Re: [webauthn] Add excludeUsers to prevent creation of new keys for known users (#2309)

@Firstyear I think I explained this above already? Or maybe I am missing something. First, user IDs are "opaque [byte sequence](https://infra.spec.whatwg.org/#byte-sequence) with a maximum size of 64 bytes, and is not meant to be displayed to the user," so not sure how would such a list of random looking IDs be incriminating to anyone? Even more, RPs concerned about privacy of their users could always use a mapped IDs used only for Webauthn user IDs which are then mapped to real user IDs used elsewhere in the system. But more importantly, RPs should not put into `excludeUsers` a list of all IDs known to the RP, only IDs they have some additional information that they belong to the user currently signing-in. Exactly the same as with `excludeCredentials` where RP does not list credentials of everyone known to the RP.

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Received on Friday, 11 July 2025 05:56:56 UTC