Javascript and Digital Signatues

Hello,
I am writing an automated script that will monitor a directory for pdf files. When digitally signed documents are dropped into this directory I need the script to open the file, extract its signature, mainly the certificate issuer, (in this case we are using our own certificate authority) and verify that we are in fact the issuer of that certificate.
 
So I guess the question is, how to extract the certificate issuer, and two how to do this in an automated way, instead of manually running the script through the debugger.