Patent ID: 6738478
Filing Date: 2004-05-18
Classification: G06F

Abstract:
A method of computing a multiple k of a point P on an elliptic curve defined over a field in a processor which generates distinct power signatures for adding and doubling operations, said method comprising the steps of:a) representing the number k as binary vector of bits ki; b) forming an ordered pair of points P1 and P2, wherein the points P1 and P2 differ at most by P; and c) selecting each of said bits ki in sequence; and for each of said bits ki; i) upon ki being a zero, computing a new set of points P1â€², P2â€² by first doubling the first point P1 to generate said point P1â€² and thereby producing a first power signature, and subsequently adding the points P1 and P2 to generate the point P2â€² and thereby producing a second power signature distinct from said first power signature; or ii) upon ki being a one, computing a new set of points P1â€², P2â€² by first doubling the second point P2 to generate the point P2â€² and thereby producing said first power signature; and subsequently adding the points P1 and P2 to produce the point P1â€², and thereby producing said second power signature; whereby said doubles or adds arc always performed in the same order for each of said bits ki, thereby producing a consistent power signature waveform and minimizing a timing attack on said method.