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Algorithm rollover is also discussed on namedroppers. Wouter listed some
other options you have when algorithm rollover and 5011 are both in place:

* Go MISSING.
use the steps for removal without the REVOKE publish step.  The key goes
into 5011-MISSING state.  And is removed after a time (180 or 366 days
or so).  This may be an alternative for non ZSK-KSK split zones, since
they want things easy, and this is easy.

* Sign the entire zone with the removed KSK while it is REVOKED as well.
Some find this distasteful, but really, it is only a DNSKEY flag, just
like the SEP flag and carries meaning only to operators.  If you have a
ZSK/KSK split you do not have to do this.

! The latter option is, I believe, not true. If you do not introduce a
  temporary ZSK, you will break 5011-aware resolvers (since they will
  stop using the revoked key for validation and now theres only
  signatures of one algorithm validating). So even with a single type
  key scheme, you need to introduce a (temporary) split when doing
  algorithm rollover.

  Nevertheless, I think the first option is nice to include into
  4641bis.

Best regards,
Matthijs

On 08/05/2010 09:43 AM, Matthijs Mekking wrote:
> There seems something went wrong with the layout on the previous try...
> 
> Matthijs
> 
> -------- Original Message --------
> Subject: 4641bis (draft 3 and 4) review - largely 5011 related
> Date: Thu, 05 Aug 2010 09:42:14 +0200
> From: Matthijs Mekking <[email protected]>
> To: [email protected]
> 
> 
> Hi Olaf,
> 
> I noticed there is already a version 4 out, but it merely covers changes
> in language and style. So, here is a review of version 3 of the document.
> 
> The KSK RFC5011-based rollover method says that the removed key must be
> post-published as revoked at least holdback timer long. However, that
> parameter is just a management value for the validating resolver. It
> should be post-published as revoked the Maximum Zone TTL long. Proposed
> text:
> 
>    RFC5011 increases the duration of key rollovers, because the
>    key to be removed must first be revoked. Thus, before the DNSKEY1
>    removal phase, DNSKEY1 must be published for one more Maximum Zone
>    TTL with the REVOKE bit set. The revoked key must be self-signed, so
>    in this phase the DNSKEY RRset must also be signed with DNSKEY1.
> 
> This is also true for algorithm rollover. Proposed text:
> 
>    Trust anchor algorithm rollover is as simple as a regular RFC5011
>    based rollover. The old trust anchor must be revoked before it is
>    removed from the zone.
> 
>    However, at every RRset there must be at least one signature for
>    each algorithm used in the DNSKEY RRset. This means that a different
>    key with the same algorithm, other than the revoked key, must
>    sign the entire zone. This can be the ZSK. More operations is
>    needed if the single type signing scheme is used. Before rolling the
>    algorithm, a new key must be introduced with the same algorithm as
>    the key that is candidate for revocation. That key can than
>    temporarily act as ZSK during the algorithm rollover.
> 
> End proposed text.
> Rolling the algorithm of only the KSK or only the ZSK is in my point of
> view infeasible and useless.
> 
> And one more RFC 5011 note: In section 4.2.3 (Compromise of Keys
> Anchored in Resolvers), it might be relevant to mention that RFC5011 can
> also recover from compromised keys, as long as at least one valid
> trust-anchor key remains uncompromised.
> 
> Finally, some editorial nits in version 4:
> - You replaced the names of the DNSKEYs in the tables (for example,
> DNSKEY_1 becomse DNSKEY_Z_1), but not in the text.
> 
> - In the ZSK pre-publish rollover method, at the DNSKEY removal stage,
> the text says re-sign with DNSKEY1. Although not necessary, it should
> also be re-signed with DNSKEY11 (DNSKEY_Z_11), because it does so in the
> table.
> 
> - In the ZSK double signature rollover method, at the DNSKEY removal
> stage, the text says "The key set now only containing DNSKEY 11, is
> re-signed with DNSKEY 1." Again, also resign with DNSKEY_Z_11. Also, the
> key set also containst DNSKEY_Z_11.
> 
> 
> Below are some more inline comments.
> 
> Best regards,
> 
> Matthijs
> 
> On 07/20/2010 06:20 PM, Olaf Kolkman wrote:
>>>>> - Point 1:
>>>>> Is the set of arguments presented for major operational choices (e.g.
> single versus ksk-zsk split,
>>>>> and key effectivity period) complete and are the arguments fairly
> represented?
> 
> ...
> 
>>>>> Addressing all these arguments and considerations has created a
> fairly
> long document.
>>>>> In fact the choice has been to make the document comprehensive in
> presenting the considerations
>>>>> while not giving strong recommendations one way or another. This
> causes the document to be rather
>>>>> long and raises the question of the target audience.
> IMO, I think it is relevant to present the reader with the possible
> options, including all its drawbacks and advantages. Later on, the
> reader can always seek into the document to find the section they deployed.
> 
>>>>> Also see:
>>>>>
