CRYPTOGRAPHIC METHOD AND DEVICE FOR PROTECTING PUBLIC-KEY SOFTWARE AGAINST FAULT ATTACKS

摘要

The invention relates to an RSA cryptographic method and device using the Chinese remainder theorem (CRT) and comprising the following steps consisting in: 1. generating two random integers (r1, r2) which are used to construct two pairs of values (sp*, s1) and (sq*, s2) respectively, wherein s1 et s2 are test values; 2. generating a value s* for the final signature S by recombining values sp* and sq* using CRT; 3. generating two values c1 and c2 using a comparison function between s* and s1 and between s* and s2 respectively; 4. generating a result G that is a function of c1 and c2, having a value which, if c1=c2=1, is equal to 1, but, if not, is different from 1; and 5. producing the final signature S which is defined by S=f2(s*,G) mod(N), such that, if G=1, S=s* mod(N), but, if not, is different, and returning said signature to the exterior.