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Use of global clock to secure and synchronize messages in XM and SMS messages to a vehicle

  • US 7,805,612 B2
  • Filed: 12/02/2005
  • Issued: 09/28/2010
  • Est. Priority Date: 12/02/2005
  • Status: Active Grant
First Claim
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1. A method for providing security for a communications signal transmitted from a server to a vehicle, said method comprising:

  • periodically receiving a global time signal by the vehicle and the server;

    synchronizing a local time signal in the vehicle and the server to the global time signal;

    adding a server local time signal to a one-way message including a vehicle identification number and a function code in the server;

    encrypting the message in the server;

    transmitting the message from the server to the vehicle;

    receiving the message in the vehicle;

    decrypting the message in the vehicle;

    comparing a vehicle identification number of the vehicle with the vehicle identification number in the message;

    comparing the server local time signal in the message with a vehicle local time signal in the vehicle; and

    performing a function associated with the function code if the vehicle identification numbers match and the server local time signal in the message is within a predefined window of the vehicle local time signal.

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