Unit for managing audio/video data and access control method for said data

Example embodiments are directed to a digital audio/video (AV) data processing unit and a method of controlling access to the digital AV data. The processing unit of AV digital data includes a deciphering unit of the AV data, a decompression unit, an input/output interface of the processed AV data and communication device towards a security module. The deciphering and decompression units respectively include an encryption unit and a decryption unit, each having at least one personal key and a common encryption key. Deciphering the AV data using the control words and re-encrypting the deciphered AV data occurs only after a successful verification of the control word and the common key. After temporary storage, the re-encrypted AV data cannot be decrypted by the decryption unit unless the common key has been positively verified by the security module by way of a random number generated by the decryption unit.