Re: [webauthn] Why not email/username as user.id / user handle? (#1763)

The text in question was added in PR #1041 which was motivated by issue #578. It's more to do with not revealing the identity of an authenticator's owner without authentication, for example if a security key is stolen or dropped on the street. Authenticators are required to keep `name` and `displayName` secret unless they've authenticated the user, but may reveal the user handle without authentication.

As a concrete example, [CTAP 2.0](https://fidoalliance.org/specs/fido-v2.0-ps-20190130/fido-client-to-authenticator-protocol-v2.0-ps-20190130.html#authenticatorGetAssertion) reveals user handles without authentication when called with empty `allowCredentials`. This is also the default in CTAP 2.1, but many client platforms now set the [`credProtect` extension](https://fidoalliance.org/specs/fido-v2.1-ps-20210615/fido-client-to-authenticator-protocol-v2.1-ps-20210615.html#sctn-credProtect-extension) to keep credential existence secret unless the user passes user verification or the caller already knows the credential ID.

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Received on Wednesday, 6 July 2022 13:04:30 UTC