| 摘要 |
The invention concerns a method for data transmission between a transmitting station (100e) and a plurality of receiving stations (100r) which consists in transmitting from the transmitting station to the receiving stations data encrypted with a first key, and at least a control message transporting a second key. The invention is characterised in that the first key, used for decrypting, is recovered in each receiving station from the second key and from at least a data selected among the set of data available in the receiving stations, based on a selection command periodically transmitted between the transmitting station and the receiving station. The invention is applicable to pay television. FIG. 2: 104e, 114e, 116e, 122e, 124e ENCRYPTION UNITS 104r, 114r, 116r, 122r, 124r DECRYPTION UNITS A ENCODING KEY B ENTITLEMENT CONTROL MESSAGE C ENTITLEMENT MANAGEMENT MESSAGE D OPERATING KEY E CLIENT KEY S COMMAND MESSAGE
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