How to password protect PDF documents or files?
• Open the PDF file in Acrobat • Select File > Document Security from the menu • Got to the “Security Options” drop-down and select “Acrobat Standard Security” • Find the box labeled “Password required to open document” and place a check mark against it. • Edit or type the password • You can also add a password requirement for changing permissions or password.To add a a required password check the box against “required password to change permissions or password” and enter the password. However note that this password must be different from the one that you entered for securing or password protecting the PDF file. • If you want your PDF document to be password accessible to users with previous versions of Acrobat Reader (versions earlier than 5.0), do not change the 40-bit encryption setting. However if your users or audience will be using version 5 or later versions of the Reader (or the full Acrobat program) then you may use 128-bit encryption.
