Re: [Pearg] About hiding in crowds

Eliot Lear <> Tue, 11 August 2020 10:00 UTC

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From: Eliot Lear <>
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Date: Tue, 11 Aug 2020 12:00:22 +0200
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To: Christian Huitema <>
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Subject: Re: [Pearg] About hiding in crowds
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Hi Christian

What you describe below is something that Barbara Fraser and I noted some years ago at the STRINT workshop.  We argued at the time that providing points in the network to aggregate traffic was an appropriate approach to both blend and blind.  It requires end user trust in those aggregation points that some might call middle boxes.  This is effectively what Mozilla has done with Cloudflare.  This notion of agency is still something that I think is worth exploring.


> On 11 Aug 2020, at 01:24, Christian Huitema <> wrote:
> Signed PGP part
> A lot of the privacy extensions recently developed amount to "hiding in
> crowds". For example, SNI encryption assumes that multiple servers are
> accessible through the same IP address. If the SNI is hidden, outside
> observers won't know which one was accessed. DNS encryption makes the
> same assumption in an indirect way. It assumes that we gain privacy by
> hiding the DNS exchange that maps to an IP address. This
> is fine, except for the fact that most servers have their own IP
> address. You can hide the DNS exchange, you can hide the SNI, but
> outside observers will still be able to understand which servers you are
> accessing by simply looking at the address header. If we want real
> privacy, we will need something else!
> How do I know? I started with the Majestic Million list of domain names,
> and resolved 25,000 of these names, and found out that on average a
> given IP address was shared by about 1.21 names, as explained in:
> And then I resolved the next 25000 names to be more sure of the results.
> The average increased slightly, from 1.21 to 1.22, which does not change
> the results much. 74.6% of domains use an address that is unique to
> them, 8.7% use an address shared by 2 domains, and only 8% use an
> address shared by 10 or more servers. DNS encryption and SNI encryption
> do bring privacy for a minority of connection, for which it may well be
> important. But they do not improve privacy in 75% of the cases.
> I understand that privacy-warriors can use VPN, proxies or Tor. But
> these tools are far from perfect -- see the recent Sybil attacks against
> Tor, or the outveiling of shady business practices by many VPNs. In any
> case, these tools at best provide "privacy for a few active users". But
> that leaves aside the bulk of Internet users. Thus my question for this
> program: how would we provide privacy for the masses?
> -- Christian Huitema