Great Stuff! I am using your code for the C# version of the following:
http://www.spacegear.org/software/SGOJavaLibrary/index.html

Here is the problem:

CertificateStore

I noticed this comment in the code when I was trying to track down how to know when the password was invalid:

throw new CertificateException("The specified password is invalid."); // Do We need to notify user of this error?

YES!!!! It would be very nice to let the user know if a downloaded certificate is corrupted or they just misstyped the password.

Thanks,

In the following version of the library, the CreateFromPfxFile method will throw an ArgumentException if the specified password is invalid.