Using Device Linking to Eavesdrop on WhatsApp and Signal

Modern messaging apps allow users to link their phone accounts to their computer desktop. Eavesdroppers are taking advantage of this capability: Apps such as WhatsApp Web and Signal Desktop allow people to use their accounts on other devices, such as laptops or desktop computers. Germany’s Customs Office has been using these features to connect a police-controlled computer to a suspect’s account. Once connected, messages can be delivered to that computer without the police having to crack the en...