Member files and paid content: cache hits still need authorization
Design delivery and authorization together, including expiry, sign-out and cached copies.
Contents of this article
Cacheable does not mean public
Many subscribers may download one file, but access must follow the business authorization rules. Identify where checks occur and what the chosen service supports; do not assume every plan provides signed URLs.
Do not erase security distinctions from cache keys
Ignoring query parameters to improve hit ratio may discard permission or version information. Separate tracking, content and authorization fields and test rule changes against users with different permissions.
Check what happens after a link expires
Test expired links, expired memberships, sign-out and revoked access. A server rule cannot recall a copy already downloaded to a device, so sensitive materials also require appropriate content and distribution controls.
Evaluate bulk-download behavior separately
Legitimate downloads still consume bandwidth. Size capacity from authorized users, file sizes and peaks, and confirm workload suitability before sharing a dynamic-API budget with large-file distribution.
References
OWASP REST Security Cheat Sheet