SkypeMorph

SkypeMorph is a software implementation designed to to send Tor data over the internet disguised as a Skype video call in order to circumvent internet censorship. The concept was first published in a paper by Hooman Mohajeri Moghaddam, Baiyu Li, Mohammad Derakhshani, and Ian Goldberg from the University of Waterloo in Ontario, Canada in March 2012.
The popularity of using Tor to anonymise internet communications has been considered threat by some governments and is illegal in some countries. Tor traffic can be blocked by governments or corporations either by blocking access to the IP addresses of known Tor hosts and bridges on the internet or the data packets themselves can be identified with deep packet inspection and blocked.
By making use of the Skype API, a client, behind a firewall that blocks Tor traffic, initiates a Skype video call with a Tor bridge on the internet. The Skype connection is then dropped leaving the bridge free to establish further SkypeMorph connections.
The Tor data is then converted into UDP packets and encrypted with the keys generated at initialisation of the Skype video call. These packets are indistinguishable from normal Skype video call packets. The packets are broadcast at intervals that mimic the timing of the data of a video call making the traffic even less likely to be identified as suspicious.
Video calls are preferable to voice calls as the former involves continual transmission of data whereas voice calls are punctuated by silence while the one party is listening to the other speak.
The use of the Skype video call protocol to obfuscate Tor traffic was chosen as the authors of the paper consider this traffic less likely to be blocked without arousing suspicion.

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