An ability to be able to tell using c# if 1) the number of times a PDF has been digitally signed and 2) if the signature(s) are valid.
Official response
Mario - GemBox
Hi, This feature request has been implemented and is available in the latest versions of GemBox.Pdf: https://www.gemboxsoftware.com/pdf/examples/c-sharp-vb-net-pdf-digital-signature-validation/1105 Regards, Mario