See gnuk-users@gnupg.org, "Logging to Windows with Gnuk", from Alexandr Zarubkin azarubkin@gmail.com:
I've managed to log into Windows using a certificate stored on Gnuk. I had to add MSE command support and raise the reported OpenPGP version to 3.3. It's just a proof of concept, but it works. The changes are located at https://github.com/me21/gnuk and https://salsa.debian.org/me21/gnuk, platformio branch.
The tests were performed on the virtual machine running Windows 7.
See gnuk-users@gnupg.org, "Logging to Windows with Gnuk", from Alexandr Zarubkin azarubkin@gmail.com: