Re: [jose] 🔔 WGLC of draft-ietf-cose-webauthn-algorithms

Neil Madden <> Fri, 20 September 2019 09:35 UTC

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From: Neil Madden <>
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Date: Fri, 20 Sep 2019 10:35:29 +0100
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To: ivaylo petrov <>
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Subject: Re: [jose] =?utf-8?q?=F0=9F=94=94_WGLC_of_draft-ietf-cose-webauthn-a?= =?utf-8?q?lgorithms?=
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Thanks, I wasn't aware of this draft. It looks ok, just a few comments from me:

secp256k1 is mentioned in the context of signatures and the new ES256K JWS algorithm, but when it is registered in the JOSE Elliptic Curve registry it will also be usable for ECDH-ES encryption. The current draft mentions JOSE but only links to RFC 7515 (JWS). Is the intention that the curve be only used for signatures, or is it also intended for encryption?

I'm glad RS1 is not being registered for JOSE, although I'm still a bit surprised that it is being registered (even as deprecated) for a standard as new as COSE. I can't find any justification in the linked WebAuthn or CTAP specs for why this algorithm needs to exist at all. Section 5.3 says that it needs to be registered because some WebAuthn TPM attestations use it, but the very same section says that the algorithm MUST NOT be used by COSE implementations (is a WebAuthn implementation not a COSE implementation?). If the normative language in the spec is obeyed then the algorithm will never be used and so the registered identifier isn't needed.

-- Neil

> On 19 Sep 2019, at 16:40, ivaylo petrov <> wrote:
> Dear JOSE WG,
> As was suggested (thank you Jim), I am forwarding you this message about the COSE WGLC on draft-ietf-cose-webauthn-algorithms [1] as it has actions on "JSON Web Signature and Encryption Algorithms" and "JSON Web Key Elliptic Curve" registries.
> The working group last call will end on October 1, 2019.
> Please review and send any comments or feedback to the COSE working group. Even if your feedback is "this is ready", please let us know.
> Thank you,
> - Matthew and Ivaylo
> COSE Chairs
> [1]: <>
> On Tue, Sep 17, 2019 at 4:31 PM ivaylo petrov < <>> wrote:
> Dear all,
> This message starts the Working Group Last Call on the draft-ietf-cose-webauthn-algorithms [1].
> The working group last call will run for **two weeks**, ending on
> October 1, 2019.
> Please review and send any comments or feedback to the working group. Even if your feedback is "this is ready", please let us know.
> Thank you,
> - Matthew and Ivaylo
> COSE Chairs
> [1]: <>
> _______________________________________________
> jose mailing list