Curious to hear your thoughts on this:
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With the threat of powerful intelligence agencies, like the NSA, looming
large, researchers have built a new Tor client called Astoria designed
specifically to make eavesdropping harder for the world's richest,
most aggressive, and most capable spies.
Tor, the world’s most popular anonymity network, works like
this: A user fires up the client and connects to the network
through what's called an entry node. To reach a website
anonymously, the user’s Internet traffic is then passed encrypted
through a so-called middle relay and then an exit relay (and back
again). That user-relay connection is called a circuit. The
website on the receiving end doesn’t know who is visiting, only
that a faceless Tor user has connected. An
eavesdropper shouldn’t be able to know who the Tor user is either,
thanks to the encrypted traffic being routed through 6,000 nodes
in the network. But something called "timing
attacks" change the situation. When an adversary takes control of
both the entry and exit relays, research shows they can
potentially deanonymize Tor users within minutes.
A full 58 percent of Tor circuits are vulnerable to
network-level attackers, such as the NSA or Britain’s Government
Communications Headquarters (GCHQ), when they access popular
websites, according to new research from
American and Israeli academics. Chinese users are the most
vulnerable of all to these kinds of attacks, with researchers
finding 85.7 percent of all Tor circuits from the country to be
vulnerable.
Even though Tor is designed to provide complete anonymity to
its users, the NSA’s position means they can potentially see and
measure both traffic entering the Tor network and the traffic that
comes out. When an intelligence agency can see both,simple statistics help an autonomous
system at their control match the data up in a timing attack and
discover the identity of the sender. Anonymity
over. This kind of threat has been known to Tor
developers for over a decade. They’ve been trying to make
eavesdropping difficult for spy agencies for just as long.
To counter the threat, American-Israeli researchers built
Astoria, a new Tor client focused on defeating autonomous systems
that can break Tor’s anonymity. Astoria reduces the
number of vulnerable circuits from 58 percent to 5.8 percent, the
researchers say. The new solution is the first designed to beat
even the most recently proposed asymmetric
correlation attacks on Tor.
Designed to beat such attacks, Astoria differs most
significantly from Tor's default client in how it selects the
circuits that connect a user to the network and then to the
outside Internet. The tool, at its foundation, is an algorithm
designed to more accurately predict attacks and then securely
select relays that mitigate timing attack opportunities for
top-tier adversaries.
Astoria adroitly considers how circuits should, according to
the researchers, be made “when there are no safe possibilities,”
how to safely balance the growing bandwidth load across the Tor
network, and how to keep Tor’s performance “reasonable” and
relatively fast even when Astoria is in its most secure
configuration. All this while under the unblinking
gaze of the world’s best intel services. Defeating
timing attacks against Tor completely isn’t possible because of
how Tor is built, but making the attacks more costly and less
likely to succeed is a pastime that Tor developers have dedicated
a decade to. Astoria follows in those footsteps. By
choosing relays based on lowering the threat of eavesdropping by
autonomous systems and then choosing randomly if no safe passage
is possible, Astoria aims to minimize the information gained by an
adversary watching an entire circuit.
“In addition to providing high-levels of security against
such attacks, Astoria also has performance that is within a
reasonable distance from the current Tor client,” the researchers
wrote. “Unlike other AS-aware Tor clients, Astoria also considers
how circuits should be built in the worst case—i.e., when there
are no safe relays that are available. Further, Astoria is a good
network citizen and works to ensure that the all circuits created
by it are load-balanced across the volunteer driven Tor network.”
In an upgrade aimed at making Tor even more usable for the
average person, the newest Tor Browser allows a sliding scale of
security that balances speed and usability with strong security
preferences. Similarly, Astoria provides multiple
security options. However, it's both most effective and most
usable when at its highest security level, the researchers say, so
"Astoria is a usable substitute for the vanilla Tor client only in
scenarios where security is a high priority."
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Source:
http://www.dailydot.com/politics/tor-astoria-timing-attack-client/