ToTok, an Emirati messaging app that has been downloaded to millions of phones, is the latest escalation of a digital arms race. IMAGE: The Aldar Building in Abu Dhabi, United Arab Emirates, where the Emirates’ signals intelligence agency and Pax AI, a data mining firm linked to ToTok, have their offices. Photo Credit...Ben Job/ReutersWASHINGTON — It is billed as an easy and secure way to chat by video or text message with friends and family, even in a country that has restricted popular messaging services like WhatsApp and Skype.But the service, ToTok, is actually a spying tool, according to American officials...