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 valid combinations.

Type Value	0	1	2	4	5
Acrobat Version Required	Any	2.0	5.0	7.0	9.0
Encryption Key Length (bits)	None	40	128	128	256
Encryption Algorithm	Identity	RC4	RC4	Identity/RC4/AES	Identity/AES
Can Assemble
Can Change
Can Copy
Can Edit
Can Extract
Can Fill Forms
Can Print
Can Print Hi

See the Doc.Encryption property.