A test method of a circuit, comprising: acquiring a plurality of value sets (Ci), each value set comprising values of a physical quantity or of logic signals, linked to the activity of a circuit to be tested when the circuit executes an operation (OPRK) of an operation set of distinct cryptographic operations applied to a same secret data, selecting at least a first subset (EC1i) in each value set (Ci), for each value set, counting by a processing unit occurrence numbers of values transformed by a first surjective function applied to the values (EC1i[j]) of the first subset of the value set, to form an occurrence number set (HT1, HT) for the value set, for each operation of the operation set, and each of the possible values (g) of a part of the secret data, computing by the processing unit a partial operation result, computing by the processing unit cumulative occurrence number sets, 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 value or equivalent value of the possible values of the part of the secret data, provide a partial operation result having a same transformed value resulting from the application of a second surjective function, merging according to a selected merging scheme, cumulative occurrence numbers in the cumulative occurrence number sets, or the combined occurrence numbers in the occurrence number sets before computing the cumulative occurrence numbers, and analyzing by the processing unit the merged cumulative occurrence number sets to determine the part of the secret data, knowing that if the secret data has leaked into the value sets, it is found in the cumulative occurrence number sets corresponding to the value of the part of the secret data. acquiring a plurality of value sets (Ci), each value set comprising values of a physical quantity or of logic signals, linked to the activity of a circuit to be tested when the circuit executes an operation (OPRK) of an operation set of distinct cryptographic operations applied to a same secret data, selecting at least a first subset (EC1i) in each value set (Ci), for each value set, counting by a processing unit occurrence numbers of values transformed by a first surjective function applied to the values (EC1i[j]) of the first subset of the value set, to form an occurrence number set (HT1, HT) for the value set, for each operation of the operation set, and each of the possible values (g) of a part of the secret data, computing by the processing unit a partial operation result, computing by the processing unit cumulative occurrence number sets, 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 value or equivalent value of the possible values of the part of the secret data, provide a partial operation result having a same transformed value resulting from the application of a second surjective function, merging according to a selected merging scheme, cumulative occurrence numbers in the cumulative occurrence number sets, or the combined occurrence numbers in the occurrence number sets before computing the cumulative occurrence numbers, and analyzing by the processing unit the merged cumulative occurrence number sets to determine the part of the secret data, knowing that if the secret data has leaked into the value sets, it is found in the cumulative occurrence number sets corresponding to the value of the part of the secret data.