Short answer
Open Protect & Clean and add the PDF you want to protect. Set a strong open password, then save a new file.
Close the new PDF and open it again. Make sure it asks for the password and opens only when you enter the correct one.
Open password and owner password
An open password is needed to view the file. An owner password asks a PDF reader to limit actions such as editing or copying. Different readers may follow those limits differently, so do not rely on them as strong access control. Use an open password when only approved people should view the file.
Before you start
- Keep the unprotected source in an authorized safe location.
- Choose a long unique password and store it in a trusted password manager.
- Decide how the recipient will receive the password through a separate channel.
- Use a new filename so the protected and unprotected files cannot be confused.
Protect the copy
Add the PDF
Open Protect & Clean and select the local copy you are allowed to protect.
You should see: the correct filename and its current protection status.
Enter and confirm the password
Set the open password carefully. Add an owner password only when the intended reader and workflow use it.
You should see: both open-password fields accepted with no mismatch warning.
Create separate output
Choose a clear name and destination, then run the protection task.
You should see: a completed new file while the unprotected source remains unchanged.
Test before sending
Close the file, reopen it in another reader and enter the new open password.
You should see: a password prompt, followed by the full document after the correct password.
Verify access and content
- The file refuses to open without the new password.
- The stored password opens it in another reader.
- All expected pages, links and forms still work.
- The intended recipient can use the chosen password method.
Recovery and security limits
Osenpa PDF Tools can remove protection only when you know the current password. It does not recover an unknown password. Owner-password limits are stored as permission flags inside the PDF, and readers enforce those flags differently. Test the protected file in the recipient's reader. These limits are not the same as robust digital rights management. Password protection also does not remove metadata or visible sensitive content. Use the separate cleanup and redaction workflows those jobs require.
Osenpa PDF Tools
Add or remove a known PDF password locally and inspect a separate output.