Encryption vs. Metadata: What Really Remains Private?

Messages in messengers are encrypted – and therefore secure, right? But even if no one but you and the recipients can read the content, metadata often remains: Who communicates with whom, when, and how often? These traces often reveal more than one might think – from identity and location to personal interests. The former NSA director Michael Hayden highlighted how crucial metadata can be, emphasizing that they are used to identify targets. But can such data be avoided altogether? We present methods that aim to reduce metadata – and where the limits of what is possible lie.