The Signal Messenger app is displayed on a smartphone in Hong Kong, China.
Roy Liu | Bloomberg | Getty Images
GUANGZHOU, China: The Signal encrypted messaging application has stopped working in China and is now only accessible via a virtual private network (VPN).
China blocks many foreign applications and services, including Facebook and Google. But previously, Signal had not been banned by the so-called Great Firewall.
Signs state that they are end-to-end encrypted, meaning that the company itself and any other external user can see the content of the messages between a sender and the intended recipient. This also means that the authorities cannot spy on messages.
CNBC tested Signal on three different devices and the messages did not pass, suggesting authorities have blocked it. The app was still available for download in the Apple App Store China.
The signal was not immediately available for comment when contacted by CNBC.
However, the messaging application 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.
The blockade of signals in China highlights the growing censorship of the Internet in the world’s second largest economy.
Signal downloads increased earlier this year after rival WhatsApp changed its terms of service to allow some data to be shared with its parent company Facebook.
According to Sensor Tower, the signal is relatively small in China, with up to 510,000 downloads from Apple’s App Store. But the app provided a rare way to send encrypted messages over a foreign platform without a VPN.
Still, the dominant messaging app in China remains Tencent-owned WeChat, with more than a billion users.