Cryptography – Key management – Having particular key generator
Patent
1993-08-12
1994-09-20
Swann, Tod R.
Cryptography
Key management
Having particular key generator
380 20, H04M 7167
Patent
active
053496418
ABSTRACT:
A process for the transmission and reception of scrambled conditional access programs, which are synchronously transmitted with entitlement control messages (ECM), with a reduced program switching time. The entitlement control messages (ECM) have check words, which are changed after a period of time called a phase, for descrambling the conditional access programs. The process includes transmitting main check messages (ECMp) for a main access program at a first frequency (Fp) and transmitting secondary check messages (ECMs) for secondary programs at a lower, second frequency (Fs). The secondary check messages (ECMs) are transmitted between two successive transmission of the main check messages (ECMp) such that all of the secondary check messages (ECMs) for each of the secondary programs are transmitted in a single phase. Therefore, a check word for any program is quickly acquired and program switching time is reduced.
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Union Europeenne De Radiodiffusion, Oct. 1986, pp. 213-243, G. T. Waters, "Specifications Des Systemes De La Famille MAC/Packets".
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Coutrot Francoise
Giachetti Jean-Luc
France Telecom Establissement Autonome de Droit Public
Swann Tod R.
Telediffusion de France
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