Add AES-256 password protection to any PDF. Control who can open, print, copy, or edit your documents.
Some documents shouldn't be freely accessible. Contracts with sensitive terms, financial reports, personal information, confidential business plans — these need protection before being shared.
Adding a password to a PDF encrypts it with AES-256 so only recipients who know the password can open it. You can also set permissions to prevent printing, copying, or editing even after the document is opened.
Add a password to your PDF document to restrict access
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Maximum file size: 50MB
PDF password protection encrypts the document content using AES-256 encryption, keyed to the password you set. Without the password, the file is unreadable — it opens as an encrypted document that can't be viewed. You can also set a separate permissions password that allows viewing but restricts specific operations like printing, text copying, or editing.
Use cases include:
Protecting a contract before sending it to a counterparty who shouldn't share it further.
Securing a financial report before distributing it to stakeholders.
Protecting personal documents (tax returns, identity documents) stored in cloud storage.
Restricting printing and copying on a proprietary document.
Protecting a confidential proposal before sending it to a potential client.
Protected PDFs can be shared with confidence — only recipients with the password can access the content.
Set your password, download the protected document.
Upload the PDF you want to protect.
Set a strong password. Optionally configure permissions restrictions (no printing, no copying, etc.).
Download the password-protected PDF. Share it with recipients and communicate the password through a separate, secure channel.
Upload, set password, download protected document. Share the password separately.
The uploaded PDF is processed to add an encryption dictionary to the document catalog.
A 256-bit key is derived from your password. All content streams are encrypted using this key.
The output PDF is a standard encrypted PDF that opens in all PDF viewers. Recipients enter the password to access the content.
PDF encryption uses AES-256 to encrypt document content streams.
A 256-bit encryption key is derived from your password using a key derivation function (PBKDF2 or similar). The key derivation process makes brute-force attacks computationally expensive.
Each content stream in the PDF (text, images, fonts) is encrypted using the derived key. The encryption dictionary in the document catalog specifies the algorithm and key parameters.
When a recipient opens the PDF and enters the correct password, their PDF viewer derives the same key and decrypts the content streams for display.
For documents that shouldn't be accessible without authorization, password protection is the appropriate security layer.
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Find answers to common questions about our PDF tools
Password protection encrypts the PDF so it can only be opened by someone who knows the password. Without the password, the file appears as an unreadable encrypted document. You can also set permissions restrictions that prevent printing, copying text, or editing even after the document is opened.
We use AES-256 encryption — the current industry standard for PDF protection. This is the same encryption used by banks and government agencies. A well-chosen password with AES-256 is effectively unbreakable.
Yes. You can set permissions restrictions (no printing, no copying, no editing) separately from the open password. This allows recipients to view the document but restricts what they can do with it.
A strong password is at least 12 characters, combines uppercase and lowercase letters, numbers, and symbols, and doesn't use dictionary words or personal information. A password like 'Contract#2024$Secure' is much stronger than 'password123'.
No. The document content is encrypted but not modified. When opened with the correct password, it looks and functions exactly as the original.
Yes. Use our Unlock PDF tool to remove the password when you no longer need the protection. You'll need to know the current password to remove it.
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