Patent ID: 7010686
Filing Date: 2006-03-07
Classification: G01C,G06F,Y10S

Abstract:
1. A method for enabling access to a file, which is stored on a storage medium together with at least one other file by a computer system comprising the steps of: transmitting a device identification number ID(i-1) for the computer system, to a central station; calculating a new device identification number ID(i) using the transmitted device identification number ID(i-1) and an alternating code c in the central station; generating a first scrambled code PIN using the calculated device identification number ID(i) and a key k in the central station; generating a second scrambled code ACW using an identifier for the file which is to be enabled and the key k in the central station, transmitting the first scrambled code PIN and the second scrambled code ACW from the central station to the computer system; calculating the new device identification number ID(i) in the computer system from the previously stored device identification number ID(i-1) and the alternating code c, which is stored in a nonvolatile memory of the computer system; calculating the key k using the first scrambled code PIN and the device identification number ID(i); calculating an identifier AC for the file using the second scrambled code ACW and the key k; enabling the file provided with the identifier AC for use by the computer system.