An employee leaves. The contract PDF they had encrypted access to is still useful to the rest of the team — but you'd rather they couldn't open it any more. PDFs aren't natively revocable, but you can simulate revocation with three tactics.
Rotate the password
Unlock the file with the original password and re-encrypt it with a new one. Distribute the new password to everyone still authorised. The departed employee's copy still opens with the old password — but only if they kept the old file.
This is the most common 'revoke' move. It doesn't reach copies already saved elsewhere, but it stops them being re-fetched from your shared drives.
Expire the link
If you shared via a link (Dropbox, Google Drive, secure-send service), expire or delete the link in the provider's UI. New attempts to fetch the file fail; existing downloaded copies are unaffected.
Link-based sharing is more revocable than email-based sharing — which is one reason regulated industries prefer it.
Accept what you can't undo
A PDF that's been emailed, downloaded and saved elsewhere is gone — you can't reach into someone's machine. For documents where this matters, use a DRM-protected viewer (Vitrium, Locklizard) that calls home to check authorisation every time the file opens. That's a different product class and only worth it for genuinely high-stakes content.
For everyday confidential PDFs, password rotation + link expiry + a record of who had access is good enough.
FAQ
Can I delete a PDF from someone's machine remotely?
Not unless they're on a device you manage (MDM/EMM). On a personal machine, you can't reach it.
What if the recipient says they deleted the file?
You have their word. For sensitive matter, get the assurance in writing and document the date.
Should I add a watermark with the recipient's name?
Yes for high-sensitivity material. Watermarks discourage forwarding and identify the leak source if a copy turns up elsewhere.
Does Flint offer expiring links?
Flint focuses on the file itself — encryption, signing, redaction. For expiring links, pair Flint with a secure-share service like Tresorit or your existing cloud provider.
Revocation is mostly limiting future access. Rotate the password and tighten the share.