Patent ID: 7443280

Claim:
A rolling-code based process for the unambiguous identification of serial numbers in a data communication over a data communication system within a vehicle between at least first and second subscribers which have identical serial number sets stored in respective storage devices, said process comprising: generating a first challenge relative to a serial number and transmitting, on at least one data line of a bus system within the vehicle, the first challenge from the first subscriber to the second subscriber; analyzing the first challenge received from the first subscriber to determine whether the same serial number is stored at a corresponding position in the second subscriber; generating a corresponding first response and transmitting, on the at least one data line, the first response as an output from the second subscriber to the first subscriber when the same serial number is stored at said corresponding position in the second subscriber; generating a dummy response and transmitting, on the at least one data line, the dummy response as the output from the second subscriber to the first subscriber when the same serial number is not stored at said corresponding position in the second subscriber; comparing the output from the second subscriber to determine if a serial number expected as a result of the first challenge and the output from the second subscriber are identical; outputting an identification signal from the first subscriber when the expected serial number and the output are the same; and outputting no identification signal otherwise.