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Method and apparatus for secure execution of software prior to a computer system being powered down or entering a low energy consumption mode

  • US 5,850,559 A
  • Filed: 08/07/1996
  • Issued: 12/15/1998
  • Est. Priority Date: 08/07/1996
  • Status: Expired due to Term
First Claim
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1. A method for secure execution of software prior to a computer system entering a reduced energy consumption state, the computer system having a processor incorporating system management capabilities, the computer system also having an application registrar maintained in protected system management memory and a stored table containing a modification detection value for programs contained in the application registrar, the computer system further including a power supply source, the method comprising the steps of:

  • registering a program with the application registrar;

    generating a system management interrupt in response to a request to place the computer system in a reduced energy consumption state;

    placing the computer system in system management mode as a result of said step of generating a system management mode interrupt; and

    executing a system management interrupt handler upon entry into system management mode, wherein said execution of the system management interrupt handler comprises the steps of;

    generating a current modification detection value for the program registered with the application register;

    determining if the stored table contains a secure modification detection value for the registered program or file;

    retrieving the secure modification detection value if it exists in the stored table;

    comparing the current modification detection value to the secure modification detection value if it exists in the stored table; and

    permitting execution of the registered program if the secure modification detection value exists in the stored table and the current modification detection value matches the secure modification detection value.

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