It looks like China is continuing to set the gold standard for internet censorship. For a long time, the Great Firewall has been actively censoring content based on keywords. Activists and dissidents have worked around this filtering by placing text in images, but that doesn't appear to be working nearly as well as it used to.
Toronto's Citizen Lab noticed some unusual things happening in days surrounding the death of China's only Nobel Peace Prize winner (and longtime political prisoner), Liu Xiaobo.
On WeChat, we collected keywords that trigger message censorship related to Liu Xiaobo before and after his death. Before his death, messages were blocked that contained his name in combination with other words, for example those related to his medical treatment or requests to receive care abroad. However, after his death, we found that simply including his name was enough to trigger blocking of messages, in English and both simplified and traditional Chinese. In other words, WeChat issued a blanket ban on his name after his death, greatly expanding the scope of censorship.
We documented censorship of images related to Liu on WeChat after his death, and for the first time found images blocked in one-to-one chat. We also found images blocked in group chat and WeChat Moments (a feature that resembles Facebook’s Timeline where users can share updates, upload images, and short videos or articles with their friends), before and after his death.
China has tackled image censorship before, but it hasn't been able to achieve this in one-to-one chat until now. And it's being done stealthily to prevent senders or receivers from knowing their images have been blocked.
Similar to keyword-based filtering, censorship of images is only enabled for users with accounts registered to mainland China phone numbers. The filtering is also not transparent. No notice is given to a user if the picture they sent is blocked. Censorship of an image is concealed from the user who posted the censored image.
The censorship is only apparent to international users without registered Chinese phone numbers. And, like most blanket censorship efforts, it's far from perfect.
The exact mechanism that WeChat uses to determine which images to filter is unclear and in our testing sample we found unexpected results. Blocked images included screenshots of official government statements on Liu Xiaobo’s death, which we did not expect to be censored. We also found images that were not blocked that could be seen as sensitive, such as an image of book covers of “Charter 08” and a Biography of Liu Xiaobo, which are both banned in mainland China.
As Citizen Lab points out, this censorship effort is especially concerning, as it indicates the Chinese government is possibly in the business of internet-enabled retroactive amnesia. If it leaves the filtering in place long enough and censors enough websites and personal chats, the history of Liu Xiaobo will be slowly rewritten with narratives approved by the Chinese government.