| abstract |
The present invention relates to a method of testing a circuit, in which when a circuit executes one of a set of distinct cryptographic operations to be applied to confidential data, a plurality of sets of values containing values of the physical quantity associated with the activity of the circuit to be tested Selecting at least a first subset from each set of values, for each set of values, applying to the values of a first subset of the set of values to form a set of occurrence counts of the set of values by the processing unit Counting the number of occurrences of the value transformed by the first transcription function, calculating partial work results for each of the possible values of each task and confidential data of the working set, Value or an equivalent operation, the partial operation result having the same conversion value generated from the application of the second transfer function (CH), which is obtained by adding all the sets of occurrence counts corresponding to the tasks of the task, and merging the cumulative occurrence counts of the cumulative occurrence count sets (HT) according to the selected merge method, and And analyzing the merged cumulative occurrence count sets HTR1 to determine a portion of the confidential data. |