Patent ID: 7672456

Claim:
A method of operating a group (G) of receivers and transmitters to make the same information (K c ) available to several receivers ( 1 ) belonging to the group (G) of receivers, each receiver i in the group (G) comprising a central processing unit ( 2 ) and information storage means ( 3 , 4 , 5 ), the storage means storing information (SA i ) specific to each receiver i, respectively, the method comprising: enabling each receiver to access information (b i ) before making (K c ) available; and transmitting a secret key (K) to all receivers, just before making (K c ) available; operating each receiver to calculate K c from a pre-defined relation K c =(K, b i , SA i ) where (f) is a given function, (K) is a secret key common to all the receivers, and (b i ) is information different for each receiver and for each value of the secret key (K).