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Method and apparatus for certifying services obtained using a portable carrier such as a memory card

  • US 4,825,052 A
  • Filed: 12/30/1986
  • Issued: 04/25/1989
  • Est. Priority Date: 12/31/1985
  • Status: Expired due to Term
First Claim
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1. A method of certifying a service furnished with the aid of a portable card which is coupled to an apparatus, the card having a memory (M2) and processing circuits (T2), the method comprising calculating in the processing circuits of the card a first result (R) based upon an internal parameter (PI) prerecorded in the memory of the card and/or upon an external parameter (PE) and upon a secret key (S);

  • preparing a certificate (C) comprising at least first and second data, the first datum being the first result (R) calculated by the processing circuits (T2) and the second datum being the internal and/or external parameters (PI, PE) used for calculating the result (R);

    recording the certificate (C) on a carrier (3) as proof that the service was furnished;

    recalculating in second processing circuit (T2) a second result (R) based upon the second datum recorded on the certificate and upon another secret key (S) corresponding to the first-mentioned secret key, comparing the second result with the first result recorded on the certificate, and certifying, upon the first and second results matching, that the service was properly obtained with the portable card.

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