Subject: [perpass] on encryption and social networks (Was Last call: draft-farrell-perpass-attack-02)

From: Eliot Lear <[email-masked]>
Date: Wed, 11 Dec 2013 09:40:42 +0100

Hi Stefan,

On 12/11/13 8:35 AM, Stefan Winter wrote:
> Hi,
>
>>> Knives are easily available to anyone, just like encryption.
>> ...and just like pervasive monitoring?
> That's a very good thought.
>
> Yes, I believe encrpytion and the ability to pervasively monitor are
> both easily available to everyone.
>
> The next step after availability is actual usage, and this is where
> things get interesting.
>
> I believe that where encryption is not actually *used*, pervasice
> monitoring *will* happen. Or, to state it a bit more in a logic-oriented
> way:
>
> Either the use of encryption proliferates, or the use of pervasive
> monitoring proliferates.
>
> It is a strict XOR: you can't have both, and you can't have none of the two.

Pervasive monitoring is not just about encryption, and I suspect you
fully understand this, but have simplified your argument for the
purposes of focusing on encryption.  Even so, I like your analogy, in as
much as you are not looking at one big XOR but many little small ones
and then summing them on either side of the equation.  That's the nature
of engineering tradeoffs, to be fair.

In reviewing some other work on another list, I came across a paper that
talked about pervasive surveillance from an economics sense, written in
2006 entitled /The Economics of Mass Surveillance and the Questionable
Value of Anonymous Communications/.[1]  It's early work to be sure, and
actually argues that the adversary has to actually do very little to
achieve quite a lot in monitoring everyone.  But it also alludes to the
use of social network theory to answer questions of "who" not "what". 
While there are many different aspects of surveillance, social networks
are clearly a component.

Masking the "who" is much harder than the what, and yet the "who" may be
as or more valuable.  Unfortunately for us, the who can be represented
by IP address (as an example).  It's why there's some interest in TOR. 
Fortunately for us, use of services like Google or Facebook or Twitter
provide a means to obscure paths of communication.  Unfortunately for
us, they become single points of failure.[*]

This goes to a point that Mark Nottingham made in the plenary.  How do
we strike a balance between those single points of failure on the one
hand and the potential benefits that some amount of aggregation can
bring?  There has been other related work on this topic from the context
of platform diversity and cybersecurity, but I regret that I couldn't
find the paper I wanted to cite for this email (I tried- it's there-
maybe others can dig it up) that is worth some consideration.

My point in raising this now and my point of intervening several times
in the plenary is to highlight that many of the issues around pervasive
surveillance are complex and have many tradeoffs to be made.  There's
some research to be reviewed, and perhaps some research to be
performed.  When we say that we the IETF are going to do something, we
need to be looking at a long term view, while taking reasonable actions
in the short term that heads us in the right direction.

Eliot

[1] http://weis2006.econinfosec.org/docs/36.pdf
[*] I imagine there's an undiscovered Rogers and Hammerstein song called
"Fortunately/Unfortunately" buried in here.

---

From: Stefan Winter <[email-masked]>
Date: Wed, 11 Dec 2013 11:40:47 +0100

Hi,

> purposes of focusing on encryption.

Well, yes, the thread was massively around encryption (which was
probably off-topic (sorry), as perpass doesn't explicitly touch this).

>  Even so, I like your analogy, in as

I think my main point is that the world at large wasn't aware that there
is an equation at play at all.

For a very long time we (for some definition of we; I suggest "internet
users") thought that when lowering the encryption/privacy/etc. side,
there would be no adverse effect; essentially thinking "Nah, there is
nobody who wants to exploit my not-very-important data, and nobody would
be able to do this on a big scale anyway; we can afford to
ignore/depriorise security properties".

What we've learned from the Snowden documents is that we have to expect
capable adversaries to be at all the important spots who will merrily
exploit any opportunity we give them and make the most out of it. They
even collect our digital junk and find it a valuable asset.

Only at that point did it become clear that there actually *is* an
equation, and that the other side of the equation is an ugly-looking beast.

And by consequence, that any lapse on our side of the equation will have
an effect on the other side.

(To be fair, the equation is of course a lot more complicated than my
simplistic XOR ;-) )

In a way, using the same half-baked mathemetical expression repertoire:

perpass attacks are a function of encryption, authentication, traffic
volume analysis, ...; or:

f(level of use of encrpytion, level of use of anonymity, level of use of
traffic volume concealment, ...) = actual surveillance level

Before Snowden, I would not have put an equals there, but merely:
"presents an upper bound for". I have become less optimistic :-/

We should tune all parameters of the function to minimise the outcome of
the function; under the condition of keeping in mind that the left side
should still remain *usable* with this tuning in place.

> us, they become single points of failure.[*]

Thanks for the link to the paper, a good read! It suggests there's not
just something to be learned from "who" and "what" but also the "how much".

One of the reasons why I jumped on the encryption part of things is
because I consider those to be the low-hanging fruit - it's the "what".

About the what: Developing encryption for protocols is "what we do", so
doing more of that comes easy.

About the who: very exact and deterministic routing of packets to known
IP addresses is what we do. Changing things towards introducing
untracable, indeterministic detours and artificially making
communication less effective by creating noise is not what we usually
do. So working in that area is harder. If we don't mind taking non-IETF
work into our hands we could of course say: every router MUST TOR (both
for outgoing user payload, and as a relay and exit node) - but do we
want that? The implications on traffic volume and routing efficiency are
totally non-obvious.

About the "how much", only a crazy idea: it would be kind of nice to
have a program on every internet user's computer who "keeps the line
busy" at all times. Equipped with a random selection of URLs to visit,
it just downloads stuff and moves it to /dev/null. Just to make the SNR
to a passive listener uninteresting. An external viewer can't determine
if a URL was automated junk download or something the user actually saw.
Such a scheme would make perpass attacks much less useful, all without
encryption. It could even help with plausible deniability in case a
government finds a particularly "bad" URL was visited by the user - it's
quite plausible that it was not him, but some daemon on his machine, and
the user never saw the result of the download. Google has a pretty good
DB of URLs to visit - and it's even largely copyright-infringement
clean, because the copyright holders are nice enough to force Google to
cleanse infringing entries. Thanks!

Greetings,

Stefan Winter

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