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

That is a good point... Unfortunately CTAP2 specifies that consent is collected _after_ the CTAP2_ERR_CREDENTIAL_EXCLUDED error would be returned, so the two cases are not distinguishable to the client.

...Unless the client can ask the user up front if they intend to create a credential (i.e., something like Chrome's and Firefox's "share location?" popup: "foo.com would like to register your identity, proceed?")? In that case I suppose the client could return the EXCLUDED error early without any unintended information leak. Updating the spec to accommodate that shouldn't be too hard.

I don't immediately see any other ways to solve this without sacrificing the protection against the information leak.

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Received on Friday, 16 February 2018 20:40:31 UTC