Dale, Hi! And, thanks for your review comments in-line. spt > On Feb 18, 2020, at 22:07, Dale Worley via Datatracker <noreply@xxxxxxxx> wrote: > > Reviewer: Dale Worley > Review result: Ready with Issues > > I am the assigned Gen-ART reviewer for this draft. The General Area > Review Team (Gen-ART) reviews all IETF documents being processed by > the IESG for the IETF Chair. Please treat these comments just like > any other last call comments. > > For more information, please see the FAQ at > > <https://trac.ietf.org/trac/gen/wiki/GenArtfaq>. > > Document: draft-ietf-lamps-5480-ku-clarifications-00 > Reviewer: Dale R. Worley > Review Date: 2020-02-18 > IETF LC End Date: 2020-02-07 > IESG Telechat date: [unknown] > > Summary: > > This draft is on the right track but has open issues, described > in the review. > > The text is difficult to follow in places. I believe that the WG has > a clear understanding of what is intended, but a few small editorial > errors have unfortunately rendered the text incorrect and > contradictory to RFC 5480. Sometimes when you are too familiar with the context you assume too much so a fresh set of eye can help! > Note that I am unfamiliar with the details of PKI certificates; this > review is based largely on what I have learned from RFC 5480 and this > I-D. > >> From the discussion it appears that id-ecDH and id-ecMQV are "key > agreement algorithms" and that, as such, they should not be used with > keyEncipherment or dataEncipherment. [this draft, section 3] > Conversely, id-ecPublicKey is not a "key agreement algorithm". [RFC > 5480, section 2.1.2, para. 1, sentence 1] Ah ... this might be where some of misunderstanding comes from because id-ecPublicKey MAY be a key agreement algorithm that is why it is “unrestricted”. In other words, when key agreement certificates can include the following OIDs: id-ecDH (for an EC DH algorithm), id-ecMQV (for EC MQV), or id-ecPublicKey (for any algorithm). Here’s the text from 5480 about id-ecPublicKey being used as key agreement algrithm: If the keyUsage extension is present in an End Entity (EE) certificate that indicates id-ecPublicKey in SubjectPublicKeyInfo, then any combination of the following values MAY be present: digitalSignature; nonRepudiation; and keyAgreement. > 1. Introduction > > This document corrects this omission, by updating Section 3 of > [RFC5480] to make it clear that neither keyEncipherment nor the > dataEncipherment key usage bits are set for key agreement algorithms. > > This could be clearer by replacing or augmenting "key agreement > algorithms" with a description of which of these algorithms are key > agreement algorithms, viz., id-ecDH and id-ecMQV. Otherwise, one must > first have read RFC 5480 to understand this introduction correctly. See above. I also pondered how much to put in the intro to accommodate those readers that are not as familiar with RFC 5480. I went the minimal route since this is supposed to be just adding two sentences to RFC 5480. I sure hope people that are not intimately familiar with RFC 5480 do immediately go read RFC 5480 because this draft isn’t all that much use without doing so :) > 3. Updates to Section 3 > > If the keyUsage extension is present in a certificate that indicates > id-ecPublicKey as algorithm of AlgorithmIdentifier [RFC2986] in > SubjectPublicKeyInfo, then following values MUST NOT be present: > > keyEncipherment; and > dataEncipherment. > > If the keyUsage extension is present in a certificate that indicates > id-ecDH or id-ecMQV in SubjectPublicKeyInfo, then the following > values also MUST NOT be present: > > keyEncipherment; and > dataEncipherment. > > The structure of this section is peculiar, since it presents almost > the same text about "id-ecPublicKey" and about "id-ecDH or id-ecMQV". > If the intention is to say the same thing about all three, these > should be folded together. There are two reasons I’d like to not merge these two bits of text: 1. Agreed it is a bit odd, but it does mirror RFC 5480, which talks about id-ecPublicKey for CA certificates and then EE certificates and then id-ecDH/id-ecMQV. I guess we could collapse it, but for me then it’s a style thing and I’d rather mimic the RFC it’s updating. 2. With separate sentences we leave open the door for ECC encryption algorithms like ECIES <https://itectec.com/spec/c-3-elliptic-curve-integrated-encryption-scheme-ecies/> These algorithm need a lot of metadata (including EC point, KDF algorithm, hash algorithms, metadata of hash or KDF, etc…), and we are not sure, but believe, when specified they will not use id-ecPublicKey. However, they may use SubjectPublicKeyInfo for their metadata. If we integrate two sentence together, a possible future ECIES draft will conflict with our draft. > It is also not clear why the first paragraph refers to > AlgorithmIdentifier but the second paragraph uses SubjectPublicKeyInfo > to refer to essentially the same thing. I am pretty sure we did that to provide some context for where the OIDs go, but you are right the first paragraph could just of easily been: If the keyUsage extension is present in a certificate that indicates id-ecPublicKey in SubjectPublicKeyInfo, I will make that change. > But this text appears to contradict the statement in [RFC 5480] that > the usage of id-ecPublicKey is "unrestricted" and is not a key > agreement algorithm, in which case the first paragraph should say "the > following values MAY be present". (In which case, the "also" in the > 2nd paragraph should be omitted.) See above. Cheers, spt -- last-call mailing list last-call@xxxxxxxx https://www.ietf.org/mailman/listinfo/last-call
