Use the CreateSecurityHandler method to initialize this property or create and assign the handler directly.

For example, the following code may be used to password protect the PDF: wordLayout.SaveAsPdf("output.pdf", null, new PdfOutputSettings { SecurityHandler = new StandardSecurityHandlerRev6 { UserPassword = "231", OwnerPassword = "#%f8JK", PrintingPermissions = PrintingPermissions.Disabled, EditingPermissions = EditingPermissions.Disabled, CopyContent = false } });