FIELD: information technology.
SUBSTANCE: in the method, a first key (24) is used to establish each channel key (24,27) and at least one cryptogram of data in message (33), received from a conditional access sub-system (3) over a data transmission channel is decrypted under an associated channel key. As a result of said decryption, at least one content descrambling key is obtained. At least part of the scrambled content data object (50a-50j) is descrambled by applying at least one decryption operation under a key (40,46) at least partly derivable from at least one a content descrambling key (37), and under a key, at least partly derivable from the first key (24).
EFFECT: preventing imitation of a conditional access system.
27 cl, 5 dwg
