Data securing method for e.g. chip card, involves placing output data in memory zone, copying data in memory zone into another memory zone, and replacing output data by another data corresponding to null value or random value

摘要

#CMT# #/CMT# The method involves applying a cryptographic operation (o1) to input data (A) for obtaining output data (B). The output data is placed in a memory zone (m-o). The data in the memory zone (m-o) is copied into another memory zone (m-i) different from the zone (m-o). The output data in the memory zone (m-o) is replaced by data (v) different from the output data. The data (v) corresponds to a null value or random value. #CMT#USE : #/CMT# Method for securing data during execution of function implementing operations e.g. cryptographic operation, in a securing device e.g. chip card (claimed). #CMT#ADVANTAGE : #/CMT# The replacement of the output data by another data and the utilization of different memory zones for the input data and the output data enable prevention of the access of the output data by attacking, thus protecting a secret key utilized for the cryptographic operation. #CMT#DESCRIPTION OF DRAWINGS : #/CMT# The drawing shows a block diagram representing execution of function. A : Input data B : Output data m-i, m-o : Memory zones o1 : Cryptographic operation v : Data #CMT#INDUSTRIAL STANDARDS : #/CMT# The cryptographic operation conforms to ISO/IEC FDIS 10116 standard.