TAIPEI – Messages app Signal became unusable for many people in mainland China this week, choking one of the last widely used messaging apps that could send and receive encrypted messages in the country without a virtual private network.
The government’s apparent attempt to block Signal strengthens its grip on public and private discourse in China, where many social media and messaging apps, including Facebook
Twitter and, most recently, the popular social audio platform Clubhouse, have been banned.
Signal users in mainland China started reporting problems sending and receiving messages in the app around Monday evening. Using a virtual private network, or VPN, a tool that allows internet users to bypass China’s extensive web filtering system, resolved these issues, leading users to conclude that the app was blocked in China.
Some also reported registration issues, another common censorship practice that hit Clubhouse last month, where users are unable to sign in with their phone number because the verification text code is never received.
The issues started on Sunday and included discontinued registration and network blockages, a person familiar with the matter said. China’s Cyberspace Administration, the country’s internet regulator, did not immediately respond to a request for comment.
On Tuesday, the Chinese Ministry of Foreign Affairs referred a question about the apparent ban to the relevant department, but said the Internet is open in China and that the government operates the Internet in accordance with the law.
Signal uses end-to-end encryption, which prevents third parties from accessing communications between the sender and receiver. It includes features such as disappearing messages and media, and is promoted as a tool for secure and private communication. Similar encrypted messaging apps, such as Telegram and WhatsApp from Facebook Inc., are also not accessible in China without a VPN.
Signal surged in popularity among Chinese users last year after the US government said it would ban WeChat
China’s most popular messaging app, operated by Tencent Holdings Ltd. Downloads had also surged in Hong Kong after lawmakers passed national security legislation and suppressed pro-democracy protests.
WeChat uses client-to-server encryption, giving Tencent full access to data between senders and recipients. The app is ubiquitous in China and largely a necessity for everyday life through its messaging and payment services. It is also known for its censorship on sensitive matters, such as political criticism or during the coronavirus outbreak in Wuhan.
In February, Chinese censorship blocked Clubhouse after the app began to gain traction in the country, sparking discussions on sensitive topics that were generally limited in China, such as the treatment of Uyghur Muslims in China or the Tiananmen Square protests.
“It has always been a surprise that Signal lasts just as long as the purpose of the app is to enable encrypted communication.”
As with Clubhouse, some saw the loss of Signal as inevitable due to China’s extensive censorship machinery and tightening controls over its internet users.
“It’s always been a surprise that Signal lasts just as long as the purpose of the app is to enable encrypted communication,” said James Griffiths, author of “The Great Firewall of China: How to Build and Control an Alternative Version from the Internet. “
Yaqiu Wang, China researcher at Human Rights Watch in New York, said Signal was the last encrypted messaging app she could easily use to securely connect with friends and activists in mainland China.
While Signal can still work with a VPN, these have become more difficult to access in China in recent years after China tightened rules for the tool. At least hundreds of VPNs have been removed from app stores, while VPN users and providers have been fined.
“These are all indications that it will become increasingly difficult for people to safely talk to people about sensitive issues,” said Ms. Wang. “I’m really concerned about communication for people in China.”
While there was no apparent catalyst for the apparent ban, some experts speculated that Signal’s recent popularity with mainland users may have contributed.
According to research firm Sensor Tower, downloads of Signal on iOS, Apple’s operating system, gained momentum in China over the past year, before stopping in February and March. Signal installs hit a monthly high of 52,000 in August after the US WeChat ban was announced and rose again in January, with around 49,000 installs.
Still, Signal users in China are a fraction of those on WhatsApp or Telegram, according to data from Sensor Tower. Signal downloads on iOS have reached a total of about 510,000 in China, compared to 9.6 million WhatsApp installations and three million Telegram installations.
Signal was also blocked in Iran in January. The company has said it has launched a fix for that network blocking and was exploring more ways to get around the ban.
Write to Stephanie Yang at [email protected]
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