Countermeasure method for an electronic component implementing an elliptic curve cryptography algorithm

Abstract

The subject of the invention is a countermeasure method for an electronic component implementing a public-key cryptography algorithm on an elliptic curve E defined over a fieldand comprising an iterative scalar multiplication operation making it possible to obtain a point [k]P on the basis of a point P of the curve E and of an integer k that must remain secret, the electrical consumption of the electronic component being dependent on the value taken by at least one so-called critical point used during said operation to iteratively determine the point [k]P. The method comprises: a step () of providing at least one power of a predefined non-zero constant element c ofdifferent from one; a step () of initializing the coordinates of the at least one critical point to a predefined value; a step () implementing the scalar multiplication operation, the coordinates associated with at least one critical point being modified at each iteration by multiplying at least one of the coordinates of this point by the at least one power of the element c obtained in the providing step ().