Method and structure for securing access to a computer system

• US 5,475,839 A
• Filed: 11/16/1994
• Issued: 12/12/1995
• Est. Priority Date: 03/28/1990
• Status: Expired due to Fees

• Current Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Lee, R. Jeff, Watson, Bruce W.
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): Wang, Peter Y.
• Application Number:
  US08/341,302
• Time in Patent Office: 391 Days
• Field of Search: 395/650, 395/700, 395/425, 395/325, 395/575, 380/4, 235/380
• US Class Current: 713/2
• CPC Class Codes: G06F 11/08 Error detection or correction by redundancy in data representation, e.g. by using checking codes
• CPC Class Codes: G06F 11/1417 Boot up procedures
• CPC Class Codes: G06F 21/565 by checking file integrity
• CPC Class Codes: G06F 21/575 Secure boot

Abstract

Tests are performed prior to or during the boot operation to determine whether files are corrupted. This may indicate the presence of a virus. If a potential error is detected, boot is halted, allowing the user to boot from uncorrupted files. In another embodiment, an uniquely formatted floppy diskette is used as an access diskette serves as a hardware key to gain access. In another embodiment, a host controls information stored locally. In another embodiment, security from unauthorized access is provided once a valid user has legitimately accessed a computer. In response to a predefined hot key or a predetermined period of time during which the user has not provided input, portions of the computer are disabled. Upon entry of access information by the valid user, the disabled features are enabled. In another embodiment, access to the computer is made more difficult in response to invalid access attempts. In one embodiment, once a threshold number of invalid access attempts is reached, the computer is locked up, requiring reboot, thereby increasing the difficulty of a would be intruder to gain access to the computer. In one embodiment, once the threshold value is reached, it is reset to a lower value.

Claims

1. A method for controlling access to computer system during a boot operation comprising the steps of:

receiving user authorization information from a prospective user;

determining if said user authorization information is valid;

if said user authorization information is valid, allowing said prospective user to have access to said computer system by booting said computer system; and

if said user authorization information is invalid, increasing the difficulty of gaining access to said computer system by reducing threshold number to a lower threshold number following a number of invalid user authorization attempts which equals or exceeds said threshold number.

2. A method as in claim 1 wherein said step of determining if said user authorization is valid further comprising the step of remote polling by a remote host computer.

3. A method as in claim 1 which further comprises the step of allowing the user to disable said computer during usage, requiring receipt of user information for further access to said computer.

4. A method as in claim 6 wherein said user authorization information is a password which differs from a password used to gain access to said computer system prior to said inactivation.

5. A method as in claim 1 wherein upon said prospective user gaining access to said computer, information pertaining to the number of unsuccessful attempts to access said computer are displayed to the user.

6. A method as in claim 1 wherein said computer system is automatically inactivated after a predetermined period of inactivity.

7. A method as in claim 6 wherein during said period of inactivation, said computer continues processing activity.

8. A method as in claim 6 wherein during said period of inactivation input/output functions resulting from said computer processing are disabled.