Re: [secdir] review of draft-ietf-dnsext-dnssec-gost-05

Stephen Kent <kent@bbn.com> Tue, 09 February 2010 21:10 UTC

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Date: Tue, 9 Feb 2010 16:11:56 -0500
To: Basil Dolmatov <dol@cryptocom.ru>
From: Stephen Kent <kent@bbn.com>
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Cc: Andrew Sullivan <ajs@shinkuro.com>, Ralph Droms <rdroms@cisco.com>, ogud@ogud.com, secdir@ietf.org
Subject: Re: [secdir] review of draft-ietf-dnsext-dnssec-gost-05
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Basil,

Sorry that I seem to have lost your message in my inbox for a while. 
Replies inline below.

>>...
>Yes, we do disagree in principles (see below).
>
>>The question for both DNSSEC and SIDR/RPKI is how many algorithms 
>>relying parties MUST/SHOULD be
>>
>I wondered why MUST and SHOULD are quoted together. I thought that 
>it is two _different_ modal verbs with _different_ meaning and 
>_different_ implementation demands.

SHOULD is MUST with an allowance for "carefully weighed" exceptions. 
Both indicate that a compliant implementation ought to have code that 
supports the referenced feature. In this case, that would be code to 
support GOST algs.

>
>...
>>I believe that the situation for DNESEC is equivalent, i.e., 
>>imposing a requirement (via MUST or SHOULD) to support more than a 
>>current and next set of algorithms is not justifiable.
>>
>The situation in DNSSec is entirely different from SIDR:
>
>>Comparing to DNS the IDR ideology is entirely different: DNS is 
>>wholistic and united service, but main IDR principle is the 
>>independence of routing decisions for any given AS.
>>
>The way that was chosen by SIDR developers is demanding to invent 
>some methods and technologies to prevent network from being split.
>Thank you, Steve, you proposed one of the possible technologies 
>which makes that possible (at least makes a forthcoming split more 
>or less implicit).
>That does not mean that this technology is the _good_ one. It means 
>that for the given set of circumstances this solution is 
>_the_only_possible_ one.

The local TA management capability that I have described for SIDR is 
intended to deal with the general problem of an RP (or a sovereign 
entity) wanting to create and manage a local view of the RPKI.  It is 
not primarily designed to accommodate national algorithms, although 
it can be used for that was well.

>So, I quit the discussion in SIDR, not because of I was satisfied 
>with the technology and solutions, but because of I have understood 
>how I could maintain network interoperability even with this rigid 
>technology and have had more urgent tasks to perform.
>
>I kindly ask to all participating parties do not try to castrate 
>flexible protocol design of DNSSec to the SIDR/RPKI rigid approach.

Oh, "castrate" seems like a pretty harsh term to use :-). Both the 
RPKI and DNSSEC are flexible protocols.  We're debating the issue of 
how broad a set of algorithms MUST/SHOULD be supported by RPs, which 
is an architectural (and political)  issue.

>>It imposes unacceptable costs on resolvers (analogous to RPs in the 
>>RPKI context)
>>
>RPs - are not resolver analogues, but this is for another discussion.

OK.

>>and may have adverse secruity implications. Such externalization of 
>>costs is a fundamentally bad approach, one that the IETF tries to 
>>avoid in analogous contexts in all areas.
>>
>Here is another difference od DNSSec from SIDR - most of the 
>software is open-source in DNSSec, so costs have been already 
>distributed evenly.
>As for proprietary realisations it seems to me the maintaining of 
>the cost/profit balance is the task of the management of the given 
>enterprise, and I am sure that they will do their work well.

We disagree on the nature of how costs may accrue.

>>It is fine for DNSEXT to allocate algorithm IDs to national 
>>algorithms like GOST, but it is not appropriate to mandate their 
>>support, for the reasons cited in my review.
>>
>I do agree that MUST set of algorithms should be very narrow and 
>limited generally speaking to those algorithms by which root zone is 
>signed.

I'm glad we agree on this. Since SHOULD is only a slightly-diminished 
form of MUST, ...

>As for the other algorithms, it seems to me that the main goal of 
>DNS system is the providing integral name service resolution. If one 
>have to perform some additional steps (install different resolver 
>software, include something and something) just to get access to the 
>network names on some part of the world, then the obvious next step 
>will be to point this different resolver to another root of the tree.

Some might interpret this as a threat, even though I'm sure you 
didn't mean it that way.

>Maybe this is the way the DNS system will develop, but now I think 
>that the some effort to keep the DNS system united is justified.

Unified is a goal we both agree upon, but mandated support for 
national algorithms is NOT a unifying principle, it is a Balkanizing 
principle (if you'll pardon the term).

Steve