A countermeasure method in an electronic component which uses an encryption algorithm with public key type elliptic curve.

摘要

A countermeasure method in an electronic component applying an algorithm of public key cryptography type elliptic curve using the representation of the points of said elliptic curve in projective coordinates consisting in representing a point P of the elliptic curve by the data (X , Y, Z) such as x = X / Z 2 and y = Y / Z ^ 3, x and y are the data point of the elliptic curve in affine coordinates, said curve including n elements and is defined on a finite body GF ( p), p is a prime number, said curve having as an equation y ^ 2 = x ^ 3 + a x + b, or defined on a finite body GF (2 a n), said curve having as an equation y ^ 2 + x by y = x ^ 3 + a by x ^ 2 + b, where a and b are integers parameters set at the beginning, the process chooses a random integer representative among n possible elements in projective coordinates of the elliptic curve and is a modification of doubling operation points, said points addition and operation scalar multiplication, characterized in that the countermeasure method applies whatever the method or the algorithm noted below A, used to perform the doubling operation point, the process A is replaced by the method A 'applied' ' '3-step, using an input defined by a point P = (X1, Y1, Z1) represented in projective coordinates and an output defined by a point Q = (X2, Y2, Z2) represented by projective such coordinates as Q =