China’s internet censors have demonstrated a new capability to delete images in one-on-one chats as they are being transmitted, making them disappear before receivers see them. The new image-filtering capability kicked into high gear last week as Chinese dissident Liu Xiaobo lay dying from liver cancer and politically minded Chinese tried to pay tribute to him, according to activists and a new research report.
A close friend of the long-jailed Nobel Peace Prize laureate, Wu Yangwei, said he used popular messaging app WeChat to send friends a photo of a haggard Mr. Liu embracing his wife. Mr. Wu believed the transmissions were successful, but he said his friends never saw them.
Mr. Wu revealed that sometimes you can get around censors by rotating the photo although the technique doesn’t always work. The Chinese internet censorship first concentrated on the development of word-screening software to root out politically objectionable content.
There have been reports from users of WhatsApp in China and security researchers on the widespread service disruptions amid fears that the popular messaging service may be at least partially blocked by authorities in the world's most populous country.
The WhatsApp users in China reported Tuesday on other social media platforms that the app was partly inaccessible unless virtual private network software was used to circumvent China's censorship apparatus, known colloquially as The Great Firewall.
WhatsApp offers end-to-end encryption, it has a relatively small but loyal following among users seeking a greater degree of privacy from government snooping than afforded by popular domestic app WeChat, which is ubiquitous but closely monitored and filtered.
The Chinese government is in the midst of preparation for a sensitive party congress while Chinese censors this week revved up a sprawling effort to scrub all mention of Liu Xiaobo, the Nobel Peace Prize laureate who died Thursday in government custody.
The University of Toronto’s Citizen Lab released a report detailing how Chinese censors have the capability to intercept, in real time, images commemorating Liu in private one-on-one chats on WeChat, a feat that hinted at the government's image recognition capabilities.
There are claims pointing out that pictures were also the focus of the move to censor WhatsApp. On late Tuesday, users in China could send texts over WhatsApp without the use of VPNs, but not images.
One of the renowned cryptography researcher, Nadim Kobeissi, who is based in Paris who has been investigating the WhatsApp disruption, said that he believed The Great Firewall was only blocking access to WhatsApp servers that route media between users while leaving servers that handle text messages untouched. He said voice messages also appeared to be blocked. However, Kobeissi revealed that there was no evidence to suggest that Chinese authorities were decrypting WhatsApp messages.
One of the Chinese censorship researcher known by his pseudonym Charlie Smith said authorities appeared to be blocking non-text WhatsApp messages wholesale precisely because they have not been able to selectively block content on the platform like they have with WeChat, which is produced by Shenzhen-based internet giant Tencent and legally bound to cooperate with Chinese security agencies.
Smith also highlighted that since WhatsApp content is encrypted, the Chinese government has moved to brute censor all non-text content.