OpenSK VS libfido2

https://github.com/google/OpenSK works, it runs on something like this $15 board. Could do with a case though.

https://www.nordicsemi.com/About-us/BuyOnline?search_token=n...

There are a huge number of other vendors supporting Webauthn apart from Yubikey. (From the top of my head Nitrokey, Solo, Tomu, Mooltipass, Ledger, Trezor, Google Titan, OnlyKey, Token2).

You could also use the system TPM (https://github.com/psanford/tpm-fido).

A brief search didn't yield any FIDO2 software-only solutions for Linux, but I see no reason why in principle you couldn't implement it (perhaps interfacing https://github.com/google/OpenSK through hidg - similar projects do exist for U2F).

Cloudflare does, using a security key not found in the FIDO Metadata Service will unfortunately not work. This precludes the use of any hacker-friendly solution (making your own).

> Supported: All security keys found in the FIDO Metadata Service 3.0, unless they have been revoked for security reasons.

https://support.cloudflare.com/hc/en-us/articles/44068890480...

Attestation keys, as they're currently used, aren't very "privacy friendly" and it's much worse for those who wish to create their own key.

> Usually, the attestation private key is shared between a batch of at least 100,000 security keys of the same model. If you build your own OpenSK, your private key is unique to you. This makes you identifiable across registrations: Two websites could collaborate to track if registrations were attested with the same key material. If you use OpenSK beyond experimentation, please consider carefully if you want to take this privacy risk.

https://github.com/google/OpenSK/blob/f2496a8e6d71a4e8388849...

There are a number of FOSS solutions.

- https://github.com/google/OpenSK <- DIY solution

- https://solokeys.com/

- https://www.nitrokey.com/

The issue with any FOSS solution is that FIDO requires an attestation private key which is shared between a batch of at least 100,000 security keys. Using a DIY or cli app (application running on the host) solution will likely mean you'll be generating that private key yourself, this makes you identifiable across registrations.

I'm not sure what you're replying to--this scheme is much closer to self-signed X509 client certs, not FIDO. But regarding FIDO, it does not prevent user-controlled hardware; it's up to RPs to choose if they require specific device manufacturers or not.

In my experience, the vast majority of (consumer) RPs do not require specific batch attestation, which is why you can make your own FIDO key: https://github.com/google/OpenSK.

I am under the impression support for attestation was controversial in FIDO--it's clearly useful for enterprise scenarios (e.g. where an enterprise requires some silly certification like FIPS: https://support.yubico.com/hc/en-us/articles/360016614760-Ac...), but there's always the risk that consumer-facing RPs require it for no good reason.

My employer requires FIPS certification due to FedRAMP; I'd be interested in how you would propose to change FIDO such that--as now--I can use a single key for work and for all my consumer needs while eliminating attestation.

udev? yeah you should check that. https://github.com/Yubico/libfido2/blob/main/udev/70-u2f.rules Reload the udev rules after you change them if you do change them, and unplug the device, wait 15 seconds, plug it in again.

It's not extremely difficult at all to implement these! Heck, even at Google we use LibFido2 which is a free-to-use library (you can find it here if you want: https://github.com/Yubico/libfido2). Of course Google's version is a bit different and the creator of LibFido2 now works here, but all of these 2FA methods aren't particularly difficult to implement in the sense that most of the work (libraries, standards, exact specifications) is already done.

It could be possible yes. Libraries like https://github.com/Yubico/libfido2 already abstract away external keys (via CTAP) and the Windows WebAuthn API, which allows you to use Windows Hello for signing in using eg a Logitech Brio webcam.

https://fidoalliance.org https://loginwithfido.com https://w3.org/TR/webauthn-2/ https://fidoalliance.org/specs/fido-v2.1-ps-20210615/fido-client-to-authenticator-protocol-v2.1-ps-20210615.html https://github.com/yubico/Python-Fido2 https://github.com/yubico/libfido2

They suggest using this libfido2 library to connect with the hardware devices. I don't really know much about OSS licenses and which are the most "free" so you'll have to decide that for yourself.