Re: [webauthn] Require non-null userHandle when allowCredentials is empty? (#1892)

@arianvp also notes in https://github.com/w3c/webauthn/issues/1909#issuecomment-1610131343 :

> The spec also says:
> 
> > [Discoverable credentials](https://w3c.github.io/webauthn/#discoverable-credential) store this identifier and return it as [response](https://w3c.github.io/webauthn/#dom-publickeycredential-response).[userHandle](https://w3c.github.io/webauthn/#dom-authenticatorassertionresponse-userhandle) in [authentication ceremonies](https://w3c.github.io/webauthn/#authentication-ceremony) started with an [empty](https://infra.spec.whatwg.org/#list-empty) [allowCredentials](https://w3c.github.io/webauthn/#dom-publickeycredentialrequestoptions-allowcredentials) argument.
> 
> Which kind of implies that a Discoverable credential should return `userHandle`
> 
> It makes sense that it is non-required in the `authenticatorAssertionResponse` as non-discoverable credentials can not return a `userHandle`
> 
> We can make the spec more clear maybe. But I think "Discoverable Credentials return `userHandle` when `allowedCredentials` is empty" is something that the spec currently (kind of in a round-about way) mandates

So it looks like there's a slight mismatch between the [User Handle definition](https://w3c.github.io/webauthn/#user-handle) (which says it's required) and the formal authenticatorGetAssertion algorithm (which doesn't explicitly say it's required).

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Received on Wednesday, 28 June 2023 07:42:43 UTC