03 / WHAT PROTECT PDF D
What Protect PDF Does
This tool applies real AES-256 encryption to your PDF, using the PDF 2.0 standard revision 6. The encryption is performed by qpdf on our servers after you upload the file. The result is a document that cannot be opened without the correct user password.
You can also set permissions that control printing, copying, and modification. These are enforced by most PDF readers, but note that they are requests rather than absolute locks; software that ignores them exists. The open password, however, is real encryption.
04 / HOW TO USE
How to Use
Select a single PDF file up to 50 MB in size and no more than 500 pages. The file must be unencrypted; we refuse files that are already protected.
Choose a user password – this is required. Without one, the job is refused. You may also set an owner password to restrict permissions without blocking opening. If you leave the owner password empty, we generate a strong random one so that permissions cannot simply be lifted.
By default, printing is allowed, while copying and modification are off. You can change these options. Screen-reader accessibility is always allowed, regardless of your other settings.
Click to start the job. The page shows uploading, then queued, then running with a percentage. When it is done, download the protected file.
05 / WHAT HAPPENS TO YO
What Happens to Your File
Your uploaded PDF is scanned for malware before any processing begins. The file type is determined by reading the actual bytes, not the file name. If it is not a genuine PDF, it is rejected early.
The file is stored in private object storage. If you are not signed in, it is deleted after 1 hour. If you are signed in, it is deleted after 7 days.
After encryption, the tool verifies that the output is truly encrypted and cannot be opened without the password. If verification fails, the job errors out rather than giving you a file that only looks protected.
06 / LIMITATIONS AND ED
Limitations and Edge Cases
The tool works on one PDF at a time. If you need to protect multiple files, run them one by one.
Only PDFs are accepted; other file types are rejected even if renamed with a .pdf extension.
If your PDF is already password-protected, the tool will refuse it. Remove the existing protection first.
Remember that permission flags are not a digital rights management system. They are a standard that PDF readers are expected to honor, but a determined user may bypass them with specialized software.
07 / IF SOMETHING GOES
If Something Goes Wrong
If the job fails, the uploaded file is not processed, and you will not be offered a download. Common reasons include: the file exceeds 50 MB or 500 pages, the file is not a valid PDF, the file is already encrypted, or the user password was left empty.
Check those conditions and try again. There are no warning codes; the page simply indicates a failure. If the problem persists, consider compressing the PDF or splitting it into smaller parts, then try again.
FAQ
Common questions
Will encryption reduce PDF quality?
No. Encryption does not alter the content of the PDF. The visual quality and text remain exactly the same.
What is the maximum file size?
The file can be up to 50 MB and up to 500 pages. Larger or longer files are rejected.
Can I protect a PDF that is already encrypted?
No. The tool refuses already-protected PDFs. You must remove the existing password and protection first.
Does the tool work with scanned PDFs?
Yes, as long as the file is a valid PDF. Scanned PDFs are just images inside a PDF container, so they can be encrypted.
What happens to my file after I download it?
If you are not signed in, the file is deleted from our storage after 1 hour. If you are signed in, it is deleted after 7 days.