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Communication protocol for device authentication

  • US 8,296,565 B2
  • Filed: 03/06/2007
  • Issued: 10/23/2012
  • Est. Priority Date: 03/27/2006
  • Status: Expired due to Fees
First Claim
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1. A method for a device to authenticate an accessory having at least one communication port connected to the device, the method comprising:

  • monitoring the at least one communication port;

    detecting the accessory attached to the at least one communication port;

    driving the at least one communication port to a first voltage level to maintain the accessory in a sleep mode;

    transitioning the at least one communication port to a second voltage level to initiate a wake up condition in the accessory;

    transmitting a wake up command to the accessory via the at least one communication port;

    transmitting from the device to the accessory an authentication command via the at least one communication port, wherein the authentication command comprises a plaintext challenge to the accessory, wherein the device stores multiple challenge/response vectors before transmitting the plaintext challenge, each of the vectors being different from the other vectors and the different vectors being concurrently stored by the device, and each vector including a plaintext challenge associated with a cyphertext response, and wherein the device selects the plaintext challenge included in the authentication command from among the plaintext challenges included in the stored multiple challenge/response vectors;

    receiving an information request response via the at least one communication port from the accessory, the received information request response comprising a cyphertext response;

    comparing the received cyphertext response with the stored cyphertext response associated with the transmitted plaintext challenge;

    permitting use of the accessory when the received cyphertext response matches the stored cyphertext response associated with the transmitted plaintext challenge; and

    limiting use of the accessory when the received cyphertext response does not match the stored cyphertext response associated with the transmitted plaintext challenge;

    wherein the accessory comprises a secure authentication image file including data in an array of locations, and an accessory processor for receiving the wake up command, generating the cyphertext response using the secure authentication image file, and transmitting the cyphertext response to the device through the at least one communication port.

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