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Apparatus for validating the presence of an authorized accessory

  • US 7,454,617 B2
  • Filed: 02/19/2004
  • Issued: 11/18/2008
  • Est. Priority Date: 07/15/1997
  • Status: Expired due to Fees
First Claim
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1. An apparatus for validating the presence of an authorized consumable unit of a printing device, the consumable unit having a first authentication integrated circuit that is configured to store a secret key KA and data on a printing consumable of the consumable unit, the apparatus comprising:

  • a second integrated circuit which stores a public key KT and is configured to hold a random number function which returns random number R, the second integrated circuit being configured to apply a function F[R] to return FKT[R], based on the public key KT, and the first integrated circuit being configured to apply a function D[FKT[R]] to return DKA[FKT[R]], based on the secret key KA; and

    a control system which is configured to request FKT[R] from the second integrated circuit, to request DKA[FKT[R]] from the first integrated circuit to obtain RA, and to compare R return by the second integrated circuit with RA returned by the first integrated circuit.

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