Patent ID: 8744074

Claim:
A method for calculating an exponentiation, the method being resistant against fault-attacks and comprising the steps, in a device, of: obtaining a RSA private key object, the RSA private key object being associated with a matching public exponent; obtaining a result of an exponentiation using the RSA private key object; obtaining the matching public exponent; and verifying, using the matching public exponent, that the result of the exponentiation is correct; wherein, in standard mode: the RSA private key object comprises the RSA modulus N, the matching public exponent e being obtained by extraction from the RSA modulus N in which it is embedded; and wherein, in CRT mode: the RSA private key object comprises the factors of the RSA modulus N, the matching public exponent e being obtained by extraction from one of the factors of the RSA modulus N or from a product of the factors of the RSA modulus N.