This YubiKey implementation is not FIDO U2F - it is using a challenge and response technique with HMAC-SHA 256 – here is a bit more detail from Microsoft https:

This YubiKey implementation is not FIDO U2F - it is using a challenge and response technique with HMAC-SHA 256 – here is a bit more detail from Microsoft https://msdn.microsoft.com/en-us/windows/uwp/security/companion-device-unlock https://msdn.microsoft.com/en-us/windows/uwp/security/compan...