Keeping cyber attackers and eavesdroppers out of electronic assets is a tricky business. Unpredictable random numbers are at the heart of all modern computer security today. The Entropy Engine is a computer hardware system that uses quantum mechanics to generate an inexhaustible supply of pure random numbers at speeds of 200 megabits per second. The unpredictability and speed of such entropy provides the highest possible level of defense because the quantum processes used in this technology are irreducibly random. Modern cryptosystems rely on high-quality randomness, consuming surprisingly high quantities of random numbers to generate their keys and perform cryptographic operations. Unlike all these systems, the Entropy Engine uses the unique properties of quantum mechanics to generate true entropy in a way that makes it immune from all external influences.