Re: [DNSOP] DNSOPI-D Action: draft-ietf-dnsop-nsec3-guidance-02.txt

Vladimír Čunát <> Fri, 26 November 2021 10:49 UTC

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To: Petr Špaček <>,
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Subject: Re: [DNSOP] DNSOPI-D Action: draft-ietf-dnsop-nsec3-guidance-02.txt
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On 25/11/2021 13.00, Petr Špaček wrote:
> IMHO in the context of NSEC3 the salt would make sense _only_ if it 
> were rotated faster than attacker was able to walk the zone. Once 
> attacker has list of hashes available for offline cracking the salt 
> does not do anything useful anymore. 

I disagree; you don't need to rotate so fast.  At a moment when a 
particular salt won't be contained in future answers, there's no point 
in creating a dictionary anymore as it's cheaper to crack the gathered 
hashes individually.  The only value of dictionary is (possibly) 
speeding up attacks on names that will appear in future - and the only 
value in re-salting is in making this technique more expensive.  
Resalting interval is the period when a particular dictionary is useful, 
so basically by halving the interval you double the price of this.  [all