Protect PDF with Password
Lock a PDF with AES-256 and set print and copy permissions. Runs in your browser.
About this protect pdf with password
This tool password-protects a PDF with AES-256 encryption, so only people who know the password can open it. You can also limit printing, copying and editing. It works in your browser, and neither the file nor the password is uploaded.
That last part matters more than it sounds. Most online tools ask you to send a confidential file, plus the password meant to protect it, to someone else's server. Here the encryption runs on your own device with qpdf, a long-standing open-source PDF library, compiled to WebAssembly.
Use it for payslips, tax returns, contracts, medical reports and anything else you're about to email or upload to shared storage.
Features
AES-256 by default
Files are encrypted with AES-256 using the method defined in PDF 2.0 (ISO 32000-2, security handler revision 6). AES-128 is offered for very old readers.
Open password and permissions password
The open password is needed to view the file. The optional permissions password (often called the owner password) controls who can change the restrictions later.
Six permission settings
Printing (allowed, low quality only, or blocked), copying text and images, editing content, comments, form filling, and inserting, rotating or deleting pages.
Restrictions without an open password
Untick Require a password to open if anyone may read the file but you'd rather they didn't print or copy it. A permissions password is then required.
Strength hint and confirm field
A local strength check estimates how long your password would survive offline guessing, with a tip when it's weak. Typing it twice catches typos before they lock you out.
Checked before download
After encrypting, the tool reopens the new file with your password and reads back the encryption method and restrictions, so you know it worked.
How to use the protect pdf with password
- 1Choose a PDF.
- 2Type a password twice and choose what readers may print, copy or edit.
- 3Click Protect PDF and download the encrypted file.
When to use it
Emailing personal documents
Send a salary slip or bank statement as a protected PDF, and share the password by phone or a different chat app, never in the same email.
Client deliverables
Lock a report so the client can read and print it, but can't edit it or lift whole paragraphs without asking. Add a watermark first if you also want the pages visibly marked.
Exam papers and drafts
Share question papers or draft contracts ahead of time and send the password only when it's needed.
Archives in cloud storage
Encrypt scanned IDs and certificates before they sit in a shared drive or a backup. Merge related files into one PDF first so you only manage one password.
Owner password vs user password: what's the difference?
A PDF can carry two passwords. The user password, shown here as the open password, encrypts the file; without it, nobody can see the content. The owner password, shown here as the permissions password, grants full rights to change the restrictions.
If you leave the permissions password empty, the tool creates a random 48-character one and doesn't keep it. Restrictions then can't be lifted in a normal PDF editor, which is usually what you want. Either password opens the document.
AES-256 vs AES-128 for PDFs
Both are strong ciphers. The real difference is compatibility. AES-128 arrived with PDF 1.6 and works in practically every reader made in the last 20 years. AES-256 revision 6 is the PDF 2.0 standard and works in readers from about 2010 onwards, which includes all current desktop, browser and phone viewers.
Choose AES-128 only if someone must open the file in a very old program. It also limits passwords to 32 basic Latin characters, while AES-256 accepts up to 127 bytes of any script, including Bengali.
Avoid tools that still offer RC4. It's an older stream cipher with known weaknesses, and PDF 2.0 deprecates it.
Can a password-protected PDF be cracked?
Not the encryption itself. AES-256 has no known practical attack. What attackers do is guess passwords, and PDF password checks are cheap enough that a graphics card can try a very large number of guesses per second.
So the password is the weak point. An 8-character password made of a word and a year falls quickly. Four or five unrelated words, or 14 or more random characters, puts guessing out of reach. A password generator makes this painless.
What permissions can and can't do
Print, copy and edit restrictions are flags inside the file. Mainstream readers respect them, but enforcement is up to the app, not the math. Someone determined can open the file in software that ignores the flags. Treat restrictions as a polite fence, and rely on the open password for anything truly private.
Screen-reader access is always left on, so blind and low-vision readers can still hear the text.
Why use Mavros
| Mavros | Typical upload sites | |
|---|---|---|
| Where the file and password go | Stay in your browser | Uploaded to a server |
| Encryption | AES-256 (PDF 2.0) or AES-128 | Often AES-128, sometimes unstated |
| Permissions | Print, copy, edit, comments, forms, pages | Basic or paid-only |
| Separate permissions password | Yes, or a random one | Sometimes |
| Result verified | Reopened and checked before download | Not shown |
Tips
- Never send the password in the same email as the file. Use a call, SMS or a different app.
- Store the password in a password manager. There's no reset link for a PDF.
- Check a password with the password strength checker if you want a fuller breakdown of why it's weak.
- To change a password later, remove the current password and protect the file again.
- Protect after your last edit. Compress, sign and merge first, then encrypt.
Questions
How do I password protect a PDF for free?
Open the PDF here, type a password twice and click Protect PDF. Download the encrypted file. From then on every PDF reader asks for that password before showing the pages.
Is it safe to protect a PDF online?
Here it is, because nothing is uploaded. The encryption runs in your browser, so neither the document nor the password reaches any server, including ours.
What happens if I forget the password?
The file can't be opened. AES-256 has no back door and no reset, and no one can recover the password for you. Keep an unprotected original somewhere safe, or store the password in a manager.
Can I stop people from printing or copying my PDF?
Yes, with the permission settings. Mainstream readers will block those actions. Some apps ignore the flags, so don't rely on them alone for secrets.
Will the protected PDF open on phones and Macs?
Yes. Current browsers, phone PDF viewers and desktop readers all support AES-256. Only software from before about 2010 needs AES-128.
Does encryption make the file bigger?
Barely. Encryption adds a few hundred bytes plus a small amount per object. A 2 MB PDF stays about 2 MB.
Can I use a Bengali or non-English password?
Yes, with AES-256. It accepts any Unicode characters up to 127 bytes. AES-128 only allows basic Latin letters, digits and symbols, so the tool tells you if a password won't fit.
Can I protect several PDFs with one password?
Protect them one by one with the same password, or merge them into a single PDF first and protect that.