Method and system for providing security to processors
OwnerHugo Cheung, Lu Yuan +2inventors
InventorsHugo Cheung, Lu Yuan, Terence Chiu, Bolanle O. Onodipe
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Abstract
There are various methods of securing programs and data on a processor. The external address enable pin of the processor is sampled upon a power-on or reset to the processor, to determine whether or not accesses to external memory are allowed. Other changes to the external address enable pin are thereafter ignored. In addition, if it is determined that an internal memory access is occurring, the contents of such an access can be masked to prevent unauthorized viewing of the memory contents via an external memory bus. In addition, a programmable security bit may be set to disable the dumping of flash memory contents, allowing only the erasing of the flash memory.
Claims18
A method of securing the contents of the memory in a microprocessor system comprising:
- determining, after a power-on/reset of the microprocessor, the status of an external addressing status pin;
- and
- preventing accesses to external addresses if said external addressing pin is set.
A method of securing the contents of the memory in a microprocessor system comprising:
- determining, upon a power-on/reset of the microprocessor, the status of a programmable security bit;
- and
- disabling flash memory commands in the event that the programmable security bit is set, such that a disabled flash memory command has no effect on the microprocessor system.
A method of securing the contents of the memory in a processor system comprising:
- determining whether a particular memory access requests access to external memory;
- and
- in the event that the memory access does not request access to external memory, masking the memory output ports such that the result of the memory access is not accessible through monitoring of the processor.
A processor with security features comprising:
- means for determining the status of a pin indicating the status of external memory accesses;
- and
- means for preventing accesses to external memory.
Dependencies are inferred from the claim text.