[Mihir-Rabari]

🚨 Severity: HIGH
💡 Vulnerability: In apps/auth-service/src/routes/codexRoutes.ts, a simple string comparison (clientSecret !== internalSecret) was used for verifying the internal service secret in the Codex authentication flow. This exposes the system to timing-based side-channel attacks, because string equality checks short-circuit on the first mismatched character.
🎯 Impact: An attacker could potentially discover the internal service secret byte-by-byte by carefully measuring the API response times of failed requests, leading to unauthorized access.
🔧 Fix: Replaced the direct string comparison with Node.js's crypto.timingSafeEqual(). Buffered both secrets and explicitly checked for length equality before the comparison to ensure constant-time execution independent of the input values and avoid TypeError on mismatched buffer lengths. Included an inline Sentinel comment.
✅ Verification: Verified using workspace wide pnpm test and specific cd apps/auth-service && pnpm test. Checked that formatting and linting pass for the specific modified service using pnpm format and pnpm lint --filter auth-service. The patch introduces no new regressions.

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PR created automatically by Jules for task 11433560090034243071 started by @Mihir-Rabari

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