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Data security apparatus and method

  • US 5,668,945 A
  • Filed: 02/23/1995
  • Issued: 09/16/1997
  • Est. Priority Date: 02/28/1994
  • Status: Expired due to Term
First Claim
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1. A data security apparatus for controlling whether program data stored in a replaceable, external storage medium is to be processed by a data processor, the data security apparatus comprising:

  • a security check means for detecting the presence or absence of a security code stored in an external storage medium;

    an internal storage means for storing an identification code read out from the external storage medium;

    a replacement detect means for detecting a replacement of the external storage medium with a second external storage medium;

    a judgment means for comparing the identification code stored in the internal storage means with an identification code read out from the second external storage medium and judging whether the codes correspond;

    a control means for controlling whether the program data stored in the external storage medium or the second external storage device is to be processed by the data processor or not;

    wherein, when the presence of the security code in the external storage medium is detected by the security check means, and the replacement means detects a replacement of the external storage medium with the second external storage medium, and the judgment means judges that the identification code stored in the internal storage means and the identification code read out of the second external storage medium correspond, then the security check means does not check the second external storage medium for the security code and the control means permits the program data stored on the second external storage medium to be processed by the data processor,and when the absence of the security code in the external storage medium is detected by the security check means, and the replacement means detects a replacement of the external storage medium with the second external storage medium, the security check means checks the second external storage medium for the security code,and when the external storage medium has a security code but does not have an identification code, and the replacement means detects a replacement of the external storage medium with the second external storage medium, the security check means checks the second external storage medium for the security code,and when the presence of the security code in the external storage medium is detected by the security check means, and the replacement means does not detect a replacement of the external storage medium with the second external storage medium, then the control means permits any program data stored on the external storage medium to be processed by the data processor.

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