Signaling Cryptographic Algorithm Understanding in DNS Security Extensions (DNSSEC)
draft-ietf-dnsext-dnssec-algo-signal-10

[Ballot comment]
After discussion, it sounds like we're in agreement that some clarification on why a client MUST NOT send DAU/DHU/N3U if it's not setting DO would be a good thing, and some review of the other requirements language (in particular I suggest removing the "MUST send DO if you send DAU/DHU/N3U") is in order. I will work with the AD and authors to get this in before final approval.

Section 5, paragraph 2: s/DNSSEC-OK (OK)/DNSSEC-OK (DO)

[Ballot comment]
Why is there a need for separate DHU and N3U options?  It seems like if an implementation has a hash, then it has the has.  Are there real implementations for which these differ?

The combination algorithm for recursive resolvers seems backwards; it results in a list of algorithms such that at least one of the stub and recursive resolvers can validate.  It seems like you would want to know how many clients there are out there for which you MUST use a given algorithm.  Since either the stub or recursive resolver can fail the resolution on validation failure, you would thus want the intersection of the two lists, not the union.

[Ballot discuss]
1. The combination algorithm for recursive resolvers seems backwards; it results in a list of algorithms such that at least one of the stub and recursive resolvers can validate.  It seems like you would want to know how many clients there are out there for which you MUST use a given algorithm.  Since either the stub or recursive resolver can fail the resolution on validation failure, you would thus want the intersection of the two lists, not the union.

[Ballot comment]
Why is there a need for separate DHU and N3U options?  It seems like if an implementation has a hash, then it has the has.  Are there real implementations for which these differ?

[Ballot discuss]
Overall issue: I do not understand the requirement that a client MUST NOT send DAU, DHU and/or N3U if DO is not set and MUST set DO if DAU, DHU and/or N3U are sent. I do not see any harm in saying that I normally support such-and-so DNSSEC algorithms even if on a particular query I don't want the DNSSEC RRs back. Indeed, 3.1.1 says that sometimes validating resolvers don't set the DO bit. It might still be useful for the DAU, DHU and/or N3U to be sent. Unless there's an important reason to keep this requirement, which appears throughout sections 3 and 5 (and is included in the RFC Editor note for section 5), I suggest you just drop it.

If there *is* a reason to keep the requirement, please explain in the document. MUSTs and MUST NOTs that don't explain what harm they are trying to prevent are double-plus bad.

[Ballot comment]

- abstract: the draft does stuff, it doesn't "set out to" do
stuff, at least not anymore

- section 4: not sure if the write-up is a bit out of date,
but personally I prefer the text in -10 of the draft to using
"[RFC525-422]" as given in the write-up

- section 7 or earlier: it'd be nice to point at the IANA
registries if those had stable URLs. I can never remember if
they do or not;-)

- section 8: I think you maybe ought add another security
consideration something like: 'If a client continues to
support a "broken" algorithm that would allow an attacker to
prepare bogus but cryptographically valid DNS responses then
advertising that fact via this extension could make it easier
for the attacker to exploit such a vulnerability. The
solution for such clients is to remove support for such
"broken" algorithms as soon as possible.'

- The secdir review [1] mentioned a possible DoS. I don't see
the threat myself, but it'd be good if the authors responded
to that, just in case. (Sorry if you've done that already and
I missed it.)

  [1] http://www.ietf.org/mail-archive/web/secdir/current/msg03919.html

IESG/Authors/WG Chairs:

IANA has reviewed draft-ietf-dnsext-dnssec-algo-signal-09.  Authors should review the comments and/or questions below.  Please report any inaccuracies and respond to any questions as soon as possible.

We have a question about the action requested in the IANA Considerations section of this document.

We understand that, upon approval of this document, there is a single action which we must complete.

In the DNS EDNS0 Options subregistry of the Domain Name System (DNS) Parameters registry located at:

http://www.iana.org/assignments/dns-parameters/dns-parameters.xml#dns-parameters-11

three new options are to be registered as follows:

Value: [ TBD-at-registration ]
Name: DAU
Status: Standard
Reference: [ RFC-to-be ]

Value: [ TBD-at-registration ]
Name: DHU
Status: Standard
Reference: [ RFC-to-be ]

Value: [ TBD-at-registration ]
Name: N3U
Status: Standard
Reference: [ RFC-to-be ]

IANA Question -> IANA notes that the EDNS0 options subregistry is managed through Expert Review as defined in RFC5226. Has a designated expert for
the EDNS0 Options subregistry been designated?

