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posted by martyb on Saturday May 23 2015, @06:55PM   Printer-friendly
from the peeling-the-layers dept.

American and Israeli academics have created Astoria, a new Tor client designed to defeat the latest traffic analysis techniques used to surveil the network:

Astoria all-but decimates the number of vulnerable connections on the Tor network, bringing the figure from 58 per cent of total users to 5.8 per cent, the researchers claim. Astoria hopes to utilise a new relay-selection algorithm which would prevent the asymmetric connections which make traffic analysis possible.

Due to the large amounts of processing power needed to analyse the data passing through the Tor network, traffic analysis is only conceivable as a de-anonymising attack when it is launched by state actors, such as those in the Five Eyes surveillance alliance. Steven J. Murdoch, who along with George Danezis published a paper on the Low-Cost Traffic Analysis of Tor [PDF] back in 2005, told The Register that "Traffic-analysis is quite a sophisticated surveillance technique, but one which intelligence agencies have extensive experience in. With enough computation power, access to communication links and expertise, traffic analysis will be able to de-anonymize the user of any low-latency anonymous communication system, including Tor."

The new work by the researchers' explains how the traffic-analysis attacks may be implemented by any autonomous system (AS) that lies on both the path from the Tor client to the entry relay and the path from the exit relay to the destination. "Previous studies have demonstrated the potential for this type of attack and have proposed relay selection strategies to avoid common ASes (potential attackers) that may perform them. However, recent work has shown that these strategies perform poorly in practice," said the paper [PDF].

Observing that "vanilla" Tor will often select paths that may be subject to an adversary that exploits asymmetric network paths for the sake of analysis, the researchers have said that they "seek to design a relay selection algorithm to mitigate the opportunities for such attackers".

"We design our relay selection system, Astoria, based on the idea of stochastic relay selection. This works by having the Tor client generate a probability distribution that minimizes the chance of attack over all possible relay selection choices, and selecting an entry and exit-relay based on this distribution."

Astoria is not available for download... yet. Discussion at Hacker News.

 
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  • (Score: 2, Interesting) by MichaelDavidCrawford on Saturday May 23 2015, @08:07PM

    by MichaelDavidCrawford (2339) Subscriber Badge <mdcrawford@gmail.com> on Saturday May 23 2015, @08:07PM (#186948) Homepage Journal

    there is an add-on that does searches like "terrorism", "explosives" and so on. That's helpful.

    What I'm thinking of is a program - it doesn't have to be an add-on - that visits https websites. It could work as a crawler. It shouldn't go from link to link any faster than a human web surfer. It would need the same user-agent string as your real browser so maybe an add-on is better.

    --
    Yes I Have No Bananas. [gofundme.com]
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