URI

• Token validation logic

• Session creation

🧪 Security Best Practices (from multiple sources)

• Use Authorization Code + PKCE for web apps and SPAs

• Validate tokens using JWKS

• Enforce strict redirect URI matching

• Never trust email as a unique identifier (use sub)

• Implement logout strategy (IdP + app session)

• Use SCIM for provisioning if you need automatic user lifecycle management

🧭 OIDC vs SAML (Quick Comparison)

OIDC is preferred for modern apps because it’s lightweight and works across browsers, mobile apps, and APIs.

🛠️ How SSO Fits In

SSO is simply the experience created when multiple apps trust the same IdP.

From SSO implementation guides: Once the user has an IdP session, all apps skip login and accept the existing session.

🧠 Putting It All Together

OIDC gives your app:

• A secure identity token

• A standardized login flow

• A way to trust Okta instead of storing passwords

• A foundation for SSO across all your apps

SSO gives your users:

• One login

• Seamless access

• Strong MFA

• Centralized security