ChrisHalos wrote:
We implemented the transport hints starting in NEO firmware 3.4.6 (after the FIDO U2F v1.1 specification was released - before this, any device wouldn't implement this feature).
There are pros and cons to using transport hints on the service-side:
Pro:
* If the device was released after v1.1 of the spec was published (and the device vendor decided to implement this), the service can tell which transport protocols your device supports (USB, NFC, BLE). In this scenario, the service (Facebook in this case) knows the devices capabilities, and when attempting to log in from an Android device, the service knows if your device will work in that scenario. If the device doesn't support NFC, then Facebook won't ask for your U2F device - it'll ask for your backup method. It actually works great, for example, if you have a FIDO U2F Security Key or a YubiKey 4 (which don't support NFC) - it knows the device can't be used in that scenario and it falls back to the backup method.
Con:
* Transport hints, while it was added in v1.1 of the specification, it is not REQUIRED by the device manufacture. It is optional. So even now, a U2F device manufacturer doesn't have to include transport hints. Since Facebook uses transport hints to determine whether your device is capable of communicating over NFC, any device that doesn't implement this optional feature of the specification cannot be used over NFC.
*Any device manufactured before v1.1 of the specification was released obviously won't use transport hints, so it can't be used to log into a Facebook account over NFC.
In my opinion, the best way for the service to handle this is to:
(1) use transport hints to determine which communication protocol is supported by the device
(2) give users an option in their Security Key settings of their account to override this option, i.e. confirm that their device(s) supports NFC or BLE.
I understand. The topic is that I spent 60 Dollars in a security key and I can't use it to login facebook over NFC. Talk with Facebook is impossible, only users forums is available, and upgrade Yubikey firm is impossible. Incredible.