How to verify an exe/dll/sys is original from Microsoft?

Question

I need some easy API to verify that a PE file is valid & Microsoft signed just like SignTool. Where should I start? Could this be done with CAPICOM?

Answer 1

Example C Program: Verifying the Signature of a PE File:
http://msdn.microsoft.com/en-us/library/aa382384(VS.85).aspx