Detecting chip alterations with light emission

摘要

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.

主权项

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.