advanced encryption #91

in some files I need to encrypt pdf file with 2 properties:

1. opening the pdf file does not require a password at all
2. making any changes (and if possible printing) would require the owner_pwd

I tried reading the source code but it seemed that this logic wont work with such code:

output_file = PdfFileWriter()
output_file.encrypt(user_pwd="", owner_pwd="password")