Re: [webauthn] Proposal/discussion: non-extractable CryptoKey output from the prf extension (#1895)

I think what @agl is saying is that because the PRF extension adds a prefix to the input salt, a future update of the PRF extension could add a new feature that uses a different prefix and returns a `CryptoKey` instead of a raw `ByteBuffer`. This would prevent the downgrade attack @MasterKale describes: if a script injection disables the `CryptoKey` setting, then the resulting `ByteBuffer` would contain a different result than the intended `CryptoKey` result, because the two are domain-separated by using different prefixes. (But @MasterKale is right that such a downgrade attack would work if there is no such domain separation.)

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Received on Wednesday, 7 June 2023 10:34:56 UTC