Re: [webauthn] Clarify the need for truly randomly generated challenges (#1856)

I'm trying to understand the various attack vectors around challenge generation. The assertion case makes a lot of sense to me, but I'm having trouble understanding why the challenge matters in the attestation case. Specifically, why is [step #8 important](https://www.w3.org/TR/webauthn/#sctn-registering-a-new-credential)?

1. (challenge generated in trusted environment) -> I asked "you" to show proof of real-time ownership
2. (challenge generated in untrusted environment) -> Someone asked "you", or someone else, to prove previous ownership

Is this the right way to think about that? Since this uses a trust-of-first-use model... what's the worst case scenario if the challenge isn't generated in a trusted environment?

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Received on Friday, 9 June 2023 16:55:18 UTC