Method and device to protect a cryptographic exponent

Abstract

Public-key cryptography allows putting into practice concepts of digital signatures and public-key key exchange; methods used on a daily basis in digital systems. A method generates a protected secret value k′ used as a first operand in a cryptographic group operation involving a base group element G of order n and including: generating random positive integers k1 and k2, that are strictly smaller than the order of the group element G due to a cryptographically secure random number generator, such that the generated random positive integers k1 and k2 do not share any divisor with the order n other than 1; generating the protected secret value k′ based on the generating random positive integers such as k′=k1*k2, the protected secret value k′ being used as a second operand in the group operation.

Dependencies are inferred from the claim text.