"Drivers can be signed in one of two ways: catalog signing (which includes the signature in a catalog file) or embedded signing (which embeds the signature in the driver file)."
I was looking over a Microsoft document (http://msdn.microsoft.com/en-us/windows/hardware/gg463386) which explains that a embeded-signed driver is better than a catalog-signed driver for the Windows boot performance. I know that i must use signtool.exe to do that, the question is: how can i assign a cattagog-signed driver as embedded-signed? Is it possible? I need to get/buy new driver certificates?