Telex to help defeat web censors

Developed by US computer scientists the software, called Telex, hides data from banned websites inside traffic from sites deemed safe.

The software draws on well-known encryption techniques to conceal data making it hard to decipher.

So far, Telex is only a prototype but in tests it has been able to defeat Chinese web filters.

Outside in

Telex was developed to get around the problem that stops other anti-censorship technologies being more effective, said Dr Alex Halderman, one of the four-strong team that has worked on Telex since early 2010.

Many existing anti-censorship systems involve connecting to a server or network outside the country in which a user lives.

This approach relies on spreading information about these servers and networks widely enough that citizens hear about them but not so much that censors can find out and block them.

Telex turns this approach on its head, said Dr Halderman.

“Instead of having some server outside the network that’s participating we are doing it in the core of the network,” he said.

Telex exploits the fact that few net-censoring nations block all access and most are happy to let citizens visit a select number of sites regarded as safe.

When a user wants to visit a banned site they initially point their web browser at a safe site. As they connect, Telex software installed on their PC puts a tag or marker on the datastream being sent to that safe destination.

Net routers outside the country recognise that the datastream has been marked and re-direct a request to a banned site. Data from censored webpages is piped back to the user in a datastream disguised to resemble that from safe sites.

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