Your Encrypted App Has a Leak. It's Called Metadata.

In 2014, General Michael Hayden — former director of both the NSA and the CIA — made a remark that should have ended the "I use an encrypted app so I'm fine" line of reasoning. "We kill people based on metadata," he said. He meant it literally: drone targeting decisions had been made on communication patterns alone, with no access to message content. Most people's threat model is considerably less dramatic. But the principle scales all the way down: metadata is a surprisingly complete record of