The original title is: "Hardening a PHP Video Admin Panel With CSRF Double-Submit Cookies"

Short summary

A practical security walkthrough for protecting a PHP video admin panel against CSRF using the signed double-submit cookie pattern. The author explains why synchronizer tokens create session-locking and cache-invalidation problems at scale, and how double-submit cookies avoid server-side storage entirely. The critical detail is HMAC-signing the token to prevent cookie-injection bypasses, with production code for PHP 8.4 behind LiteSpeed and Cloudflare.

• •Synchronizer tokens serialize requests via session locks; double-submit cookies avoid server-side storage entirely
• •Naive double-submit is bypassable if an attacker can set cookies on your domain — HMAC signing fixes this
• •Production PHP 8.4 code shows token generation bound to session ID with HMAC-SHA256 signing

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