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Set Document Encryption and Security

There are two types of passwords a PDF document can have:

  • User Password:
    Required to open and view the document. This password encrypts the document so that the contents are only viewable by those with the password.
  • Owner Password:(Advanced feature of Nitro PDF Pro. See Document Permissions.)Required to change document permissions, but not to view the document. The document is visible to all, but saving, printing, and/or copying may be restricted by the document owner.
While the user password secures the content of the document from view, the owner password secures what can be done with the content. A document may have both passwords.

Setting a User Password

  1. Choose File > Duplicate (Command+Shift+S) then in the new document choose File > Save (Command+S). Or use File > Save As (Command+Option+Shift+S).
  2. At the bottom of the Save dialog select an Encryption option. We recommend Strong.
  3. Enter a password in the Password field.
  4. Re-enter the same password in the Verify field.
  5. Click Save.
Whenever a password-protected PDF is opened, the user will be asked to enter the password you specified. You can test this by closing and opening your document.

Encryption Levels

The encryption level of a document determines its security and which other PDF applications can view it. There are three levels of encryption to choose from.

  • Weak: 40-bit RC-4 encryption level. Files with this encryption level can be viewed by users of any PDF viewer.
  • Strong: 128-bit AES encryption. Files with this encryption level can be viewed by users of Nitro PDF Pro v4.2 and later, Adobe Reader 7 and later, and Preview in macOS 10.5 and later.
  • Strongest, least compatible: 256-bit AES encryption. Files with this encryption level can be viewed with Nitro PDF Pro v5.3 and later, Adobe Reader 9 and later, Preview in macOS 10.7 and later.
As of version 6.2.1, Nitro PDF Pro supports working with files using 256-bit AESr6 encryption created with Adobe Acrobat X and later. Nitro PDF Pro cannot encrypt new files with this encryption level, but it can open and save files at this level. Users of Preview will not be able to view files at this encryption level.

Removing a User Password

  1. Choose File > Duplicate (Command+Shift+S) then in the new document choose File > Save (Command+S). Or use File > Save As (Command+Option+Shift+S).
  2. At the bottom of the Save dialog select "None" from the Encryption options.
  3. Click Save.

Setting an Owner Password

(Advanced feature of Nitro PDF Pro. See Document Permissions.)