Traitor tracing schemes help trace the source of leaks when secret or proprietary data is sold to many customers.In a traitor tracing scheme, each customer is given a different personal decryption key.(Traitor tracing schemes are often combined with conditional access systems so that, once the traitor tracing algorithm identifies a personal decryption key associated with the leak, the content distributor can revoke that personal decryption key, allowing honest customers to continue to watch pay television while the traitor and all the unauthorized users using the traitor's personal decryption key are cut off).Traitor tracing schemes are used in pay television to discourage pirate decryption -- to discourage legitimate subscribers from giving away decryption keys.