PeachPDF
PeachPDF.PdfGenerateConfig
PdfGenerateConfig.Encryption Property
Password protection and permissions for the generated PDF (AES-256, standard security handler revision 6).
null (the default) leaves the document unencrypted. See PdfEncryptionOptions.
A whole-document property: every AddPdfPages/AddPages call on one document must ask for the same
protection. Cannot be combined with PdfAConformance or PdfXConformance, both of which
forbid encryption - generation throws if it is.
public PeachPDF.PdfEncryptionOptions? Encryption { get; set; }