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Priority claimed from EP04102667Aexternal-prioritypatent/EP1605698A1/en
Application filed by Nagracard SafiledCriticalNagracard Sa
Publication of TW200605595ApublicationCriticalpatent/TW200605595A/en
The aim of this invention is to propose a solution to prevent the modification of access conditions to an encrypted multimedia content. This aim is achieved by a method to secure an event with control words (CW), the use of this event by user units being subjected to access conditions (AC), said method comprising the following steps: - generation of a pseudo-random number (RNG), - formation of a control block (CB) by the association of the pseudo-random number (RNG) and the access conditions (AC), - calculation of the control word (CW) by the application of a unidirectional function (F) on the control block (CB), - use of the control word (CW) to encrypt the event, - transmission of the control block (CB) to the user units.
TW094106856A2004-03-112005-03-07Method to secure a broadcasted event
TW200605595A
(en)