Countermeasure method in an electronic component using a public key cryptography algorithm on an elliptic curve
AssigneeGemplus
InventorHelena Handschuh
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Abstract
The present invention concerns a countermeasure method in an electronic component using a public key cryptography algorithm based on the use of elliptic curves. From a private key d and a number of points n on an elliptic curve, a new deciphering integer d′ is calculated. The present invention applies particularly to any existing electronic component, such as a smart card.
Claims13
A countermeasure method in an electronic component using a public key cryptography algorithm based on the use of elliptic curves in which a private key d and the number of points n on an elliptic curve are used to calculate a new deciphering integer d′ such that the deciphering of any message, by means of a deciphering algorithm, with d′ makes it possible to obtain the same result as with d, by performing the operation Q=d.P, where P is a point on the curve to which the scalar multiplication algorithm is applied, said method comprising the following steps:
- 1) taking a random value r with the same size as d;
- 2) calculating an integer d′ such that d′=d+r;
- 3) Performing a scalar multiplication operation whose result is a point Q′ on the curve such that Q′=d′.P;
- 4) Performing a scalar multiplication operation whose result is a point S on the curve such that S=r.P;
- and
- 5) calculating the point Q on the curve such that Q=Q′−S.
An electronic component having an integrated circuit which executes a public key cryptography algorithm based on the use of elliptic curves in which a private key d and the number of points n on an elliptic curve are used to calculate a new deciphering integer d′ such that the deciphering of any message, by means of a deciphering algorithm, with d′ makes it possible to obtain the same result as with d, by performing the operation Q=d.P, where P is a point on the curve to which the scalar multiplication algorithm is applied, said circuit executing the following steps:
- 1) taking a random value r with the same size as d;
- 2) calculating an integer d′ such that d′=d+r;
- 3) Performing a scalar multiplication operation whose result is a point Q′ on the curve such that Q′=d′.P;
- 4) Performing a scalar multiplication operation whose result is a point S on the curve such that S=r.P;
- and
- 5) calculating the point Q on the curve such that Q=Q′−S.
Dependencies are inferred from the claim text.