Bios based method to disable and re-enable computers

• US 6,618,810 B1
• Filed: 05/27/1999
• Issued: 09/09/2003
• Est. Priority Date: 05/27/1999
• Status: Expired due to Term

• Current Assignee: Dell USA LP (Dell Technologies Inc.)
• Original Assignee: Dell USA LP (Dell Technologies Inc.)
• Inventors: Dirie, Herzi
• Primary Examiner(s): HUA, LY
• Application Number:
  US09/320,565
• Time in Patent Office: 1,566 Days
• Field of Search: 713/200, 713/201, 713/181, 713/172, 713/169, 713/185, 235/382, 235/382.5, 235/487, 705/405, 380/211, 380/251
• US Class Current: 726/27
• CPC Class Codes: G06F 21/575 Secure boot
• CPC Class Codes: G06F 21/71 to assure secure computing or processing of information

Abstract

A system, method, and program product for disabling operation of a computer system upon expiration of an authorized period of time, and to re-enable operation of the computer system when an extension of time is authorized by the provider of the system. Security features including protected memory for a security timer that keeps track of the amount of time the computer system has been utilized, and encrypted messages for authorizing extensions of time are employed. At one or more predetermined times before the security timer expires, an expiration notice is published to remind the user to renew before the computer system is disabled. After the security timer expires and the computer system is disabled, the computer system may be re-enabled by entering an update to the security timer. Providers of computer systems may thereby prohibit use of the computer systems once the authorized amount of time has expired, and thus encourage payment of lease fees or other agreed performance.

Claims

1. A method for disabling operation of a computer system, the computer system including a data processor, a read only memory, a clock, a security timer operative with the clock, and a BIOS operative with the security timer, the method comprising:

storing a first portion of the BIOS in the read only memory, the first portion of the BIOS including program instructions for initializing the system;

updating the security timer with information from the clock;

determining whether the security timer has expired; and

disabling the computer system when the security timer has expired by invoking disabling instructions in the first portion of the BIOS so that the computer is not initialized.

2. The method, as set forth in claim 1, wherein the computer system further includes a clock, and updating the security timer includes:

reading the clock;

determining the amount of time since the clock was last read; and

updating the security timer based on the amount of time since the clock was last read.

3. The method, as set forth in claim 2, further comprising determining the validity of the clock reading and disabling the computer system when the clock has been tampered.

4. The method, as set forth in claim 1, wherein updating the security timer includes decrementing the security timer at a fixed time interval.

5. The method, as set forth in claim 1, further comprising:

publishing a notice that the amount of time authorized for using the computer system has expired.

6. The method, as set forth in claim 1, further including:

determining when to increment the security timer by an authorized extension of time.

7. The method, as set forth in claim 1, further comprising:

re-enabling the computer system by incrementing the security timer when an extension of time is authorized; and

initializing the computer system for operation.

8. The method, as set forth in claim 7, wherein re-enabling the computer system by incrementing the security timer when an extension of time is authorized includes utilizing a cryptographic message system for determining the validity of an extension of time.

9. The method, as set forth in claim 1, further comprising publishing a notice when the security timer has a predetermined amount of time remaining.

10. A security system for enabling and disabling initialization of a computer system, the computer system including a central processing unit, a memory, and program instructions for initializing and controlling operation of the computer system, the security system comprising:

a security timer for measuring the amount of time the computer system has been utilized;

a first set of program instructions for comparing an amount of time authorized for utilizing the computer system to the amount of time the computer system has been utilized; and

a second set of program instructions for at least partially halting initialization of the computer system when the amount of time the computer system has been utilized exceeds the amount of time authorized for utilizing the computer system.

11. The security system, as set forth in claim 10, further comprising:

a third set of program instructions for re-enabling operation of the computer system when an authorized extension of time for utilizing the computer system is detected.

12. The security system, as set forth in claim 10, wherein the security timer resides in write protected memory.

13. The security system, as set forth in claim 10, further comprising:

a data encryption and decryption system for receiving and authenticating updates to the security timer.

14. The security system, as set forth in claim 10, further comprising:

a third set of program instructions for publishing a notice at a predetermined time before the security timer expires.

15. The security system, as set forth in claim 10, further comprising:

a third set of program instructions for determining whether the security timer reading is valid.

16. The security system, as set forth in claim 10, further comprising:

a third set of program instructions for generating a system interrupt at fixed time intervals and decrementing the time remaining on the security timer by the fixed time interval.

17. The security system, as set forth in claim 10, further comprising:

a system clock; and

a third set of program instructions for comparing the expiration time for authorized use of the computer system on the security timer to the current time of the system clock.

18. The security system, as set forth in claim 17, further comprising:

a fourth set of program instructions for checking the validity of the time on the security timer and the system clock; and

a fifth set of program instructions for at least partially disabling the computer system when the time on the security timer or the system clock is invalid.

19. A computer program product for enabling and disabling initialization of a computer system comprising:

a first set of program instructions for measuring the amount of time the computer system has been utilized;

a second set of program instructions for comparing an amount of time authorized for utilizing the computer system to the amount of time the computer system has been utilized; and

a third set of program instructions for at least partially halting initialization of the computer system when the amount of time the computer system has been utilized exceeds the amount of time authorized for utilizing the computer system.

20. The computer program product, as set forth in claim 19, further comprising:

a fourth set of program instructions for re-enabling operation of the computer system when an authorized extension of time for utilizing the computer system is detected.

21. The computer program product, as set forth in claim 20, further comprising:

a fifth set of program instructions for encrypting and decrypting updates to the security timer.

22. The computer program product, as set forth in claim 21, further comprising:

a sixth set of program instructions for publishing a notice at a predetermined time before the security timer expires.

23. The computer program product, as set forth in claim 22, further comprising:

a seventh set of program instructions for determining whether the security timer reading is valid.

24. The computer program product, as set forth in claim 23, further comprising:

an eighth set of program instructions for generating a system interrupt at a fixed time interval and decrementing the time remaining on the security timer by the fixed time interval.

25. The computer program product, as set forth in claim 24, further comprising:

a ninth set of program instructions for checking the validity of the time on the security timer; and

a tenth set of program instructions for at least partially disabling the computer system when the time on the security timer is invalid.