> http://www.nlnetlabs.nl/svn/rfc4641bis/trunk/open-issues/KSK-ZSK-Split
>>>>>
>>>>> - Point 2:
>>>>> Should this document try to give strong recommendations or should a
> separate document (set) be made that gives
>>>>> recommendations for certain operational environments (e.g. BCP for
> root, BCP for TLD, BCP for enterprise)?
>>>>> I am looking for specific guidance but as a straw man for consensus:
> This document should not give strong
>>>>> recommendations but provide comprehensive arguments (like it does
> now); development of recommendations is
>>>>> left for later, either in a follow up (RFC4641bis-bis) or as a set of
> separate documents)
> 
> Based on the previous comments: yes.
> 
>>>>> -Point 3:
>>>>> There have also been some questions about what audience the document
> is trying to address.
>>>>>
>>>>> The document is targeted to the 'the authoritative side of the DNS
> equation'. Is that indeed what the WG wants?
>>>>> If so is that clear enough from the document. (Please send concrete
> suggestions to improve if not).
> 
> Yes.
> 
>>>>> If there is consensus that the document talks to the authoritative
> side then the chairs may want to ask the
>>>>> question as to whether there a need for separate guidance for
> resolver
> operators, and maybe even ask for volunteers ;-)
>>>>>
>>>>>
>>>>> The following points are more detailed.
>>>>>
>>>>> -Point 4:
>>>>>
> http://www.nlnetlabs.nl/svn/rfc4641bis/trunk/open-issues/trust_anchor_configuration
>>>>>
>>>>> Version 3 of the document has tried to address these issues
> (pending a
> conclusion of point 3 above) but in order
>>>>> to close this issue I would like to know whether "the document
> [is] in
> any way restrictive on not using 5011,
>>>>> or is its consideration for advising RFC5011 to strong?" Silence on
> this point will be taken as finding the right balance.
> 
> The text now says:
>    It is therefore recommended to roll KSKs that are likely to be used
>    as trust-anchors if and only if those rollovers can be tracked using
>    standardized (e.g.  RFC5011) mechanisms.
> 
> To avoid confusion, I would add "on a regular basis" here.
> 
>>>>> -Point 5:
>>>>>
> http://www.nlnetlabs.nl/svn/rfc4641bis/trunk/open-issues/Signature_validity
>>>>> Text added in 4.4.2, is this text satisfactory
>>>>>
> http://tools.ietf.org/html/draft-ietf-dnsop-rfc4641bis-03#section-4.4.2
>>>>>
>>>>> The paragraph talks about a Maximum signature validity and Minimum
> validity period in fairly broad terms.
>>>>> It also provides motivations for differentiating Signature Validity
> periods for different RRsets in a zone,
>>>>> those motivations are few and week.
>>>>>
>>>>> Again, is this section complete in providing arguments and are the
> arguments fair? If not, what are concrete
>>>>> recommendations for improvement.
> I am fine with the text in this section/
> 
>>>>> - Point 6
>>>>>
>>>>> Is Appendix B useful? Or drop it?
> Already dropped in version 4, I see. Good.
> 
>>>>> - Point 7
>>>>> Any objections on closing the following:
>>>>> -
> http://www.nlnetlabs.nl/svn/rfc4641bis/trunk/open-issues/Key_algorithm_roll
> 
> Yes, since the issue with RFC5011 popped up during ietf78.
> 
>>>>> -
> http://www.nlnetlabs.nl/svn/rfc4641bis/trunk/open-issues/ZSK-roll-frequency
>>>>> (take a look at 3.1.1.  Motivations for the KSK and ZSK Separation,
> the last paragraphs)
>>>>> -
> http://www.nlnetlabs.nl/svn/rfc4641bis/trunk/open-issues/differentiation_trustanchor_parent
>>>>> -
> http://www.nlnetlabs.nl/svn/rfc4641bis/trunk/open-issues/discussion_of_timescales
>>>>> -
> http://www.nlnetlabs.nl/svn/rfc4641bis/trunk/open-issues/non-cooperative-registrars
>>>>> -
> http://www.nlnetlabs.nl/svn/rfc4641bis/trunk/open-issues/rollover_assumptions
>>>>> -
> http://www.nlnetlabs.nl/svn/rfc4641bis/trunk/open-issues/trust_anchor_and_parent_keys
>>>>> I think this issue has become obsolete.
>>>>>
>>>>> Since some of these issues are hard to relate to version 3 of the
> draft I would like to
>>>>> take the following approach for version 4 of the I-D: mark all above
> issues as completed,
>>>>> unless I receive further clarification on why I shouldn't (possibly
> with suggested text),
>>>>> open new issues relative to version 3 of the draft, address those in
> version 4.
>>>>>
>>>>> My target is to have version 4 of the document last call ready. That
> is all major issues out of the way, and only nit-fixing.
>>>>>
>>>>> I am aware of a number of editorial nits[*]
>>>>>
>>>>> --Olaf
>>>>>
>>>>> [*] See http://www.secret-wg.org/draft-ietf-dnsop-rfc4641bis.txt
> for a
> snapshot of the living document and http://tiny.cc/6sllt
>>>>> for the difference between the living document and the draft
> version 3
> as it lives in the repository.
>>>>>
>>>>> ________________________________________________________
>>>>>
>>>>> Olaf M. Kolkman                        NLnet Labs
>>>>>                                        Science Park 140,
>>>>> http://www.nlnetlabs.nl/               1098 XG Amsterdam
>>>>>
>>>>> _______________________________________________
>>>>> DNSOP mailing list
>>>>> [email protected]
>>>>> https://www.ietf.org/mailman/listinfo/dnsop
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