Detecting chip alterations with light emission
First Claim
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1. A method comprising:
- obtaining a light emission map of a circuit to be tested for alterations;
obtaining a light emission map of a reference circuit; and
comparing an image of said light emission map of said circuit to be tested with an image of said light emission map of said reference circuit, to determine presence of said alterations;
wherein said comparing step comprises at least one of performing image processing to subtract the image of said light emission map of said circuit to be tested from the image of said light emission map of said reference circuit, performing image processing to differentiate the image of said light emission map of said circuit to be tested from the image of said light emission map of said reference circuit, and performing image processing to apply a two-dimensional correlation function to correlate the image of said light emission map of said circuit to be tested and the image of said light emission map of said reference circuit;
wherein said light emission map of said reference circuit is obtained by simulation;
wherein said simulation comprises;
calculating a leakage current for each of a plurality of devices of said reference circuit, based on a layout database and a state vector;
dividing said reference circuit into a plurality of sub-Nyquist tiles;
summing said leakage current for each of said devices in each given one of said sub-Nyquist tiles to obtain a resultant grid; and
oversampling said resultant grid, wherein said oversampling comprises convolving an oversampling window with said sub-Nyquist tiles to provide smoothing; and
wherein said step of obtaining said light emission map of said circuit to be tested, said step of obtaining said light emission map of said reference circuit, and said step of comparing are performed by one or more hardware devices including a memory and at least one processor, coupled to said memory.
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Abstract
An emission map of a circuit to be tested for alterations is obtained by measuring the physical circuit to be tested. An emission map of a reference circuit is obtained by measuring a physical reference circuit or by simulating the emissions expected from the reference circuit. The emission map of the circuit to be tested is compared with the emission map of the reference circuit, to determine presence of alterations in the circuit to be tested, as compared to the reference circuit.
31 Citations
19 Claims
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1. A method comprising:
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obtaining a light emission map of a circuit to be tested for alterations; obtaining a light emission map of a reference circuit; and comparing an image of said light emission map of said circuit to be tested with an image of said light emission map of said reference circuit, to determine presence of said alterations; wherein said comparing step comprises at least one of performing image processing to subtract the image of said light emission map of said circuit to be tested from the image of said light emission map of said reference circuit, performing image processing to differentiate the image of said light emission map of said circuit to be tested from the image of said light emission map of said reference circuit, and performing image processing to apply a two-dimensional correlation function to correlate the image of said light emission map of said circuit to be tested and the image of said light emission map of said reference circuit; wherein said light emission map of said reference circuit is obtained by simulation; wherein said simulation comprises; calculating a leakage current for each of a plurality of devices of said reference circuit, based on a layout database and a state vector; dividing said reference circuit into a plurality of sub-Nyquist tiles; summing said leakage current for each of said devices in each given one of said sub-Nyquist tiles to obtain a resultant grid; and oversampling said resultant grid, wherein said oversampling comprises convolving an oversampling window with said sub-Nyquist tiles to provide smoothing; and wherein said step of obtaining said light emission map of said circuit to be tested, said step of obtaining said light emission map of said reference circuit, and said step of comparing are performed by one or more hardware devices including a memory and at least one processor, coupled to said memory. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 19)
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12. An apparatus comprising:
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means for obtaining a light emission map of a circuit to be tested for alterations; means for obtaining a light emission map of a reference circuit; and means for comparing an image of said light emission map of said circuit to be tested with an image of said light emission map of said reference circuit, to determine presence of said alterations; wherein said means for comparing comprises at least one of means for performing image processing to subtract the image of said light emission map of said circuit to be tested from the image of said light emission map of said reference circuit, means for performing image processing to differentiate the image of said light emission map of said circuit to be tested from the image of said light emission map of said reference circuit, and means for performing image processing to apply a two-dimensional correlation function to correlate the image of said light emission map of said circuit to be tested and the image of said light emission map of said reference circuit; wherein said means for obtaining said light emission map of said reference circuit comprises; means for calculating a leakage current for each of a plurality of devices of said reference circuit, based on a layout database and a state vector; means for dividing said reference circuit into a plurality of sub-Nyquist tiles; means for summing said leakage current for each of said devices in each given one of said sub-Nyquist tiles to obtain a resultant grid; and means for oversampling said resultant grid, wherein said oversampling comprises convolving an oversampling window with said sub-Nyquist tiles to provide smoothing. - View Dependent Claims (13)
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14. An apparatus comprising:
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a memory; at least one processor, coupled to said memory, said processor being operative to; obtain a light emission map of a circuit to be tested for alterations; obtain a light emission map of a reference circuit; compare an image of said light emission map of said circuit to be tested with an image of said light emission map of said reference circuit, to determine presence of said alterations; and at least one of perform image processing to subtract the image of said light emission map of said circuit to be tested from the image of said light emission map of said reference circuit, perform image processing to differentiate the image of said light emission map of said circuit to be tested from the image of said light emission map of said reference circuit, and perform image processing to apply a two-dimensional correlation function to correlate the image of said light emission map of said circuit to be tested and the image of said light emission map of said reference circuit; and an emission prediction module embodied in a computer readable storage medium, said at least one processor being operative to execute said emission prediction module to obtain said light emission map of said reference circuit; wherein said processor is operative to execute said emission prediction module by; calculating a leakage current for each of a plurality of devices of said reference circuit, based on a layout database and a state vector; dividing said reference circuit into a plurality of sub-Nyquist tiles; summing said leakage current for each of said devices in each given one of said sub-Nyquist tiles to obtain a resultant grid; and oversampling said resultant grid, wherein said oversampling comprises convolving an oversampling window with said sub-Nyquist tiles to provide smoothing. - View Dependent Claims (15, 16)
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17. A computer program product comprising a non-transitory computer readable recordable storage medium including computer usable program code, the computer program product including:
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computer usable program code for obtaining a light emission map of a circuit to be tested for alterations; computer usable program code for obtaining a light emission map of a reference circuit; and computer usable program code for comparing an image of said light emission map of said circuit to be tested with an image of said light emission map of said reference circuit, to determine presence of said alterations; and computer usable program code for at least one of performing image processing to subtract the image of said light emission map of said circuit to be tested from the image of said light emission map of said reference circuit, performing image processing to differentiate the image of said light emission map of said circuit to be tested from the image of said light emission map of said reference circuit, and performing image processing to apply a two-dimensional correlation function to correlate the image of said light emission map of said circuit to be tested and the image of said light emission map of said reference circuit; wherein said computer usable program code for obtaining said light emission map of said reference circuit comprises; computer usable program code for calculating a leakage current for each of a plurality of devices of said reference circuit, based on a layout database and a state vector; computer usable program code for dividing said reference circuit into a plurality of sub-Nyquist tiles; computer usable program code for summing said leakage current for each of said devices in each given one of said sub-Nyquist tiles to obtain a resultant grid; and computer usable program code for oversampling said resultant grid, wherein said oversampling comprises convolving an oversampling window with said sub-Nyquist tiles to provide smoothing. - View Dependent Claims (18)
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Specification