Digital signature not visible on page after signing PDF

When you use the SignFile function to add a digital signature to a PDF it adds an invisible digital signature which is not shown on any of the pages in the document. Instead the digital signature can be viewed by opening the PDF in Adobe Reader, Adobe Acrobat or another PDF editing application, and clicking […]

Advanced options for signing PDF files

The SignFile function in Debenu Quick PDF Library lets you sign PDF files using the PKCS#12 format (containing a certificate and private key). But sometimes more advanced signing options are required. This is why we’ve added two new functions: SetSignProcessPassthrough and GetSignProcessByteRange. These functions let you sign PDF files using signatures that were created externally. These advanced […]

Adobe Reader or Acrobat displays a “At least one signature has problems” message when signed PDF is opened

After signing a PDF file and then opening it in Adobe Reader or Adobe Acrobat the following message may be shown just below the toolbar:   This message does not indicate that the digital signature is invalid or corrupt. Instead it’s a poorly worded message from Adobe that causes unnecessary alarm. If you click on […]

Add visual digital signature to a PDF programmatically

Debenu Quick PDF Library lets you add visual digital signatures to PDF files programmatically with a few simple lines of code. It lets you sign existing signature form fields or will automatically create a signature form field with the name that you specify as part of the signing process. Here is some C# and Delphi […]