US-based cloud services face censorship from the Chinese government for helping free speech activists access banned websites.
Social media platforms such as Facebook and Twitter, and services like Gmail and news websites are blocked in China, but some tech companies are channelling data through cloud services illegally, according to activists situated outside China.
Services run by providers Amazon, Microsoft and Akamai are all designed to speed up websites, but the alleged misuse of platforms by app developers mean they are being used to bypass firewalls in China.
The method, dubbed 'cloud-cloaking' is delivered via content delivery networks (CDN) provided by companies including Microsoft and Amazon.
An activist can sign up to an account and then link to a blocked website behind it. Those wanting to access the link can download an app that routes them to a mirrored version of the link that is encrypted, so it cannot be tracked.
Darknet browsers such as Lantern, Greatfire.org and Tor are being used to outwit the censors.
Adam Fisk, founder of Lantern, explained what he saw as the activists' strategy to the Wall Street Journal, saying: "Essentially, it’s similar to forcing authoritarian regimes to kill everyone in a protest because they can’t tell the real agitators from the bystanders,” he said.
A number of services have now been blocked in China, including Verizon's Edgecast cloud service that was being exploited by services to help activists access blocked websites.
Other cloud providers are beginning to scale back or stop operations in China in order to protect themselves from being switched off by the government.
Some are now blocking services like Lantern so they cannot be accused of allowing censored content to enter China.
For example, CloudFlare recently blocked the service. Matthew Prince, chief executive of CloudFlare said: "We don’t do anything to thwart the content restrictions in China or other countries. We’re a tech company and we comply with the law.”
