Some documents should not be readable by whoever happens to find the email. Payslips, medical records, board papers, tax returns and client files all travel through systems you do not control, and encryption is the only thing that makes an intercepted copy useless.
Protect PDF applies AES-256 encryption — the same standard used for classified government data — and lets you set permission restrictions on printing, copying and editing for people who can open the file.
How to use Protect PDF
- 1Upload the PDF you need to secure.
- 2Set an open password. Use a long passphrase rather than a short complex string.
- 3Optionally set an owner password and restrict printing, copying or editing.
- 4Apply protection and download the encrypted file.
- 5Send the password to the recipient through a different channel from the document itself.
Choosing a password that is worth having
AES-256 is unbreakable by brute force; your password is not. A four-word passphrase such as 'harbour-lantern-copper-tuesday' has far more real strength than 'P@ss1234' and is easier to relay over the phone. Never reuse a password across clients or documents.
Send the password separately
Emailing an encrypted file and its password in the same message defeats the entire exercise. Send the document by email and the passphrase by phone call or message. This is also what most data-protection guidance requires.
Permissions are weaker than encryption
The open password is real cryptography. Permission flags are honoured by well-behaved readers but are not enforced by mathematics — treat them as a clear signal of intent rather than a guarantee.
Supported formats, limits and things to know
- There is no recovery: if the password is lost, the document cannot be opened by anyone, including us.
- Encrypted files cannot be processed by most other tools until unlocked.
- PDF/A archival format prohibits encryption, so protect and archive are mutually exclusive.
- Encryption is applied on our secure Premium servers.
Protect PDF — frequently asked questions
How strong is the encryption?
AES-256, the current industry and government standard. Its practical strength depends entirely on the strength of the password you choose.
What happens if I forget the password?
The document becomes permanently unreadable. There is no back door and we cannot recover it — store the passphrase in a password manager.
What is the difference between the open and owner passwords?
The open password is required to view the file at all. The owner password controls whether a viewer may print, copy or edit it.
Can I still merge or compress a protected file?
Not while it is encrypted. Do those operations first, then protect the finished document — or unlock, process and re-protect.
Should I email the password with the file?
No. Send them through separate channels; otherwise anyone who intercepts the email has both.