Canon PIXMA MP280 Series Advanced Manual page 399

Important
Up to 32 single-byte alphanumeric characters can be used for the password. Passwords are
case sensitive.
Select both checkboxes to set both Document Open Password and Permissions Password.
You cannot use the same password for both.
3.
Click OK.
The Confirm Document Open Password or Confirm Permissions Password dialog box opens.
Document Open Password
Permissions Password
4.
Re-enter the password and click OK.
The Save as PDF file dialog box returns.
Important
If you close the Save as PDF file dialog box without clicking Save, the settings in the Password
Security -Settings dialog box will be deleted.
Passwords are deleted once the file is edited. Reset the passwords when saving edited files.
Note
If you set the passwords via the PDF Settings dialog box, the PDF Settings dialog box returns.
Click OK. The Save as PDF file dialog box returns.
5.
Click Save.
Files are saved according to the settings.