Protecting access to microcontroller memory blocks
First Claim
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1. In a microcontroller, a method of accessing a block of memory, comprising:
- in response to an access request to the block of memory, ascertaining a security rule associated with the block of memory;
applying the security rule according to a security algorithm to determine if the access request is authorized; and
denying the access request in the event the access request is unauthorized, wherein the security rule comprises one of a plurality of security levels assigned to the block of memory, the security levels corresponding to ability of the processor to read or write to the block of memory.
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Abstract
A microcontroller provides protection to memory blocks in an embedded memory. A set of rules such as security levels mapped to memory blocks are stored in a nonvolatile supervisory memory. An algorithm for application of the rules is stored in a supervisory ROM. When a read or write operation is to be carried out, the rules are applied according to the algorithm in order to authorize or reject the read or write operation. Security levels can be modified, but only according to defined rules. In one embodiment, the security levels can only be increased.
93 Citations
15 Claims
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1. In a microcontroller, a method of accessing a block of memory, comprising:
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in response to an access request to the block of memory, ascertaining a security rule associated with the block of memory; applying the security rule according to a security algorithm to determine if the access request is authorized; and denying the access request in the event the access request is unauthorized, wherein the security rule comprises one of a plurality of security levels assigned to the block of memory, the security levels corresponding to ability of the processor to read or write to the block of memory. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. In a microcontroller having an internal processor, a method of accessing memory, comprising:
mapping a security level to each block of a plurality of memory blocks and storing the mapping in a table;
in response to an access request to a specified block of memory, determining the security level for the specified block of memory;
applying the a security algorithm using the security level to determine if the access request is authorized by the algorithm; and
denying the access request in the event the access request is unauthorized.- View Dependent Claims (9, 10, 11, 12)
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13. In a microcontroller, a method of controlling secure access to memory, comprising:
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in response to a request to change a security rule for a block of memory, determining if the change in the security rule for the block of memory is authorized; and denying the request in the event the request is unauthorized, wherein the security rule comprises one of a plurality of security levels assigned to the block of memory. - View Dependent Claims (14, 15)
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Specification