Patent ID: 8873745

Claim:
A method for protecting a calculation on an elliptic curve, by an electronic circuit, wherein a point of an elliptic curve is multiplied by a digital value, the method comprising acts of: initializing a first variable with a first function of a random value; initializing at least a second variable with a second function of the point of the elliptic curve; performing a plurality of iterations, each iteration processing a one or more bits of a binary representation of the digital value, wherein each iteration comprises: a) subtracting, by the electronic circuit, from a first value of the first variable a multiple of said random value, wherein the first value of the first variable comprises a multiple of the point of the elliptic curve in addition to the multiple of the random value; and b) determining whether at least one bit of the one or more bits is equal to 1 and, in response to determining that the at least one bit is equal to 1, updating the first variable with a result of adding, by the electronic circuit, to a second value of the first variable a value of the second variable, wherein the value of the second variable is based on the point of the elliptic curve, after performing the plurality of iterations, subtracting from a third value of the first variable the random value.