Modern commerce is increasingly conducted online, allowing vendors to offer a wide variety of goods and services around the clock and from any location. Today, hundreds of millions of users are registered with dozens of diverse online services.This has created highly attractive targets for cybercriminals, and massive data breaches have become more and more frequent. Every data breach, regardless of its source, allows cybercriminals to refine current data, correlate it with new data, and create profiles that can identify millions of user—with severe consequences for their victims. Data that has been lost cannot be taken back—information such as social security numbers or dates of birth cannot be revoked once leaked.