With the file open in Pages, Numbers, or Keynote, select File and then Set Password to choose and apply your password.

Adobe is working on another security-related add-on for Acrobat, LiveCycle Policy Server, that will allow document creators to set restrictions on who can read a PDF file, for how long and other ...

Adobe made a critical change to the algorithm used to password-protect PDF documents in Acrobat 9, making it much easier to recover a password and raising concern over the safety of documents ...