Private files are shared through signed download URLs. A link gets posted publicly. What limits the damage best?

Options

• ✓ Short expiry times, minutes rather than days, issued per request after an access check Correct
• ✗ Making the object key hard to guess
• ✗ Deleting the link from where it was posted
• ✗ Checking the user's session cookie at the storage service

Why

A signed URL is a bearer credential: anyone with it can use it until it expires, and the storage service never sees your sessions. Revoking one early usually means revoking the credentials that signed it, which breaks every URL they signed. So keep links short-lived and re-issue them on demand.

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