Retrieving signature from CERT or PDF file of signee.

I was successful in obtaining the name of the signature by putting JavaScript into the form. Now the document was checked out in SharePoint. When it is checked back in I want to place in the signed property the field. Has anyone used JavaScript to communicate with SharePoint?

thanks,

Mark

First a correction. In my previous posts I called the CMS key in PDF /V. That was an error. The key is /Contents.

After thinking more about your problem I found two more solutions that may be easier for you.

1. You can use Acrobat JavaScript. You write a JavaScript that loops through all signature fields in a PDF file, gets SignatureInfo object for each signature and the name of the signer property in the SignatureInfo object. Then you can write the PDF filename and signer names to a file.

This is the general approach, To automate it you'll place your JavaScript in Acrobat's JavaScripts folder (see Instructions for Installing Folder Level Scripts (Automation Tools) and Plug-ins and https://acrobatusers.com/tutorials/so-where-does-javascript-go-in-acrobat )  and then you can create an Action which will open and close all your PDFs. When each PDF is opened, your JavaScript will be executed.

2. If you can extract the /Contents Hex string from a PDF and transform it to a binary you can then write a program using packages like Bouncy Castle (bouncycastle.org ) to write a Java or C# program that would get you a signature's signer. The input to your program will be the Hex /Contents string which your program will convert to binary and then pass it as input to Bouncy Castle method that returns the signer.

Neither of the two methods are easy but it is doable.

Good luck.

It is very difficult to understand what you're asking. What is the "signature file" you start with? Is it a signed PDF? Have you wrote a program in C# to export, presumably, PDF to XML or did you get the program from someone else?

Apparently this program did not process the PDF file properly. A digital signature in a PDF is a special type of a form field (see PDF specification). If a program correctly traverses the PDF object tree and writes out all objects it finds, it will write out the content of signature fields.

From the PDF point of view a Digital Signature in PDF just a Hex string that represents Hex-encoded PKCS#7 object. The program that parses PDF needs to also properly parse the PKSC#7 objects in the signature form fields if you want to extract the certificate with which the signature was signed and the signer's name in it.