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Apparatus and method for managing a microprocessor providing for a secure execution mode

  • US 8,978,132 B2
  • Filed: 10/31/2008
  • Issued: 03/10/2015
  • Est. Priority Date: 05/24/2008
  • Status: Active Grant
First Claim
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1. An apparatus providing for a secure execution environment, comprising:

  • an x86-compatible microprocessor, comprising;

    one or more execution units, configured to execute non-secure application programs and a secure application program, wherein said non-secure application programs are accessed from a system memory via a system bus, and wherein said secure application program is executed in a secure execution mode;

    a cryptographic unit;

    a processor key register, coupled to said cryptographic unit, configured to store a cryptographic key that is unique to said x86-compatible microprocessor, wherein said cryptographic key is employed to encrypt said secure application program for storage, and wherein said processor key register can only be read by said cryptographic unit; and

    secure execution mode logic, configured to monitor conditions corresponding to said x86-compatible microprocessor that are associated with potential security exposure and tampering, and configured to cause said x86-compatible microprocessor to transition to a degraded operating mode from said secure execution mode following detection of a first one or more of said conditions, wherein said degraded operating mode exclusively provides for execution of BIOS instructions, said BIOS instructions comprising instructions to allow for user input and display of messages; and

    a secure non-volatile memory, coupled to said x86-compatible microprocessor via a private bus, configured to store said secure application program, wherein said secure application program is encrypted in said system memory according to an asymmetric cryptographic algorithm, and wherein, upon enablement of said secure execution mode, said microprocessor encrypts said secure application program according to a symmetric key algorithm and transfers said secure application program to said secure non-volatile memory over said private bus.

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