| 摘要 |
The invention relates to a method and an access control system for controlling access to content, said content being encrypted by content keys (F 1, F 2 ) stored in a key-locker ( 5 ) encrypted by a key-locker key (KLK). In order to restore the security of the access control system by updating a PC application or a computer ( 2 ) running the PC application without the need for updating a device ( 3 ) using said content, a method is proposed comprising the steps of:-defining at least two access keys (K 1, K 2 ) and one string (x) by a cryptographic unit ( 1 ),-encrypting said string (x) by said cryptographic unit ( 1 ) using said access keys (K 1, K 2 ) obtaining at least two cryptographic values (h, E),-storing said cryptographic values (h, E) on a computer ( 2 ) adapted for accessing said content, enabling said computer ( 2 ) to calculate said key-locker key (KLK),-storing said access keys (K 1, K 2 ) on a device ( 3 ) adapted for accessing said content and transmitting at least one of said cryptographic values (E) either from said computer ( 2 ) or from said cryptographic unit ( 1 ) to said device ( 3 ), enabling said device ( 3 ) to calculate said key-locker key (KLK).
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