It seems that every month, a new secure messaging network arrives on the scene. Signal, Wire, Ricochet, as well as encryption in commercial tools such as iMessage and WhatsApp. Which one should you use? How do they work? And do or don’t they keep the NSA out of your messages? We will discuss the cryptographic building blocks that are used in these systems and compare the types of attacks they can and can’t withstand, including attacks on both content and metadata.