We understand that this is the only action required to be completed upon approval of this document.

Note:  The actions requested in this document will not be completed until the document has been approved for publication as an RFC. This message is only to confirm what actions will be performed.

The following Last Call announcement was sent out:

From: The IESG
To: IETF-Announce
CC:
Reply-To: ietf@ietf.org
Subject: Last Call:  (Signaling Cryptographic Algorithm Understanding in DNSSEC) to Proposed Standard


The IESG has received a request from the DNS Extensions WG (dnsext) to
consider the following document:
- 'Signaling Cryptographic Algorithm Understanding in DNSSEC'
  as Proposed Standard

The IESG plans to make a decision in the next few weeks, and solicits
final comments on this action. Please send substantive comments to the
ietf@ietf.org mailing lists by 2013-04-03. Exceptionally, comments may be
sent to iesg@ietf.org instead. In either case, please retain the
beginning of the Subject line to allow automated sorting.

Abstract


  The DNS Security Extensions (DNSSEC) were developed to provide origin
  authentication and integrity protection for DNS data by using digital
  signatures.  These digital signatures can be generated using
  different algorithms.  This draft sets out to specify a way for
  validating end-system resolvers to signal to a server which digital
  signature and hash algorithms they support.





The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-dnsext-dnssec-algo-signal/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-dnsext-dnssec-algo-signal/ballot/


No IPR declarations have been submitted directly on this I-D.

The document looks solid.  One proposal relating to the server considerations section:

OLD
If the options are present but the DNSSEC-OK (OK) bit is not set, the server does not do any DNSSEC processing, including any recording of the option(s).

NEW
If the options are present but the DNSSEC-OK (OK) bit is not set, the server MUST NOT do any DNSSEC processing, including any recording of the option(s).

I suggest this because the previous paragraph contains normative language for a similar situation, so it seems inconsistent not to use the same language here.  If the authors agree, this could be addressed by the RFC editor.

(1) What type of RFC is being requested (BCP, Proposed Standard, Internet Standard, Informational, Experimental, or Historic)?  Why is this the proper type of RFC?  Is this type of RFC indicated in the title page header?

The requested type is Proposed Standard.

The type of RFC requested in the title page header is Standards Track.

Standards Track is requested due to the in the document definition of EDNS0 usage to signal DNSSEC algorithm parameters, which in the longer term should be both in an easy way normatively referenced from any kind of IETF document and go through the Standards Track Process for validation of interoperability and implementability.

(2) The IESG approval announcement includes a Document Announcement Write-Up. Please provide such a Document Announcement Write-Up. Recent examples can be found in the "Action" announcements for approved documents. The approval announcement contains the following sections:

Technical Summary

The DNS Security Extensions (DNSSEC) were developed to provide origin authentication and integrity protection for DNS data by using digital signatures. These digital signatures can be generated using different algorithms. This draft sets out to specify a way for validating end-system resolvers to signal to a server which digital signature and hash algorithms they support.

Working Group Summary

The DNSEXT WG members reviewed and commented on previous revisions of the  document. All substantive comments were reviewed and the document updated accordingly. Most reviewers feel that the proposed extensions would be harmless to the protocol and would be useful for measureing cryptographic algorithm implementation uptake in clients. A minority of the reviewers questioned the need for such signalling. No reviewers flagged the existence of the proposed EDNS0 extension create interoperability or deployment problems.

Document Quality

The document does not change any protocol or change client or server processing in any significant way, but proposes a new option to EDNS(0) to aid authoritative DNS zone administrators to measure cryptograpic algorithm code in clients.

Personnel

Who is the Document Shepherd? Who is the Responsible Area Director?

Patrik F?ltstr?m is the Document Shepherd, and Ralph Droms is the Responsible Area Director.

(3) Briefly describe the review of this document that was performed by the Document Shepherd.  If this version of the document is not ready for publication, please explain why the document is being forwarded to the IESG.

The shepherd reviewed the document for content, to make sure that it was in keeping with the WG's consensus, and ensure that its references were correct. It has gone through a few revisions. The document is at this point ready for publication.

(4) Does the document Shepherd have any concerns about the depth or
breadth of the reviews that have been performed? 

