[FoRK] [liberationtech] PRISM vs Tor | The Tor Blog

Eugen Leitl eugen at leitl.org
Mon Jun 10 10:16:23 PDT 2013


----- Forwarded message from Yosem Companys <companys at stanford.edu> -----

Date: Mon, 10 Jun 2013 10:13:50 -0700
From: Yosem Companys <companys at stanford.edu>
To: Liberation Technologies <liberationtech at lists.stanford.edu>
Subject: [liberationtech] PRISM vs Tor | The Tor Blog
Reply-To: liberationtech <liberationtech at lists.stanford.edu>

https://blog.torproject.org/blog/prism-vs-tor

By now, just about everybody has heard about the PRISM surveillance
program, and many are beginning to speculate on its impact on Tor.

Unfortunately, there still are a lot of gaps to fill in terms of
understanding what is really going on, especially in the face of
conflicting information between the primary source material and
Google, Facebook, and Apple's claims of non-involvement.

This apparent conflict means that it is still hard to pin down exactly
how the program impacts Tor, and is leading many to assume worst-case
scenarios.

For example, some of the worst-case scenarios include the NSA using
weaponized exploits to compromise datacenter equipment at these firms.
Less severe, but still extremely worrying possibilities include
issuing gag orders to mid or low-level datacenter staff to install
backdoors or monitoring equipment without any interaction what-so-ever
with the legal and executive staff of the firms themselves.

We're going to save analysis of those speculative and invasive
scenarios for when more information becomes available (though we may
independently write a future blog post onthe dangers of the government
use of weaponized exploits).

For now, let's review what Tor can do, what tools go well with Tor to
give you defense-in-depth for your communications, and what work needs
to be done so we can make it easier to protect communications from
instances where the existing centralized communications infrastructure
is compromised by the NSA, China, Iran, or by anyone else who manages
to get ahold of the keys to the kingdom.


The core Tor software's job is to conceal your identity from your
recipient, and to conceal your recipient and your content from
observers on your end. By itself, Tor does not protect the actual
communications content once it leaves the Tor network. This can make
it useful against some forms of metadata analysis, but this also means
Tor is best used in combination with other tools.

Through the use of HTTPS-Everywhere in Tor Browser, in many cases we
can protect your communications content where parts of the Tor network
and/or your recipients' infrastructure are compromised or under
surveillance. The EFF has created an excellent interactive graphic to
help illustrate and clarify these combined properties.

Through the use of combinations of additional software like TorBirdy
and Enigmail, OTR, and Diaspora, Tor can also protect your
communications content in cases where the communications
infrastructure (Google/Facebook) is compromised.


However, the real interesting use cases for Tor in the face of dragnet
surveillance like this is not that Tor can protect your gmail/facebook
accounts from analysis (in fact, Tor could never really protect
account usage metadata), but that Tor and hidden services are actually
a key building block to build systems where it is no longer possible
to go to a single party and obtain the full metadata, communications
frequency, *or* contents.

Tor hidden services are arbitrary communications endpoints that are
resistant to both metadata analysis and surveillance.

A simple (to deploy) example of a hidden service based mechanism to
significantly hinder exactly this type of surveillance is an XMPP
client that also ships with an XMPP server and a Tor hidden service.
Such a P2P communication system (where the clients are themselves the
servers) is both end-to-end secure, and does *not* have a single
central server where metadata is available. This communication is
private, pseudonymous, and does not have involve any single central
party or intermediary.

More complex examples would include the use of Diaspora and other
decentralized social network protocols with hidden service endpoints.


Despite these compelling use cases and powerful tool combination
possibilities, the Tor Project is under no illusion that these more
sophisticated configurations are easy, usable, or accessible by the
general public.

We recognize that a lot of work needs to be done even for the basic
tools like Tor Browser, TorBirdy, EnigMail, and OTR to work seamlessly
and securely for most users, let alone complex combinations like XMPP
or Diaspora with Hidden Services.

Additionally, hidden services themselves are in need of quite a bit of
development assistance just to maintain their originally designed
level of security, let alone scaling to support large numbers of
endpoints.

Being an Open Source project with limited resources, we welcome
contributions from the community to make any of this software work
better with Tor, or to help improve the Tor software itself.

If you're not a developer, but you would still like to help us succeed
in our mission of securing the world's communications, please donate!
It is a rather big job, after all.


We will keep you updated as we learn more about the exact capabilities
of this program.
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