PDF Passwords Explained: The Two Kinds and When Each Works
Updated · by the My Gadgets team
A PDF can have two different passwords: an open password, which encrypts the file so nobody can read it without the password, and a permissions password, which only asks PDF readers to block printing, copying or editing. The first is real protection if the password is strong. The second is a polite request that many programs ignore. Knowing which one you have, or need, saves you from both false confidence and needless lockouts.
The two kinds of PDF password
| Open password (user password) | Permissions password (owner password) | |
|---|---|---|
| What you see | The reader asks for a password before showing anything | The file opens normally; some menu items are greyed out |
| What it does | Encrypts the content | Sets flags such as "no printing" or "no copying" |
| Who enforces it | Mathematics: without the password the content is unreadable | The PDF reader, if it chooses to respect the flags |
| How strong | As strong as the password, with modern encryption | Easy to remove with widely available tools |
| Use it for | Keeping a document confidential | Discouraging casual copying or editing |
A file can have both: an open password for the reader, plus permissions that limit what they can do once it's open.
How strong is an open password?
It depends on two things:
- The encryption the file uses. Current software (for example recent versions of Adobe Acrobat, Microsoft Word and LibreOffice) uses AES with 128- or 256-bit keys, which is effectively unbreakable by brute force. Very old PDFs may use 40-bit RC4, which is weak; if a file is decades old, assume it is.
- The password itself. Encryption doesn't help if the password can be guessed. Programs that "recover" PDF passwords work by trying millions of guesses, starting with common words, names, dates and short numbers. A date of birth or a phone number, which banks and employers often use for statements and payslips, can fall in minutes. Four random words, or 12 or more mixed characters, can't.
So a payslip protected with your date of birth keeps out a passer-by, not someone determined who knows when you were born.
Why do permissions passwords barely protect anything?
Because the content is still readable. To display the page at all, the reader must be able to decrypt it, so the "no copying" restriction is just a flag the reader is asked to obey. Mainstream readers honour it; many other programs don't, and anyone can screenshot or retype what they can see.
Use permissions to signal intent ("this is a final version; don't edit it"), not to protect secrets.
How do I add a password to a PDF?
In your browser, Protect PDF adds an open password with AES-256 encryption, and lets you switch off printing, copying and editing once the file is open. The PDF still opens in any reader after the password is typed, and the file never leaves your device. Or use software you probably already have:
- Microsoft Word: File → Save As, choose PDF, then Options and tick Encrypt the document with a password.
- LibreOffice: File → Export as PDF, then the Security tab, Set Passwords. You can set both an open password and permissions here.
- Mac Preview: File → Export, choose PDF and tick Encrypt, then enter a password.
- Adobe Acrobat (paid): Protect tools, with full control over both passwords and permissions.
Send the password by a different route from the file: a text message or a phone call, never in the same email.
And for storage only: a .mgenc file
Protect PDF has a second option for files you are keeping rather than sending: it seals the whole file into a .mgenc file (AES-256-GCM, with the key derived from your password using PBKDF2 and 150,000 iterations). No PDF reader opens it; Unlock PDF on this site turns it back into the original. That suits a copy in cloud storage or on a USB stick, not a document someone expects to open in their reader. For any file type, not only PDFs, Encrypt File does the same, with Decrypt File to open it. Either way the password can't be recovered: if you lose it, the file is gone.
How do I remove a password from my own PDF?
If you know the open password, Unlock PDF saves an unprotected copy: choose the file, type the password, download. It runs in your browser, so the statement or payslip isn't uploaded anywhere. Without any tool:
- Open the PDF in your browser (Chrome or Edge) or in your PDF reader, and enter the password.
- Choose Print, and as the printer choose Save as PDF (or Microsoft Print to PDF on Windows).
- Save. The new copy has no password.
On a Mac, Preview can also Export as PDF without the Encrypt option. Some readers refuse to print if a permissions password forbids it; in that case the file's owner needs to give you an unrestricted copy.
The other PDF tools on this site can't edit a protected PDF. If you open one in, say, Compress PDF or Merge PDF, they tell you so; unlock it first and they work on the copy. Unlock PDF removes a password only when you know it, and it leaves alone the printing and copying restrictions of a PDF that opens without one: those are its owner's to lift.
What if I've forgotten the password?
- Bank statements and payslips: the password is usually set by the sender, often from your date of birth, customer number or part of your ID number. The email that came with the file normally says which.
- Your own files: if you set a strong password and lost it, the encryption is doing its job; there's no back door. Look for an unprotected original instead.
- Someone else's file: ask the sender for the password or an unprotected copy. Breaking protection on a file you're not entitled to open may be illegal where you live.
Quick answers
Is a password-protected PDF safe to email? With a strong open password sent separately, yes for most purposes. With a date of birth as the password, it's protection against accidents, not against someone targeting you.
Why can I open a PDF but not print it? It has a permissions password that disallows printing. Ask the sender for an unrestricted copy if you need one.
Does a PDF password stop screenshots? No. Anything visible on screen can be photographed or captured.
Can I sign a password-protected PDF? Not until you save an unprotected copy with the steps above; then Sign PDF works on it.
What to do next
To send a PDF that only the right person can open, add a password with Protect PDF and send the password separately. To stop typing the password of your own statements every time, remove it with Unlock PDF. If you're sharing an ID or payslip, read how to share one safely first.