Power-on password functions for computer system
First Claim
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1. A method of operating a computer system, comprising the steps of:
- (a) storing a password and a pair of representations of said password in a non-volatile memory accessible by a CPU of said system;
(b) upon power-on initialization of said system, accessing said non-volatile memory to check said password against one of said pair of representations, and, if a match is not found, to check said password against the other of said pair;
(c) if a match is found in either of said checks, then writing the good one of the pair to the other or said pair, and comparing with said stored password a password entered by a user from a keyboard of said computer system, and if the passwords are the same, allowing normal operation of said system by said user to proceed, but, if the passwords do not agree, locking said user out of the system;
(d) if a match is not found in either one of said checks, then zeroing said stored password and said representations and allowing normal operation of the system to proceed without entry of a password by the user.
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Abstract
A power-on password security function for a digital computer system allows the system software to distinguish between authorized and unauthorized users. Safeguards are made against corruption of password data which could lead to lock-out authorized users, and redundant checks allow the security function to operate even when first-level checks fail. The battery-powered RAM storage area used to hold the password when the system is turned "off" is protected against being accessible by unauthorized users when the system is turned "on".
126 Citations
20 Claims
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1. A method of operating a computer system, comprising the steps of:
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(a) storing a password and a pair of representations of said password in a non-volatile memory accessible by a CPU of said system; (b) upon power-on initialization of said system, accessing said non-volatile memory to check said password against one of said pair of representations, and, if a match is not found, to check said password against the other of said pair; (c) if a match is found in either of said checks, then writing the good one of the pair to the other or said pair, and comparing with said stored password a password entered by a user from a keyboard of said computer system, and if the passwords are the same, allowing normal operation of said system by said user to proceed, but, if the passwords do not agree, locking said user out of the system; (d) if a match is not found in either one of said checks, then zeroing said stored password and said representations and allowing normal operation of the system to proceed without entry of a password by the user. - View Dependent Claims (2, 3, 4, 5)
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6. A metnod of operating a computer system, comprising the steps of:
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(a) storing a data value and at least one representation of said data value in a non-volatile memory accessible by a CPU of said system; (b) upon power-on initialization of said system, accessing said non-volatile memory to check said data value against said at least one representation, and, if a match is not found, to again check said data value against said at least one representation; (c) if a match is found in either of said checks, then entering a first type of operation of said computer system including comparing a new data value accessed by said computer system to said stored data value; (d) if a match is not found in either one of said checks, then entering a second type of operation of the system. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
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14. A computer having a power-on password function for restricting access, comprising:
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(a) a CPU executing instructions fetched from a memory address space to perform operations on data stored in said memory address space, the CPU also having an I/O address space; (b) a restricted-access data storage area accessible by the CPU in said I/O address space, said restricted-access area being writable by said CPU, said restricted-access area storing password data used with said power-on password function and storing at least one representation of said password data for checking against said password data upon power-on initialization of the computer; (c) and means for locking out said CPU from access to said data storage area after said power-on initialization by writing to a selected location of said I/O address space. - View Dependent Claims (15, 16, 17, 18)
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19. A computer having a power-on function for initialization, comprising:
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(a) a CPU executing instructions fetched from a memory address space to perform operations on data stored in said memory address space, the CPU also having an I/O address space; (b) a restricted-access data storage area accessible by the CPU in said I/O address space, said restricted-access area being writable by said CPU, said restricted-access area storing data used upon power-on initialization of the computer; (c) and means for locking out said CPU from access to said data storage area after said power-on initialization by writing to a selected location of said I/O address space. - View Dependent Claims (20)
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Specification