Patent ID: 7228439

Claim:
A method for processing an event, the method comprising the steps of: receiving an event in encrypted form at a user unit connected to a security unit, the event being encrypted by at least one control word; receiving at least one control message in encrypted form at the user unit, the control message including the at least one control word and at least one access condition for the event; decrypting the at least one control message in the security unit; calculating in the security unit a receipt for the event using a unique key, the receipt being based at least in part on information in the at least one control message; storing the event in encrypted form, the at least one control message in encrypted form, and the receipt in a storage unit connected to the user unit; prior to accessing the encrypted event stored in the storage unit, retrieving the receipt and the at least one control message from the storage unit to the security unit; calculating a signature using the unique key based on the same information in the at least one control message used to calculate the receipt; comparing the calculated signature to the receipt; and if the calculated signature matches the receipt, allowing access to the event without regard to rights stored in the security module.