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Smart card system and operating method thereof

  • US 8,104,690 B2
  • Filed: 01/14/2009
  • Issued: 01/31/2012
  • Est. Priority Date: 01/31/2008
  • Status: Expired due to Fees
First Claim
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1. A smart card system comprising:

  • a smart card including a security logic circuit to detect an external attack; and

    a reader communicating with the smart card,wherein the security logic circuit detects the external attack by measuring an external input capacitance through an input/output pad of the smart card and comparing the external input capacitance to an input capacitance of the reader,wherein the security logic circuit comprises;

    an input/output driver providing a constant current to the input/output pad; and

    a capacitance measurer controlling the input/output driver to provide the constant current to the input/output pad for a predetermined time and, after providing the constant current to the input/output pad for the predetermined time, generating a control signal to inactivate communication between the smart card and the reader if a voltage of the input/output pad is lower than a reference voltage.

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