Re: [webauthn] RPs cannot show "You've Already Registered This Authenticator" Message

@leshi Oh, my bad - I guess I was reading [an outdated draft?][ctap]

>1. If the excludeList parameter is present and contains a credential ID that is present on this authenticator, terminate this procedure and return error code CTAP2_ERR_CREDENTIAL_EXCLUDED.

@kpaulh Ah, a fake sign request is a clever way to work around it! That seems to me like a good solution: reply with some kind of `AlreadyRegisteredError` if the user does confirm the sign action, and the ambiguous `NotAllowedError` if the user does not confirm it.

I suppose that _could_ be confusing if the authenticator has a rich interface and makes create and sign operations substantially different. I imagine that could perhaps become an issue with U2F on "Intel Online Connect", for example, but it seems minor compared to the other issues discussed here.

[ctap]: https://fidoalliance.org/specs/fido-v2.0-rd-20170927/fido-client-to-authenticator-protocol-v2.0-rd-20170927.html#authenticatorMakeCredential

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Received on Friday, 16 February 2018 21:30:51 UTC