New software to access blocked websites

The system, called Telex, is the brainchild of computer scientists at the Universities of Michigan (US) and Waterloo, Canada.

"Repressive governments have responded by aggressively filtering internet... we can give more people the ability to take part in free speech and access to information," says J. Alex Halderman, one of the Telex developers.

"It would likely require support from nations that are friendly to the cause of a free and open internet," Halderman said.

Today's anti-censorship schemes make users bypass blocks by routing them through an outside server called a proxy. But the censor can monitor the content of traffic on the whole network and eventually finds and blocks the proxy too, according to a Michigan statement.

Here's how Telex works.

Users can install Telex software. Halderman envisions they could download it from an intermittently available website or borrow a copy from a friend. Internet Service Providers (ISPs) outside the censoring nation would deploy equipment called Telex stations.
When a user wants to visit a blacklisted site, he or she would establish a secure connection to a website, which could be by any password-protected site that isn't blocked. This is a decoy connection.

The Telex software would mark the connection as a Telex request by inserting a secret-coded tag into the page headers. The tag utilizes a cryptographic or hidden technique called "public-key steganography."

The user's request would pass through routers at various ISPs, some of which would be Telex stations. They would hold a private key that lets them recognize tagged connections from Telex clients.

The stations would divert the connections so that the user could get to any site on the internet. Under this system, large segments of the internet would need to be involved through participating ISPs.

These findings will be presented Friday at the USENIX Security Symposium in San Francisco.

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