Disguising Tor Traffic as Skype Video Calls-Bruce Schneie

April 23, 2012

Bruce Schneier

Crypto-Gram: April 13, 2012

http://www.schneier.com/blog/archives/2012/04/disguising_tor.html

 

One of the problems with Tor traffic is that it can de detected and blocked. Here’s SkypeMorph, a clever system that disguises Tor traffic as Skype video traffic.

To prevent the Tor traffic from being recognized by anyone analyzing the network flow, SkypeMorph uses what’s known as traffic shaping to convert Tor packets into User Datagram Protocol packets, as used by Skype. The traffic shaping also mimics the sizes and timings of packets produced by normal Skype video conversations. As a result, outsiders observing the traffic between the end user and the bridge see data that looks identical to a Skype video conversation.

The SkypeMorph developers chose Skype because the software is widely used throughout the world, making it hard for governments to block it without arousing widespread criticism. The developers picked the VoIP client’s video functions because its flow of packets more closely resembles Tor traffic. Voice communications, by contrast, show long pauses in transmissions, as one party speaks and the other listens.

To receive these entries once a month by e-mail, sign up for the Crypto-Gram Newsletter.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: