A countermeasure method in an electronic component using a secret key algorithm K on an input message M executes an operation O.sub.PN(D) on input data D. A random value, of one first random information U, is generated that is of identical size as the input information D. A second random information V, is calculated by performing an exclusive OR operation between the input information and the first random information U. The operation O.sub.PN or the sequence of operations are successively executed on the first input information U and to the second random information V, supplying respectively a first random result O.sub.PN(U) and a second random result O.sub.PN(V).