The most prolific, comprehensive, and intrusive mass surveillance device ever designed by man is the cellular phone you carry with you everywhere you go. This device tracks and collects a staggering amount of personal information. That valuable data is sold and stored indefinitely by a an equally staggering number of companies, government entities, and data brokers that you never knew even existed. How is this data being used, and how will it be used in the future? Communicating with loved ones, colleagues, and other people is a fundamental human necessity. In today's digital world, the ways in which we communicate are convenient, instant, and often happen without even thinking about the technology that makes it all possible. The privacy of our communications, our movements, and our thoughts are also a cornerstone of a free and open society. COMSEC uncovers the methods used by businesses, data brokers, and governments to harvest our data using the surveillance device that we allow into our lives in order to stay constantly connected. The authors share detailed first-hand knowledge about the tools, tradecraft, and techniques used to mitigate and eliminate the threats posed by tracking our communications. These same tactics, taught to covert law enforcement officers, military operatives, and the clandestine community, are explained here for anyone to adopt for their own personal communication strategy. COMSEC is a must read if private and secure communications is important to you. Choose the tactics appropriate for your threat model, or choose to take more extreme measures. If you are a government employee, service member deployed behind enemy lines, a journalist, activist, dissident, politician, shady character of any type, or a privacy advocate, COMSEC offers the tried and tested solutions that you need to know.