Subject: Re: [Bitcoin-development] bitcoin DNS addresses

From: phantomcircuit <[email-masked]>
Date: Tue, 26 Jul 2011 18:32:17 +0200

dns resolution is far simpler to implement than properly checking the https certificate chain

Matt Corallo <[email-masked]> wrote:

>For some reason my mail client is being thick and not responding
>on-list, sorry about that...
>
>On Tue, 2011-07-26 at 08:34 -0700, Rick Wesson wrote:
>> > Most OSes dont do any resolving at all, they just query upstream
>> > resolvers.  In the case of the coffee shop, that upstream resolver is
>> > the attacker.  This attacker can easily just claim that the zone you
>> > requested is not DNSSEC signed and return their data and the OS will not
>> > be any wiser.  AFAIK, most OSes dont have a mechanism to require the
>> > zone queried is DNSSEC signed meaning you have to implement a full DNS
>> > resolver in Bitcoin in order for it to be secure.
>> 
>> Matt,
>> 
>> The same attack can apply to https with a self signed cert where it is
>> the A record that is replaced by the attacker and the https request is
>> sent to evil.com's server which responds to the request with an answer
>> in the form you expect. This is what lots of malware does on windows
>> to steel bank login credentials, securing http doesn't prevent such an
>> attack.
>If you are using a self-signed cert to do any kind of important data
>transfer you are just being stupid.  Here I am assuming your computer
>isnt actually compromised, but only the network is, which I think is a
>fairly good assumption.
>> 
>> Windows has supported DNSSEC since 2008 as have most of the unix
>> variants, mac osx since 10.3 Android also seems to include DNSSEC
>> capable resolvers.
>> 
>> If this thread is really about DNSSEC then we might move it to a more
>> appropriate forum for discussing how applications leverage DNS
>> security extensions.  Its taken some years to get the specs done and
>> the root signed I expect it to take many more to enable the
>> applications to leverage the deployed infrastructure.
>No, DNSSEC is very well done, this thread is specifically about the
>security implications of using DNSSEC for Bitcoin address communication.
>IMO it is not a good idea, as for it to be secure against a coffee-shop
>network MITMer you have to implement a full resolver with root trust
>anchors and knowledge of root servers in Bitcoin, which does not seem
>like a good idea.
>> 
>> I am interested in working on the issues surrounding usability and I
>> find that remembering and communicating a bitcoin address are current
>> limiting factors in the acceptance and deployment of this software. My
>> goal is for simpler user experience.
>I totally agree, however I don't think DNS-based resolving is a good
>idea here.  HTTPS does have several advantages over a DNSSEC-based
>solution without any significant drawbacks that I can see.
>
>Matt
>
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