Password Protect PDF
Add a password to a PDF with AES-256 encryption, so it asks for that password every time it is opened.
How to password protect a PDF
- Choose the PDF you want to lock.
- Enter a password of at least 6 characters, then type it again to confirm.
- Press Protect this PDF.
- Wait for the check, download the protected copy and store the password somewhere safe.
Options
- Password
- The password needed to open the PDF. It must be at least 6 characters long. There is no upper limit set by Deckle.
- Confirm password
- Type the same password again. The button stays disabled until both fields match, and a mismatch is shown under the field as you type.
- Reset passwords
- Clears both fields. Undo keeps only one step, so earlier versions of the password are not held in memory.
What you get
- One PDF named after the original with "(protected)" added.
- The file is encrypted with AES-256. Opening it needs the password you entered.
- Pages, page sizes and text are kept. Only the file's encryption changes.
- The same password is set as the owner (permissions) password. Deckle does not set separate editing or printing restrictions.
- The Producer property is set to Deckle. Use Remove PDF metadata first if you want other properties gone before you lock the file.
Limits
- One PDF at a time.
- Passwords shorter than 6 characters are not accepted.
- A PDF that already has a password must be unlocked first. Use Unlock PDF, then protect the unlocked copy with the new password.
- Separate open and permissions passwords are not supported.
- A forgotten password cannot be recovered or reset by Deckle.
Check the result
Open the download in a new reader window: it should ask for a password, and the one you set should open all pages. Deckle runs the same test before the result appears, confirming that the file refuses an empty password and opens with yours.
Related guides
Questions
Which encryption does Deckle use?
AES-256, the strongest encryption the PDF standard defines. Deckle never writes the older RC4 encryption.
Is my password sent anywhere?
No. The PDF is encrypted in your browser and is not uploaded. The password is not stored, put in a link or written to the change record.
What if I forget the password?
The PDF cannot be opened without it, and Deckle has no copy. Keep the unprotected original until you have stored the password.
How long should the password be?
At least 6 characters is the minimum. A longer passphrase is much harder to guess than a short word.
Can I stop people printing or editing the PDF?
Not with this tool. It sets one password that is needed to open the file. It does not set permission restrictions.
Can I change the password on a PDF that already has one?
Yes, in two steps. Unlock it with the current password using Unlock PDF, then protect the unlocked copy with the new one.
Is the original PDF changed?
No. Deckle saves a new copy with "(protected)" in its name. The original stays unencrypted, so delete it yourself if it should not be kept.
Can I protect several PDFs at once?
No. Password protect PDF takes one file per run. Protect each file in turn, or merge them first with Merge PDFs and protect the combined file.
How should I share a protected PDF?
Send the password by a different route from the file, such as a phone call or a separate message, so one intercepted message does not open it.