5.
    发明专利
    未知

    公开(公告)号:DE3782328T2

    公开(公告)日:1993-04-22

    申请号:DE3782328

    申请日:1987-12-18

    Applicant: IBM

    Abstract: A smart card (10) which has a instruction processor (12) which is connected to a changeable memory (16) in which application programs are stored. The card is manufactured partially blank, or without an application program stored thereon, and an application program is then loaded into the changeable memory, i.e., by downloading it from a mainframe computer. In this manner, the application program in a smart card may be changes by an authorized party. Further, a flag (22) indicates whether a program has been loaded on a smart card. Also disclosed is a method of securing the program from tampering by unauthorized parties where, in response to certain instructions (such as a dump of the application program), key portions are erased prior to execution. Application programs are loaded onto the card through the use of a double timed reset, the first of which writes a predetermined sequence on the card for a set time interval. The second reset before the end of the set time interval then indicates that a program load function is to occur and causes key selected portions of the memory to be overwritten and erased to protect key data from the previous program from being maintained or used later.

    6.
    发明专利
    未知

    公开(公告)号:DE3782328D1

    公开(公告)日:1992-11-26

    申请号:DE3782328

    申请日:1987-12-18

    Applicant: IBM

    Abstract: A smart card (10) which has a instruction processor (12) which is connected to a changeable memory (16) in which application programs are stored. The card is manufactured partially blank, or without an application program stored thereon, and an application program is then loaded into the changeable memory, i.e., by downloading it from a mainframe computer. In this manner, the application program in a smart card may be changes by an authorized party. Further, a flag (22) indicates whether a program has been loaded on a smart card. Also disclosed is a method of securing the program from tampering by unauthorized parties where, in response to certain instructions (such as a dump of the application program), key portions are erased prior to execution. Application programs are loaded onto the card through the use of a double timed reset, the first of which writes a predetermined sequence on the card for a set time interval. The second reset before the end of the set time interval then indicates that a program load function is to occur and causes key selected portions of the memory to be overwritten and erased to protect key data from the previous program from being maintained or used later.

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