How do I password-protect a PDF and limit what readers can do?
Upload the PDF to Sealique, set an open password or a permissions password, tick what readers may do, and download the AES-256 encrypted copy from your browser.
A payslip sent by e-mail, a report for a closed group, a price list that must not be copied into a competitor's spreadsheet: password protection keeps a PDF closed to anyone without the password and limits what those who open it can do with it.
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Key facts
- Protect PDF on Sealique encrypts a PDF with AES-256 (the strongest standard PDF encryption), included with an account.
- An open password is needed to read the file; a permissions password controls printing, copying, annotating and editing without blocking reading.
- You choose what readers may do: print, copy text, add comments and fill forms, or change the document.
- The encrypted file is kept with the job for download; your library keeps the unprotected original so you can still work on it.
- Encryption hides content from people without the password; a PAdES digital signature proves the content was not changed. They solve different problems.
How does PDF encryption work?
The file's streams and strings are encrypted with a key derived from the password using the AES-256 scheme of PDF 2.0 (revision 6). A reader with the open password decrypts the content; the permission flags inside the file tell viewers whether to allow printing, copying text, commenting and filling forms, or changing the document, and those flags can only be changed with the permissions password.
Permissions are enforced by well-behaved viewers; the open password is the only hard barrier. For content that must never leave the file, use Redact PDF instead.
Protect after signing
The PAdES digital signature seals the content; encrypting afterwards wraps that sealed content in a password. Verification online still works once the file is opened with the password, and the verification record itself never contains the document.
Protect PDF, step by step
Open Protect PDF
Sign in, open PDF tools and choose Protect PDF.
Choose the PDF
Drop a PDF of up to 50 MB or pick one from your library.
Set the passwords and permissions
Type an open password (required to read), a permissions password (required to change the restrictions), or both, and tick what readers may do.
Download the protected copy
Press Protect and download the encrypted PDF from the job page. Share the password separately from the file.
Protect PDF is included with a Sealique account; the processing happens in your browser and on our servers, nothing is shared with third parties.
What Protect PDF includes
- AES-256 encryption
- Open password and permissions password
- Allow or block printing, copying, annotating and editing
- Encrypted copy ready to download
- Original stays in your library
- Works from a phone or a computer
Questions people ask
What is the difference between the two passwords?
The open password is needed to read the PDF at all; the permissions password lets a reader open it freely but is required to lift the restrictions.
Set only a permissions password to publish a file anyone can read but nobody can print or copy.
Which encryption is used?
AES-256, revision 6 of the PDF standard, which every current viewer opens and which cannot be brute-forced in practice with a good password.
Can I still edit or sign the protected file on Sealique?
Work on the unprotected original in your library; protect the final version last. Signing happens before protection, and anyone verifying the signature needs the open password to read the file.
Is a password the same as a signature?
No. A password keeps people out; a PAdES digital signature proves who approved the document and that it was not changed, verifiable online by its verification ID or QR code.
Does it cost anything?
No. It is included with a Sealique account: no card, no watermark, no daily limit.