REPRESENTATION CHANGE OF A POINT ON AN ELLIPTIC CURVE

摘要

An elliptic curve cryptographic system where point coordinates are transformed from a first coordinate system to a second coordinate system. The transformed coordinates are processed by field operations, which have been modified for operating on the transformed point coordinates. In some implementations, the point coordinates are transformed from an affine coordinate system to a projective coordinate system using a non- random value for the projective coordinate. In some implementations, the transformed projective representation of the point can be changed from a first representation of the point in projective coordinates to a second representation of the point in projective coordinates, where the projective coordinate used in the representation change is a random value. The teachings of the invention can be advantageously applied to the implementation of an elliptic curve public-key cryptography system that is secure against side-channel attacks.