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I use 1Password1 to store not only my own information, but also my sisters home Wi-Fi information.

Since she does not have a 1Password licence, I printed out the information for her to store in a safe place. Now, I was just thinking of using the printing dialog (under "Security Options...") to create a "password protected" PDF.

But what does that actually mean and how secure is it?

  • Does this encrypt the whole PDF?
  • What encryption is used?
  • Is it compatible with Windows and Ubuntu?

There does not2 seem to be a knowledge-base article on The info dialog in Finder merely says that the PDF is "Password Encrypted".

enter image description here

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up vote 2 down vote accepted

The last Time I checked a 128 bit RC4 encryption of the whole document was used. Also, compatability should be vested.

Here's a screenshot of the output of GuaPDF: enter image description here

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The download on the GuaPDF website was reported by Sophos AV to contain a virus "Slenfbot-E". Hence, I removed your link and cannot verify that 128-bit RC4 encryption is used. Do you mind creating a password protected PDF in Preview and checking it for yourself? – gentmatt Jan 12 '13 at 12:50
So here's a screenshot. I encrypted the PDF with checking all check boxes in the Security Options. You have to decide if you trust the output of this application. – cyphorious Jan 12 '13 at 17:21
Thanks for the update! I would always prefer first hand documentation by Apple about their software, but I'm willing trust this vendor for now ;) – gentmatt Jan 12 '13 at 18:02

Another method, guaranteeing 256-bit AES encryption, is to use Disk Utility to create an encrypted disk image of a folder containing the PDF, or just a text file for that matter. One cannot create a disk image of a file - it must be a folder.


  1. Create a folder, place file(s) to encrypt within
  2. Open Applications/Utilities/Disk
  3. Menu item File > New > Disk Image from Folder
  4. Choose folder to encrypt
  5. Click the Image button
  6. Select .dmg save location, read-only and 256-bit AES Encryption:

    enter image description here

  7. Click the Save button, then enter a password of your choosing or use the 'Password Assistant' which can generate a password for you of several types and lengths. You are also able to store this password in your Keychain.

Naturally, the encrypted .dmg file can only be opened on a Macintosh.

This technique is handy for encrypting anything that can be put in a folder.

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Thanks, I'm already aware of this nice and simple to use tool in Disk Utility. But I really want to secure the PDFs themselves because I cannot control if my sister's lax security practices will make her to simply copy the PDF from the encrypted disk image to somewhere else. – gentmatt Jan 13 '13 at 7:39

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