Re: [webauthn] residentKey: "preferred-if-unlimited"? (#1822)

> why would you need to store the cred ID in cookies?
> 
> you just enter a user name and the server gives back the credential IDs in response just as if using U2F but without needing a password but instead requiring UV.

See the [Username Enumeration](https://www.w3.org/TR/2021/REC-webauthn-2-20210408/#sctn-username-enumeration) and [Privacy leak via credential IDs](https://www.w3.org/TR/2021/REC-webauthn-2-20210408/#sctn-credential-id-privacy-leak) privacy considerations.

But yes, these are noteworthy considerations, not all-encompassing bans (and honestly we have no data on how hard it would actually be to de-anonymize someone just by analyzing `allowCredentials` lists between accounts or RPs). And they are obviously much less relevant if your user profiles are public, for example.

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Received on Thursday, 10 November 2022 13:41:56 UTC