Patent ID: 8457303

Claim:
A method for checking the correctness of a cryptographic operation on a first elliptic curve E(Z/pZ), the method being resistant against fault attacks and comprising the steps of: obtaining, by a processor, a third elliptic curve E^(Z/pr 2 Z)≡E(Z/pZ)×E(Z/r 2 Z) given by Chinese remaindering from the first elliptic curve E(Z/pZ) and a second elliptic curve E(Z/r 2 Z), where r is an integer; performing the cryptographic operation on E^(Z/pr 2 Z) to obtain a first result; performing the cryptographic operation on E 1 (Z/r 2 Z), where E 1 (Z/r 2 Z) denotes the subset of points in E(Z/r 2 Z) that reduce modulo r to the identity element on E(Z/rZ), to obtain a second result; verifying that the first result and the second result are equal in E 1 (Z/r 2 Z); and if this is the case; outputting the first result of the operation in E^(Z/pr 2 Z) reduced modulo p.