A conditional access system is provided wherein digitized data are received in successive data packets at least some of which are scrambled. The digitized data contain content data and access control data. The system has a module with descrambler circuitry and a security device such as a smart card adapted...http://www.google.fr/patents/US7400728?utm_source=gb-gplus-shareBrevet US7400728 - Conditional access system and copy protection
