For a given digitally signed file I need to extract the 1024 bit(RSA) public sign key that is shown in the attachment. Can someone tell me how to do that through python. Is there a specific python module that can extract the digital signature details? If that is not possible is there a command line utility that will do the same? I've already tried signtool and sigcheck but could not do it.

I would try using the gnu-pg module, as that will likely be helpful:

From the website:
"gnupg.py is a Python API which wraps the GNU Privacy Guard.

The GNU Privacy Guard (gpg, or gpg.exe on Windows) is a command-line program which provides support for programmatic access via spawning a separate process to run it and then communicating with that process from your program.

This project implements a Python library which takes care of the internal details and allows its users to generate and manage keys, encrypt and decrypt data, and sign and verify messages."