This property determines the level of encryption used when
saving the document. The default value of zero indicates that no
encryption will be used.
Higher levels of encryption provide higher levels of security
and more flexibility in applying permissions but also require more
recent versions of Adobe Acrobat to view. The table below details
The PDF 2.0 standard deprecates a number of these options as
being potentially insecure. The recommended set for PDF 2.0
compliant documents is Type 5 with SetCryptMethods AESV3.