Method of testing the resistance of a circuit to a side channel analysis

A system for testing a circuit, the system comprising:

• a memory;
• and
• one or more processors configured to:
• acquire, via a measuring device, a plurality of measure sets, each measure set including measures of a physical quantity or logic signals acquired when a tested circuit executes an operation of an operation set of distinct cryptographic operations applied to a same first data stored by the tested circuit, the measures of the physical quantity or the logic signals being acquired by a measuring device coupled to the tested circuit;
• for each measure set, count occurrence numbers of transformed measure values resulting from a first surjective function applied to measures of the measure set, to form an occurrence number set for the measure set without including any time-related information;
• for each operation of the operation set, and each of possible data values of a part of the first data, compute a partial operation result;
• compute cumulative occurrence number sets of cumulative occurrence numbers, each cumulative occurrence number set being obtained by adding the occurrence number sets corresponding to the operations of the operation set, which, when applied to a same data value or equivalent data value of the possible data values of the part of the first data, provide one of the partial operation results having a same transformed result value resulting from an application of a second surjective function to the partial operation result;
• and
• analyzing the cumulative occurrence number sets to detect a data value of the part of the first data, wherein if the first data has leaked into the measure sets, the leakage of the first data is detected in the cumulative occurrence number sets which corresponds to the data value of the part of the first data.

A non-transitory computer-readable storage device carrying one or more sequences of instructions, which when executed by one or more processors, cause the one or more processors to:

• acquire, via a measuring device, a plurality of measure sets, each measure set including measures of a physical quantity or logic signals acquired when a tested circuit executes an operation of an operation set of distinct cryptographic operations applied to a same first data stored by the tested circuit;
• for each measure set, count occurrence numbers of transformed measure values resulting from a first surjective function applied to the measures of the measure set to form an occurrence number set for the measure set without including any time-related information,
• for each operation of the operation set, and each of possible data values of a part of the first data, compute a partial operation result;
• compute cumulative occurrence number sets of cumulative occurrence numbers, each cumulative occurrence number set being obtained by adding the occurrence number sets corresponding to the operations of the operation set, which when applied to a same data value or equivalent data value of the possible data values of the part of the first data, provide one of the partial operation results having a same transformed result value resulting from an application of a second surjective function to the partial operation result;
• and
• analyzing the cumulative occurrence number sets to detect a data value of the part of the first data, wherein if the first data has leaked into the measure sets, the leakage of the first data is detected in the cumulative occurrence number sets which corresponds to the data value of the part of the first data.