Method for recording and playing back content encoded by a processing unit

摘要

The method involves deciphering two constants (C1, C2) provided by a central server for obtaining a local key (KLa) and an intermediate key (KI) respectively, through two keys (Ka) which are specific to a processing unit (STBa). A variable (R) is obtained by the processing unit. Contents with a content key (CK) obtained by deciphering the variable with the intermediate key are ciphered. The content with the content key equal to the variable is ciphered and stored in a storage memory (DDa). The content ciphered with the content key is restored by another processing unit.