Source: South China Morning PostUsers of the secure messaging app Signal were unable to access the service in mainland China on Tuesday morning, making it the latest foreign social messaging service to fall victim to the country’s Great Firewall.The app joins the likes of Facebook, Google, Twitter and many other popular services that are inaccessible in China without the use of a virtual private network (VPN) or another circumvention tool. Existing users can no longer send messages and aspiring users cannot sign up for a new…Read More