We wanted to extract the Certificate from your PDF document and use a valid PKCS7 object in order to extract SignatureCustomAppearance. Nevertheless, we noticed that no certificate was found in your PDF using the code snippet.
We were able to extract signature however and its other properties can be seen as well e.g. Location, Date, Reason.
using (Document pdfDocument = new Document(dataDir + "DSC Signed.pdf"))
foreach (Field field in pdfDocument.Form)
SignatureField sf = field as SignatureField;
if (sf != null)
Signature s = sf.Signature;
var date = s.Date;
var location = s.Location;
var reason = s.Reason;
SignatureCustomAppearance signatureapp = s.CustomAppearance; // this is null because no customer appearance was used while signing the PDF
Stream cerStream = sf.ExtractCertificate(); // this is null
PKCS7 pKCS7 = new PKCS7(cerStream, ""); // this is null
Would you kindly provide details of the certificate using which this PDF was signed. We will further investigate the scenario why API is unable to extract it and share our feedback with you.