-03 has been published, which addresses Jim's review comments on -02 in the
manner described in the reply below. Thanks again for your reviews, Jim.
-- Mike
From: Mike Jones
Sent: Tuesday, October 29, 2019 4:20 PM
To: Jim Schaad <[email protected]>; [email protected]
Subject: RE: [COSE] Review draft-ietf-cose-webauthn-algorithms-02.txt
Replies are inline, prefixed by "Mike>".
-----Original Message-----
From: COSE <[email protected]<mailto:[email protected]>> On Behalf Of
Jim Schaad
Sent: Tuesday, October 29, 2019 12:39 PM
To: [email protected]<mailto:[email protected]>
Subject: [COSE] Review draft-ietf-cose-webauthn-algorithms-02.txt
1. The document needs to have a short title added to it.
Mike> I've added this "abbrev" value in the current editor's draft "COSE & JOSE
Registrations for WebAuthn Algs", which fits in the available space.
2. Abstract - The text "FIDO Alliance FIDO2 Client to Authenticator Protocol"
needs to get cleaned up. It is not clear to me if FIDO2 is supposed to be an
abbreviation of the previous FIDO Alliance or not. Flip the sentence to use
from or insert specification earlier.
Mike> I've deleted "FIDO2" (which was being used as an adjective applying the
spec name).
3. Section 1 - I am not sure why you are using the term "related" rather than
"the" in this section. This seems to be different than the abstract in that
feature. Relate makes me think that it is something that is different but
similar in this case.
Mike> I've deleted "related".
4. While I guess it is reasonable to have the description of why things are
not recommended in the security considerations, I myself would not really think
of them as such. However not having a pointer from section 2 to that
information seems harsh as we are saying the are not recommended without have a
pointer to the discussion.
Mike> I've added the pointers.
5. I have problems with the following text: "Implementation of this algorithm
is RECOMMENDED because of its widespread use in decentralized systems and those
that chose it over the NIST curves." Firstly, this is an incorrect use of the
RFC 2119 language, this is not a protocol statement.
Mike> I've lowercased "recommended".
Secondly, this is not what the recommended column in table 2 means and thus is
trying to overload that column with something that is not real. Third, the
fact that people chose this over the NIST curves is not necessarily a reason
for the IETF to recommended its implementation.
Mike> Recall that the JOSE algorithms come with Implementation Requirements
(see https://tools.ietf.org/html/rfc7518#section-7.1.1), whose values are one
of Required, Recommended, Optional, Deprecated, or Prohibited. It's in that
sense that the word "Recommended" is being used - more than Optional but less
than Required. The COSE registry value that seems to most closely correspond
with this is "Recommended: True". (As I see it, it's unfortunate that COSE
compressed these five values down to two, but I realize that that's water under
the bridge, unless we want to reconsider this choice in the BIS COSE registry
instructions.)
6. I still want to see in the text the reasoning behind not just using the
current ECDSA algorithm in COSE.
Mike> I provided the reasoning in my response to your previous review. Having
a curve-specific algorithm identifier lets implementations do what you asked
about - ensuring that the curve associated with a key cannot be changed and the
modified key still be used.
7. Add text on checking point is on the curve to section 5.4
Mike> I assume you're talking about adding text like that in
https://tools.ietf.org/html/draft-ietf-oauth-jwt-bcp-07#section-3.4. I'll
admit that I'm not enough of an expert on secp256k1 usage to know whether an
on-curve check is what is called for or a different validation procedure. A
definitive reference would be highly appreciated. In particular, I don't know
whether the Galois y² = x³ + 7 finite field form used with secp256k1 is
amenable to a check that the (x, y) pair are on the curve or whether a
different check is needed.
Thanks again for your detailed reviews, Jim. I'll plan to publish a new draft
incorporating these issue resolutions before Monday's submission cutoff..
-- Mike
-----Original Message-----
From: COSE <[email protected]<mailto:[email protected]>> On Behalf Of
[email protected]<mailto:[email protected]>
Sent: Thursday, October 24, 2019 2:35 PM
To: [email protected]<mailto:[email protected]>
Cc: [email protected]<mailto:[email protected]>
Subject: [COSE] I-D Action: draft-ietf-cose-webauthn-algorithms-02.txt
A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the CBOR Object Signing and Encryption WG of the
IETF.
Title : COSE and JOSE Registrations for WebAuthn
Algorithms
Author : Michael B. Jones
Filename : draft-ietf-cose-webauthn-algorithms-02.txt
Pages : 13
Date : 2019-10-24
Abstract:
The W3C Web Authentication (WebAuthn) specification and the FIDO
Alliance FIDO2 Client to Authenticator Protocol (CTAP) specification
use CBOR Object Signing and Encryption (COSE) algorithm identifiers.
This specification registers the following algorithms in the IANA
"COSE Algorithms" registry, which are used by WebAuthn and CTAP
implementations: RSASSA-PKCS1-v1_5 using SHA-256, SHA-384, SHA-512,
and SHA-1, and ECDSA using the secp256k1 curve and SHA-256. It
registers the secp256k1 elliptic curve in the IANA "COSE Elliptic
Curves" registry. Also, for use with JSON Object Signing and
Encryption (JOSE), it registers the algorithm ECDSA using the
secp256k1 curve and SHA-256 in the IANA "JSON Web Signature and
Encryption Algorithms" registry and the secp256k1 elliptic curve in
the IANA "JSON Web Key Elliptic Curve" registry.
The IETF datatracker status page for this draft is:
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