PDF security can be compared with home security. Just as you lock your doors to prevent others from entering your house without permission, you may use the various security features to “lock” PDF documents. For example, you can add passwords to restrict users from opening a PDF document, or they can prevent users from printing or editing a document.
A PDF file can have two kinds of password: a Document Open password and a Permissions password. If you are restricting printing and editing, you should add a Document Open password to enhance security.
• Opening the document with the correct Permissions password allows full access to the document. This unlimited access includes the ability to change the document’s passwords and access permissions.
• Opening the document with the correct Document Open password allows additional operations to be performed according to the set PDF security options.
With Enable PDF Security activated but Document Open and Permissions passwords not specified, the document will be encrypted, with user-level access, and a random Permissions password is generated; the user will not be prompted for a password, but nobody can have full access to the document.
With Enable PDF Security activated but only the Document Open password specified, a random Permissions password is generated, the document will be encrypted and the user will be prompted for a password. Again, nobody can have full access to the document. If both passwords are specified, the document will be encrypted and the user will be prompted for a password; depending on the password entered, the user can have full access, or only restricted access to the document.