PHP SSO Integration

I’m tightening the security layer of my PHP website by moving all log-ins to a Single Sign-On model. The goal is straightforward: replace the current username/password flow with secure SSO through Google, Facebook, and LinkedIn.

Scope of work
• Build or adapt a clean PHP authentication module that handles OAuth2 flows for all three providers, stores the returned user data safely, and keeps sessions resilient against replay or token-swap attacks.
• Add graceful fallbacks and clear error handling so users know exactly what to do if any provider is unavailable.
• Wire the new flow into my existing user table, mapping provider IDs to local accounts without breaking legacy data.
• Document setup steps, API keys, callback URLs, and any server-side requirements so I can replicate the configuration in staging and production.

Acceptance criteria
• A user can click “Continue with Google/Facebook/LinkedIn,” complete the provider’s consent screen, and land back on my site fully authenticated.
• Access tokens are stored only server-side; refresh cycles are handled automatically.
• Logout clears the local session and revokes tokens with each provider.
• Clear, commented code plus a short README explain how to extend to additional SSO providers if needed.

If you have solid PHP experience with OAuth2, CSRF mitigation, and secure session management, let’s get started—I’m ready to provide repo access and provider credentials right away.