Re: [dnsext] Clarifying the mandatory algorithm rules

Edward Lewis <Ed.Lewis@neustar.biz> Fri, 11 March 2011 13:40 UTC

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References: <alpine.BSF.2.00.1011180553250.83352@fledge.watson.org> <4CE51293.5040605@nlnetlabs.nl> <a06240801c9101620d463@[192.168.128.163]> <22284.1290447209@nsa.vix.com> <4CF4D54B.5000407@nlnetlabs.nl><alpine.BSF.2.00.1103100812260.60284@fledge .watson.org> <20110310223438.978E9C0E902@drugs.dv.isc.org> <4D79DDFA.3010006@nlnetlabs.nl>
Date: Fri, 11 Mar 2011 08:34:57 -0500
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From: Edward Lewis <Ed.Lewis@neustar.biz>
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Subject: Re: [dnsext] Clarifying the mandatory algorithm rules
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"Could" as in, SHOULD NOT if I had to choose from the 2119 menu of 
options.  I'd prefer "not recommended" but that isn't on the menu.  I 
would prefer to use this bon mot: "I encourage my competitors to 
behave this way."

...to be clear, I am talking about the validator actually checking 
the signatures.  Having the ability to, sure, that is important.  But 
"if one chain works, it succeeds" is an important spirit.

At 9:31 +0100 3/11/11, Matthijs Mekking wrote:
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>
>Hi,
>
>On November 30, Wouter acknowledges that changes need to be made to the
>Unbound implementation and asks for guidance:
>
>   http://www.ietf.org/mail-archive/web/dnsext/current/msg10115.html
>
>Presenting two options:
>* One signature is enough (the lenient way)
>* Check the algorithms.
>
>But when checking the algorithms, thou should not use the DNSKEY RRset,
>but the DS RRset.
>
>I think the general consensus is that a validator should at least be
>able to check the algorithms in the DS RRset (Please correct me if I am
>being to hasty in my conclusion). There is still debate whether the
>validator SHOULD or MAY do this (Ed Lewis argued the term 'could', I
>think that translates to the RFC2119 term MAY).
>
>  Proposed text would then be:
>
>   "The validator SHOULD or MAY check (choice here) that the algorithms
>    signaled in the DS-set work (but only for algorithms supported by
>    the validator, of course)."
>
>Best regards,
>
>Matthijs
>
>
>
>
>On 03/10/2011 11:34 PM, Mark Andrews wrote:
>>
>>  In message 
>><alpine.BSF.2.00.1103100812260.60284@fledge.watson.org>tson.org>, Samuel Weil
>>  er writes:
>>>  On Tue, 30 Nov 2010, W.C.A. Wijngaards wrote:
>>>
>>>>  It is clear that checking the set of algorithms present in the DNSKEY
>>>>  set is not a good idea, and checking the set of algorithms from the DS
>>>>  set is the right, more lenient way to go.
>>>
>>>  I apologize for checking out of this discussion last fall.
>>>
>>>  I would like the WG's help understanding where you want to go with
>>>  this topic.  I don't fully understand the argument in favor of not
>>>  checking the algorithms on the child side of the zone cut (= the ones
>>>  in the DNSKEY RRset), nor am I sure that was the direction everyone
>>>  seemed to want to go.  Could someone summarize the current state of
>>>  this?
>>>
>>>  My own inclination is (still) to treat this as a clarification, saying
>>>  that validators are not required to enforce these rules.  (In other
>>>  words, the extra checks Unbound did were just fine, though
>>>  unnecessary.  BIND's lenient approach was also fine.)  Two specific
>>>  pieces of proposed text can be found in the first message in this
>>>  thread, dated 18 November 2010.
>>
>>  While we think about this ISC has also had bug reports claiming
>>  that is we don't publish DNSKEY prior to signing with them we are
>>  break RFC 4035 because it allows verification of every RRSIG as a
>>  policy and the only way to do that is to publish the DNSKEY prior
>>  to use.
>>
>>     If other RRSIG RRs also cover this RRset, the local resolver security
>>     policy determines whether the resolver also has to test these RRSIG
>>     RRs and how to resolve conflicts if these RRSIG RRs lead to differing
>>     results.
>>
>>>  -- Sam
>>>  _______________________________________________
>>>  dnsext mailing list
>>>  dnsext@ietf.org
>>>  https://www.ietf.org/mailman/listinfo/dnsext
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Edward Lewis
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