Thank you for contacting support.
You may check the validity of PDF signatures with below code snippet in your environment. However, the signatures in this particular PDF file, shared by you, are not validated by the API. This is a file specific problem and is already logged in our issue management system with ID PDFNET-43228. So you may try to validate some other PDF files by using shared code snippet and then share your kind feedback with us.
Document PDF_Doc = new Document(dataDir + "DocumentToValidate.pdf");
com.aspose.pdf.facades.PdfFileSignature PFS1 = new
if (PFS1.getSignNames().size() > 0)
for (String Cert_00:PFS1.getSignNames())
System.out.println("Not Valid !!!");
We hope this will be helpful. Please feel free to contact us if you need any further assistance.