Method and device for protecting a memory against attacks by error injection
First Claim
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1. A method for securing a data memory in which individually read-accessible binary words are saved, comprising:
- defining in the memory a memory zone covering a plurality of words;
receiving a write request to write a new word in the memory zone;
in response to receiving the write request, reading all words in a set of words present in the memory zone; and
simultaneously calculating a first current cumulative signature and a second current cumulative signature as a function of the words read in the memory zone, the calculating of the second current cumulative signature comprising replacing on-the-fly with the new word, a write target word, of the words read, that is intended to be replaced in the memory with the new word, wherein the words in the memory zone are read during the calculating of the current cumulative signatures, at a faster rate than a rate of writing the write target word in the memory.
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Abstract
A method secures a memory in which individually read-accessible binary words are saved. The method includes defining a memory zone covering a plurality of words, calculating a cumulative signature according to all of the words in the memory zone, and storing the cumulative signature as an expected signature of the memory zone to check the integrity of data read in the memory. The method can be applied to the securing of smart cards.
23 Citations
31 Claims
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1. A method for securing a data memory in which individually read-accessible binary words are saved, comprising:
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defining in the memory a memory zone covering a plurality of words; receiving a write request to write a new word in the memory zone; in response to receiving the write request, reading all words in a set of words present in the memory zone; and simultaneously calculating a first current cumulative signature and a second current cumulative signature as a function of the words read in the memory zone, the calculating of the second current cumulative signature comprising replacing on-the-fly with the new word, a write target word, of the words read, that is intended to be replaced in the memory with the new word, wherein the words in the memory zone are read during the calculating of the current cumulative signatures, at a faster rate than a rate of writing the write target word in the memory. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A device for securing a data memory in which individually read-accessible binary words are stored, comprising:
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means for locating a memory zone of the memory covering a plurality of words; means for reading all words of a set of words present in the memory zone; a first signature calculation circuit to calculate a first current cumulative signature as a function of the words read in the memory zone; means for intercepting a command for writing a new word in the memory zone; a second signature calculation circuit for calculating a second current cumulative signature as a function of the words read in the memory zone; and means for simultaneously applying, in response to the write request, the words read to the first signature calculation circuit for calculating the first current cumulative signature and to the second signature calculation circuit for calculating the second current cumulative signature by replacing on-the-fly with the new word, a write target word, of the words read, that is intended to be replaced in the memory with the new word, wherein the memory zone is scanned during the current cumulative signature calculations, at a faster rate than a rate of writing the write target word in the memory. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A method for securing a data memory in which individually read-accessible words are saved, comprising:
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defining in the memory a memory zone storing a set of words; receiving a write request to write a new word in the memory zone in place of a write target word of the set; in response to receiving the write request, reading all of the words of the set; and simultaneously calculating a first current cumulative signature and a second current cumulative signature, the first current cumulative signature being calculated as a function of all of the words in the set, and the second current cumulative signature being calculated as a function of the new word and all of the words in the set except for the write target word, wherein the new memory zone is scanned during the current cumulative signature calculations, at a faster rate than a rate of writing in the memory. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27)
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28. A device to secure a data memory, the device comprising:
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a first signature calculator; a second signature calculator; and a controller configured to respond to a request to replace a target word in a set of words in a defined memory zone with a new word by simultaneously causing; the first signature calculator to calculate a first cumulative signature based on the set of words in the defined memory zone; and the second signature calculator to calculate a second cumulative signature based on the set of words in the defined memory zone with the target word replaced with the new word, wherein the memory zone is scanned during the current cumulative signature calculations, at a faster rate than a rate of writing in the memory. - View Dependent Claims (29, 30)
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31. A system, comprising:
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a data memory; a device configured to secure the data memory, the device comprising; a first signature calculator; a second signature calculator; and a controller configured to respond to a request to replace a target word in a set of words in a defined memory zone with a new word by simultaneously causing; the first signature calculator to calculate a first cumulative signature based on the set of words in the defined memory zone; and the second signature calculator to calculate a second cumulative signature based on the set of words in the defined memory zone with the target word replaced with the new word, wherein the memory zone is scanned during the current cumulative signature calculations, at a faster rate than a rate of writing in the memory.
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Specification