Matrix has become the messaging app of choice for top-secret communications

However unimpeachable Durov's credentials were, the French government did not want its messages to be hosted on the servers of a Russian company - or an American company, for that matter, which also ruled out Facebook-owned WhatsApp. "It's a rare instance of the French and the English managing to work together," says Matrix's co-founder Matthew Hodgson. Everyone can run the Matrix protocol on their own servers, and participate in conversations hosted on other servers if they so wish. In France's case, the government designed a system centred on multiple separate servers for each ministry, Hodgson says, "And yet, everybody can still talk to everybody else." The decentralised architecture - modelled after open-source software Git - reduces the repercussions of technical incidents, which remain confined to the specific affected servers, while ensuring that the conversation goes on. "There is never a single point of control or failure." Matrix's makeup has proved attractive for at least three more governments in addition to France, security services and military organisations - including the German army - and tech corporations such as Mozilla. For the Matrix Foundation, a non-profit counting Hodgson and Le Pape among its members which defines and guards the project's principles and goals, dealing with high-profile customers is a spur to hold the project to impossibly high standards. "For a typical consumer messaging app, you might be trying to protect your users from malicious governments attacking them. Here, there's scope for malicious governments attacking each other," Hodgson says.