[tor-talk] Question for those who say "Tor is pwned"

Tue Jun 21 16:29:09 UTC 2016

Thanks for the kind words and support Ted. I always feel funny getting
much credit here when there's so much collaboration and shoulders of
giants and all that.  Not to mention that I just work on making this
stuff. It's the people who use it because they are doing things that
really need it who are making the real contributions to humanity. And
please don't be pained on my account. Generally I don't find it a good
use of my time to respond to the almost ineffable cardinals of
confused/misinformation out there, but there are new people joining
the list all the time. So sometimes I think it's good to try to set the
record straight a bit for those with ears to hear. ( Plus when I'm
avoiding facing that I'll be up all night working on something at the
end of an already long day, it's easy to distract myself with
this. ;>)

aloha,
Paul

On Mon, Jun 20, 2016 at 07:12:31PM -0700, Ted Smith wrote:
> Paul, it pains me to see someone, who has contributed so much to humanity through a long and celebrated career as a scientist, feel the need to engage with what is at worst an agent of some oppressive government hoping to scare people off Tor, and at best a hostile crank.
> 
> As a counterpoint, I'd like to thank you for everything you've contributed, and beg the Tor Project to take better care of its public channels of discourse. Things weren't always this way, and regardless of the motivations of those involved, this behavior is an attack that needs to be defended against. 
> 
> On June 20, 2016 6:25:53 PM PDT, Paul Syverson <paul.syverson at nrl.navy.mil> wrote:
> >On Mon, Jun 20, 2016 at 09:19:27PM -0300, juan wrote:
> >> On Mon, 20 Jun 2016 18:50:10 -0500
> >> Anthony Papillion <anthony at cajuntechie.org> wrote:
> >> 
> >> > -----BEGIN PGP SIGNED MESSAGE-----
> >> > Hash: SHA512
> >> > 
> >> > On 6/20/2016 6:35 PM, juan wrote:
> >> > > On Mon, 20 Jun 2016 18:07:12 -0500 Anthony Papillion
> >> > > <anthony at cajuntechie.org> wrote:
> >> > > 
> >> > > I see a lot of people talking about how Tor is pwned by the US 
> >> > > Government and is insecure 'by design'. I'm assuming that they
> >> > > know this from a thorough analysis of the source code,
> >> > > 
> >> > > 
> >> > >> No. You don't need to look at the source code to know that 
> >> > >> 'people'(the US gov't) who can monitor traffic going into the
> >tor
> >> > >> network and out of it can correlate the traffic and
> >'deanonymize'
> >> > >> users.
> >> > > 
> >> > >> It should also be obvious, for instance, that if an attacker 
> >> > >> happens to control the 3 nodes used to build a circuit, he can 
> >> > >> also 'deanonymize' the user.
> >> > 
> >> > True. However, I'm not sure how that's a 'pwned by design' thing
> >> > (which ascribes malicious intent to the Tor Project). ]
> >> 
> >> 
> >> 	That was an example of stuff you can know about tor without
> >> 	looking at the source code, not necessarily an example of
> >> 	malicious intent.
> >> 
> >> 	What tor designers knew from day zero is that a 'global passive
> >> 	adversary' - that is their boss the US gov't - can simply ignore
> >> 	the routing inside the network and look at the network's edges.
> >
> >
> >I know I'm feeding the troll, but this is just crap. I invented onion
> >routing (with David and Michael) and designed Tor (with Roger and
> >Nick).  We did not design it so that an adversary can just watch the
> >edges. We designed it to separate identification from routing. Nobody
> >told or requested us to make anything weak or less secure. The three
> >of us came up with the motivations and idea for onion routing ourselves
> >and argued for the usefulness of pursuing it further. And we designed
> >it to be as secure as we could and still functional. And, as many have
> >argued, usability and performance are security properties for traffic
> >and routing security systems. Indeed perceived usability and
> >performance are important, as are network and operator
> >incentives. David, Michael and I designed the thing to be secure. We
> >also explained that it needed to carry traffic for others, let others
> >run part of the infrastructure, and be open source for it to provide
> >security to any distinct enterprise or general class wanting to use it
> >to protect their communications. This is part of the security design
> >regardless of who builds, deploys, or uses it. There were onion
> >routing networks, e.g., the Freedom network from Zero Knowledge
> >Systems Inc., that, to the best of my knowledge, had nobody from the
> >U.S. govt. involved in its deployment or design (other than that it
> >was an instance of onion routing). It was designed and built by other
> >people who are wicked smart (smarter than me) and free to create and
> >build whatever they wanted.  Somehow, this is what they chose to make.
> >
> >Some people early on when we were first publicizing and announcing
> >onion routing (e.g. I remember getting such a question at FC'97) asked
> >us why we weren't building pipenet. Such a network is theoretically
> >way more secure for some properties in idealized environments, but
> >even a single user can shut down the network by simply not sending.
> >That's not secure.  In fact the first onion routing design in 95-96
> >was not subject to ready observation at the edges.  (although somebody
> >watching all the links from every onion router to every other could
> >still learn much).  The default configuration assumed onion routers
> >running on enclave firewalls with no separate clients. We explored
> >various padding and similar schemes to complicate observation of
> >traffic patterns, but I have yet to this day to see one that is
> >adequately
> >practical to deploy and effective. These were things to try to add to
> >make the basic design more secure, but we could not find anything to
> >appreciably help here so did not incorporate it into the Tor design.
> >
> >If you ever find such a design, describe it. No credible researcher in
> >any scientific venue has ever claimed to have a system to be more
> >secure that essentially covers the general use case and userbase of
> >Tor.  Mix systems, DC nets, buses, PIR, etc. are all very cool. And
> >subject to some strong environment and other assumptions can be more
> >secure than Tor against some classes of adversaries.  I have worked on
> >and designed some of these cool systems myself. But compared to Tor,
> >each one of these has limitations that, as explored and designed so
> >far, would restrict to a small (hence more easily targeted) anonymity
> >set, or has untenable usability or performance problems, or generally
> >all of the above.  It's funny that there's supposed to be this
> >intentional built in design weakness, and yet no scientist, engineer,
> >or mathematician in any country seems to have published a stronger
> >fundamental design. Hmm, perhaps you mean to imply that we who created
> >onion routing not only intentionally designed our systems to be weaker
> >than we could have but that we also have controlled all of the
> >scientific research and publication on secure system design by every
> >researcher in every country everywhere on the planet for the last
> >twenty years.
> >
> >Onion routing design has evolved. Tor has forward secrecy, which the
> >two main onion routing designs we introduced before it did not. (Nor
> >did the Freedom network.) But we did not come up with including
> >forward secrecy, that was first introduced in Zack Brown's
> >Cebolla. And we adopted it when we designed Tor. Tor added a directory
> >system after its first design, then evolved and improved design,
> >robustness, and trust diffusion of the directory system over time. Tor
> >added deterministic builds to further reduce the trust in Tor-built
> >binaries, and work to improve continues through this day.
> >
> >We have been completely forthcoming about our designs and any
> >limitations found by ourselves or others, including everything we can
> >empirically discern about end-to-end correlation risks from ASes,
> >IXPs, MLATs, etc.  And we have always designed to be as secure as we
> >practically could. I'm not going to engage further. I do invite those
> >who might so engage to find any valid technical, empirically justified
> >stronger design that does not make significant compromises to
> >performance, cut off large chunks of the existing userbase, etc. I'm
> >dubious you will find any. But if you do, I'd be happy to pursue its
> >development.
> >
> >aloha,
> >Paul
> >
> >[snip]
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