In each round of reviews a few (~5) individuals have engaged in detailed review of the document. The questions and issues brought up have been responded to and the document accordingly updated. Each review cycle have not brought up exactly the same reviewers but in the last review cycle the same comments have come up. Comments that do not have any impact on deployment or interoperability.

(5) Do portions of the document need review from a particular or from broader perspective, e.g., security, operational complexity, AAA, DNS, DHCP, XML, or internationalization? If so, describe the review that took place.

No.

(6) Describe any specific concerns or issues that the Document Shepherd has with this document that the Responsible Area Director and/or the IESG should be aware of? For example, perhaps he or she is uncomfortable with certain parts of the document, or has concerns whether there really is a need for it. In any event, if the WG has discussed those issues and has indicated that it still wishes to advance the document, detail those concerns here.

The only questions in the last review cycle have been whether the mechanism described in this document is really needed, whether it will be deployed etc. The basis though for the creation of this document in the first place was already around IETF-75 in Stockholm 2009 made in the IETF that due to the (potential) diversity of algorithms in use there was a need for a standardized way of signalling what algorithms where acceptable.

There has not been any detailed discussion whether such a mechanism actually will be deployed or used, but there is as stated a consensus that *if* it is to be deployed, it must be standardized. This document describes that signalling.

(7) Has each author confirmed that any and all appropriate IPR disclosures required for full conformance with the provisions of BCP 78 and BCP 79 have already been filed. If not, explain why.

Yes.

(8) Has an IPR disclosure been filed that references this document? If so, summarize any WG discussion and conclusion regarding the IPR disclosures.

No.

(9) How solid is the WG consensus behind this document? Does it represent the strong concurrence of a few individuals, with others being silent, or does the WG as a whole understand and agree with it? 

There appear to be no objections to the proposed solution. Comments from reviewers have been addressed in the document. Reviewers have made statements saying they support the draft while providing comments for improvement.

(10) Has anyone threatened an appeal or otherwise indicated extreme discontent? If so, please summarise the areas of conflict in separate email messages to the Responsible Area Director. (It should be in a separate email because this questionnaire is publicly available.)

No.

(11) Identify any ID nits the Document Shepherd has found in this document. (See http://www.ietf.org/tools/idnits/ and the Internet-Drafts Checklist). Boilerplate checks are not enough; this check needs to be thorough.

Nits all pass. 

(12) Describe how the document meets any required formal review criteria, such as the MIB Doctor, media type, and URI type reviews.

N/A

(13) Have all references within this document been identified as either normative or informative?

Yes.

(14) Are there normative references to documents that are not ready for advancement or are otherwise in an unclear state? If such normative references exist, what is the plan for their completion?

Yes: draft-ietf-dnsext-rfc2671bis-edns0. The draft in question is completing WGLC and will be ready for Last Call shortly.

(15) Are there downward normative references references (see RFC 3967)? If so, list these downward references to support the Area Director in the Last Call procedure.

No.

(16) Will publication of this document change the status of any existing RFCs? Are those RFCs listed on the title page header, listed in the abstract, and discussed in the introduction? If the RFCs are not listed in the Abstract and Introduction, explain why, and point to the part of the document where the relationship of this document to the other RFCs is discussed. If this information is not in the document, explain why the WG considers it unnecessary.

This draft does not update any existing RFC's, but lists a new option parameter of an existing RFC (EDNS(0)).

(17) Describe the Document Shepherd's review of the IANA considerations section, especially with regard to its consistency with the body of the document. Confirm that all protocol extensions that the document makes are associated with the appropriate reservations in IANA registries. Confirm that any referenced IANA registries have been clearly identified. Confirm that newly created IANA registries include a detailed specification of the initial contents for the registry, that allocations procedures for future registrations are defined, and a reasonable name for the new registry has been suggested (see RFC 5226).

The document does not actually change or create any IANA registry, but it does use existing IANA registries used with DNSSEC. Changes to those registries will not effect this document.

(18) List any new IANA registries that require Expert Review for future allocations. Provide any public guidance that the IESG would find useful in selecting the IANA Experts for these new registries.

None.

(19) Describe reviews and automated checks performed by the Document Shepherd to validate sections of the document written in a formal language, such as XML code, BNF rules, MIB definitions, etc.

N/A.