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Security device for a semiconductor chip

  • US 5,881,155 A
  • Filed: 03/31/1997
  • Issued: 03/09/1999
  • Est. Priority Date: 04/01/1996
  • Status: Expired due to Term
First Claim
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1. Security device for preventing access to confidential information stored in a semiconductor chip ("protected chip"), comprising:

  • a second semiconductor chip ("protective chip"), said protected and protective chips facing each other and being coupled to each other by communication terminals, the protected chip being coupled to external circuits via said protective chip, and wherein said chips have therebetween a semiconductor resin having a nonhomogeneous electrical resistivity, said protective chip including means for measuring a plurality of resistances through the semiconductor resin, and means for determining, at least from the measured resistances, an encryption key communicated to the protected chip, which key protect the confidential information.

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