There’s been quite a media buzz in the last few days regarding the ability of Amazon’s new 3G Kindle to bypass China’s Great Firewall. I was recently interviewed on BBC World News about how the Kindle does this, and what some of the implications are. As I had about two minutes to put that across in the interview, I’ll expand slightly on the story here.
In brief, the latest generation of Amazon’s Kindle has a web browser along with its free integrated 3G connection. The Kindle isn’t officially available in China, but is easy to find on the grey market and is apparently quite popular. One user recently noticed that browsing to blocked websites, such as Twitter and Facebook, appears to bypass the firewall.
Why does this work? When I heard the story I had an immediate suspicion, and a quick play with my own Kindle confirmed the answer. Amazon have, apparently unintentionally, implemented a common anti-censorship technology in the way that the Kindle handles web requests: it bounces its connection through a proxy server located outside of the censorship zone.
The Kindle is mainly designed to download books from Amazon via their Whispernet service. It appears that when you browse the web, the same connection is used; rather than connecting directly to website, you connect to Amazon’s servers first, which then forward the request to the website.
The result of this is that the Great Firewall, and presumably any national filter such as those implemented in Turkey, only see a perfectly legitimate connection to Amazon. This approach is very similar to that used by Tor, Psiphon and other intentionally censorship-resistant systems.
How easy would this system be to block? Given that the Kindle is not officially available in China, the simplest and most cost-effective approach would seem to be blocking access to the entire Whispernet network. This would prevent legitimate Kindle users from accessing the system in China, but that hardly seems a great concern from China’s point of view.
Another approach would be for China to request that Amazon route all Whispernet connections originating in China through a server behind the Great Firewall. Requiring Amazon to filter requests themselves according to a list provided by the Chinese government would also be possible, but seems an unnecessarily complicated approach.
Enforced filtering, along with a number of other factors, eventually caused Google to leave the Chinese market. It seems unlikely that Amazon would be quite so willing to leave if forced into a similar situation. Google, at their best, were a relatively small presence on the Chinese Internet alongside major players such as Baidu. Amazon, however, through amazon.cn have a much more significant presence, and investment, in the Chinese market.
Realistically, however, China are unlikely to invest significant effort in blocking the Kindle. Despite reports of its popularity the device is not on general sale, and the numbers sold currently seem to be in the low thousands. With a population of over 1.3 billion, there are much more significant targets.
Practically speaking, the Kindle is also expensive in Chinese terms. Searching on taobao.com, China’s equivalent to eBay, shows Kindle 3G prices around 1,099RMB (around £105 or $165), which is out of the range of most Chinese. Additionally, the Kindle’s e-ink screen is monochrome and slow to refresh, making it unsuitable for normal web browsing. Compared with direct anti-censorship technologies, such as Tor or Psiphon, running on a standard PC, the Kindle is very much a poor third option.
Censorship, such as that in China, is most important through its effects on the society as a whole, where access is blocked to the vast majority of the general populace. It would be futile, and ultimately unnecessary, for the Chinese government to expect their system to be absolutely effective. Whether the Chinese government, or indeed any government that engages in broad-scale filtering, would share that viewpoint is another matter. Regardless, blocking the Kindle seems unlikely to be high on the list of priorities.
One potential risk to Amazon is how effectively they restrict access to Whispernet for non-Kindle users. If it were feasible for a normal user to proxy their web requests via Whispernet then it would provide a significant and, presumably, high capacity uncensored relay. In that, perhaps unlikely, scenario Amazon could find themselves in the unenviable position of unwittingly providing corporate sponsorship to anti-censorship activists all over the world. If that were to happen it is almost certain that both China and Amazon would take much more significant notice of this technical curiosity.
In a wider sense, this discovery highlights just how difficult it is to control absolutely the flow of information. China’s firewall is a massive engineering project, and is largely successful in its goals of regulating the content available to the Chinese public. That the Kindle has, entirely by accident, bypassed such a well-funded and pervasive government-level system is worrying for the designers of such systems, and encouraging for those that oppose them.
The Great Firewall of China is officially referred to as the “金盾工程” (jīndùn gōngchéng), or “Golden Shield” within China.