The Signal Messenger app is displayed on a smartphone in Hong Kong, China.
Roy Liu | Bloomberg | Getty Images
GUANGZHOU, China — Encrypted messaging app Signal has stopped working in China and is now only accessible via a virtual private network (VPN).
China blocks many foreign apps and services including those from Facebook and Google. But Signal had previously not been barred by the so-called Great Firewall.
Signal claims to be end-to-end encrypted, meaning the company itself nor any outsiders can view the contents of messages between a sender and the intended recipient. This also means authorities cannot snoop on messages.
CNBC tested Signal on three different devices and messages did not go through, suggesting it has been blocked by authorities. The app was still available for download via Apple’s China App Store.
Signal was not immediately available for comment when contacted by CNBC.
The messaging app, however, still worked when used with a VPN. A VPN or virtual private network allows users to protect privacy and circumvent internet restrictions by connecting to servers around the world.
Signal being blocked in China highlights the increasing internet censorship in the world’s second-largest economy.
Downloads of Signal surged earlier in the year after rival WhatsApp changed its terms of service to allow the sharing of some data with its parent company Facebook.
Signal is relatively small in China with 510,000 downloads to date from Apple’s App Store, according to Sensor Tower. But the app provided a rare avenue for sending encrypted messages through a foreign platform without a VPN.
Still, the dominant messaging app in China remains Tencent-owned WeChat with over a billion users.
