COUNTER-MEASUREMENT METHODS IN AN ELECTRONIC COMPONENT USING AN ELLIPTICAL CURVE-TYPE PUBLIC KEY CRYTOGRAPHY ALGORITHM

摘要

The invention relates to a countermeasure method in an electronic component implementing an elliptical curve based public key cryptography algorithm, comprising the calculation of a new decryption integer d' such as the decryption of an encrypted message with the aid of a decryption algorithm on the basis of a private key d and the number of points n of said elliptical curve whereby the same result is achieved with d' as with d, by performing the operation Q=d*P, whereby P is a point of the curve. The inventive measure is characterized in that it comprises four steps: 1) a security parameter s is determined, whereby in practice it is impossible to take s as a neighbour of 30, 2) a random number k ranging from 0-21s is drawn, 3) the integer d'=d+k*n is calculated, 4) Q=d'.P is calculated.