## Defense in Depth for Creator Platforms Authentication is the front door of your product. If auth breaks or leaks credentials, user trust is destroyed instantly. Modern web architectures must balance two competing goals: frictionless sign-in (e.g. one-click Google OAuth, WebAuthn Passkeys) and rigorous protection against CSRF, session fixation, and cross-origin leakage. ### 1. Strict Session Cookie Hygiene Never store JWTs or sensitive bearer tokens in `localStorage`. They are vulnerable to XSS extraction. Instead, leverage partitioned, HttpOnly, SameSite cookies: - **HttpOnly**: Completely blocks JavaScript access via `document.cookie`. - **SameSite=Lax**: Prevents ambient cookie transmission in third-party cross-site request contexts. - **Secure**: Restricts cookie transport strictly to HTTPS tunnels. ### 2. Dynamic Host Allowlisting & Proxy Trust Behind reverse proxies like Vercel or Cloudflare, origin validation must dynamically check incoming `x-forwarded-host` headers against trusted domain patterns while rejecting spoofed headers. With Better Auth, specifying `allowedHosts: ["*.vercel.app", "yourdomain.com"]` ensures preview branches receive automatic CSRF protection without manual reconfiguration. ### 3. Passkey Readiness Passkeys (FIDO2 / WebAuthn) replace vulnerable passwords with cryptographic public-key signatures. By eliminating shared secrets entirely, credential phishing is rendered mathematically impossible.