Daily Archives: March 12, 2015

IMAGE:Sebastian Meiser and Esfandiar Mohammadi provide guarantees of users' anonymity within the Tor network. view more

Credit: Oliver Dietze

This news release is available in German.

Anonymity on the Internet is possible only up to a certain degree. Therefore, it is possible that others may see who is visiting an online advice site on sexual abuse, or who frequently looks up information about a certain disease, for example. Seeing that this kind of private information can be linked to their identity, users will often resort to special online anonymization services. One of the most popular tools is Tor. Since the beginning of the year, alone more than two million users have used it to anonymize their Internet connection data. These services will not only conceal browsing behavior, but also the identity of the user, and that of any other recipients. These will usually be other websites, but could also be another person. Tor works in a way that allows users to establish a connection that is then upheld through its own network. The Tor network comprises up to 6,000 servers, mostly run by volunteers, which computer scientists refer to as "nodes". And since every node only receives the minimal amount of data necessary to relay the information in question, it becomes far more difficult to de-anonymize both the transmitter and the recipient of the data.

"The Tor network isn't perfect, however," says Esfandiar Mohammadi, a researcher at the Research Center for IT Security, CISPA, and a doctoral candidate at the Graduate School for Computer Science in Saarbrcken. "For one, unanticipated attacks at a network level can endanger anonymity. Also, the degree of anonymity the network achieves is highly variable, since volunteers don't necessarily operate their nodes continually or regularly," says Mohammadi.

In collaboration with CISPA researcher Sebastian Meiser, who is also a postgraduate at the Saarbrcken Graduate School for Computer Science, Mohammadi developed a program that can provide an accurate assessment of the level of anonymity an individual user achieves, even while basing the estimate on the fluctuations of the Tor network. According to the researchers, this feature is a worldwide first.

"An attacker that compromises Tor servers can derive the identity of a user with a certain probability. This is exactly what our system calculates," Sebastian Meiser explains. The two Saarbrcken researchers based their technique, which they named "MATor", on a mathematical model that they extended to include different categories of possible attacks. "In order to indicate the probability of de-anonymization, our program performs its calculations using data that is aggregated once an hour and published on the network immediately. MATor also takes the specifics of the respective Internet connection into account, as well as the individual configurations of the Tor software," Meiser says. This feature is also intended as a basis for a so-called plugin, a small extension program for the software "Tor Browser" that the researchers now want to develop. Integrated into the Tor software, this could run in the background and simply notify users as soon as their connection became too unsafe.

Computer science and informatics at Saarland University

The Department of Computer Science forms the core of the informatics landscape at Saarland University. A further seven internationally renowned research institutes are located in the immediate vicinity on campus. As well as the two Max Planck Institutes for Informatics and for Software Systems, the Saarbrcken campus is also home to the German Research Center for Artificial Intelligence, the Intel Visual Computing Institute, the Center for IT Security, Privacy and Accountability (CISPA) and the Cluster of Excellence 'Multimodal Computing and Interaction'.

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Read more:
Cebit 2015: Saarland computer scientists present guarantees for online anonymity

The now-defunct Silk Road site, with drugs for sale (AP)

But what is actually on the dark net? Despite all this noise, relatively little is known. It is, of course, incredibly difficult to research. What we do know is that 2.5 million people use the Tor Browser each day. Tor can be used to browse anything online, and is much-used by civil liberties activists, journalists, and suprisise surprise law enforcement themselves. A decent fraction use Tor to get into the dark net, where there are an estimated 60 thousand or so websites an uncensored blend of the good, the bad, and the very very ugly.

The busiest sites on the dark net are probably the notorious and numerous anonymous markets. Here, anything can be bought and sold: class A narcotics ordered with a click, paid for with the crypto-currency Bitcoin, and delivered direct to your home. For my book, The Dark Net, I spent a lot of time on these sites, trying to work out how and why they worked and even going through the process of buying a small amount of cannabis from one known as Silk Road 2.0.

It turns out the key to their success is not clever encryption, or Bitcoin, or even Tor. It's good old-fashioned customer service. Every visitor to the site, after using his or her drug, leaves a piece of written feedback about the gear and gives a score out of 5. It's a little surreal, but users take it pretty seriously, because it creates the genuinely informed competition and choice which keeps the market ticking over:

Decent coke at a reasonable price. Stealthy packaging. 5/5

First order was lost...I got a reship and now im very happy...Heaven is one of the best dealers on the road!!! Very friendly and good communication too. I will be back soon 😉 5/5

Excerpt from:
What 'dark net' drug buyers say about their dealers

Anonymity on the Internet is possible only up to a certain degree. Therefore, it is possible that others may see who is visiting an online advice site on sexual abuse, or who frequently looks up information about a certain disease, for example. Seeing that this kind of private information can be linked to their identity, users will often resort to special online anonymization services.

One of the most popular tools is Tor. Since the beginning of the year, alone more than two million users have used it to anonymize their Internet connection data. These services will not only conceal browsing behavior, but also the identity of the user, and that of any other recipients. These will usually be other websites, but could also be another person. Tor works in a way that allows users to establish a connection that is then upheld through its own network. The Tor network comprises up to 6,000 servers, mostly run by volunteers, which computer scientists refer to as "nodes." And since every node only receives the minimal amount of data necessary to relay the information in question, it becomes far more difficult to de-anonymize both the transmitter and the recipient of the data.

"The Tor network isn't perfect, however," says Esfandiar Mohammadi, a researcher at the Research Center for IT Security, CISPA, and a doctoral candidate at the Graduate School for Computer Science in Saarbrcken. "For one, unanticipated attacks at a network level can endanger anonymity. Also, the degree of anonymity the network achieves is highly variable, since volunteers don't necessarily operate their nodes continually or regularly," says Mohammadi.

In collaboration with CISPA researcher Sebastian Meiser, who is also a postgraduate at the Saarbrcken Graduate School for Computer Science, Mohammadi developed a program that can provide an accurate assessment of the level of anonymity an individual user achieves, even while basing the estimate on the fluctuations of the Tor network. According to the researchers, this feature is a worldwide first.

"An attacker that compromises Tor servers can derive the identity of a user with a certain probability. This is exactly what our system calculates," Sebastian Meiser explains. The two Saarbrcken researchers based their technique, which they named "MATor," on a mathematical model that they extended to include different categories of possible attacks. "In order to indicate the probability of de-anonymization, our program performs its calculations using data that is aggregated once an hour and published on the network immediately. MATor also takes the specifics of the respective Internet connection into account, as well as the individual configurations of the Tor software," Meiser says. This feature is also intended as a basis for a so-called plugin, a small extension program for the software "Tor Browser" that the researchers now want to develop. Integrated into the Tor software, this could run in the background and simply notify users as soon as their connection became too unsafe.

Story Source:

The above story is based on materials provided by University Saarland. Note: Materials may be edited for content and length.

See original here:
Guarantees for online anonymity?