US 11,973,866 B2
Cryptographic processing method, related electronic device and computer program
Guillaume Barbu, Courbevoie (FR); Alberto Battistello, Courbevoie (FR); Luk Bettale, Courbevoie (FR); Nicolas Debande, Courbevoie (FR); Christophe Giraud, Courbevoie (FR); Sarah Lopez, Courbevoie (FR); and Franck Rondepierre, Courbevoie (FR)
Assigned to IDEMIA FRANCE, Courbevoie (FR)
Filed by IDEMIA France, Courbevoie (FR)
Filed on Jun. 22, 2021, as Appl. No. 17/354,494.
Claims priority of application No. 2006695 (FR), filed on Jun. 26, 2020.
Prior Publication US 2021/0409208 A1, Dec. 30, 2021
Int. Cl. H04L 9/08 (2006.01); G06F 7/72 (2006.01)
CPC H04L 9/0869 (2013.01) [G06F 7/721 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A cryptographic processing method comprising the determination, in a finite order group provided with an operation and from a first element (M) of this group, of a second element (Sp; P) equal to the combination, by means of said operation, of elements equal to the first element (M) and in number equal to a first number (dp), wherein said cryptographic processing method comprises the following steps:
obtaining (E10; E32) a second number (d″) determined by adding to the first number (dp) said order or a multiple of said order;
determining (E12; E30) a random number (a);
determining (E14; E34) a quotient (Q; q) and a remainder (R; r) using the Euclidean division of the second number (d″) by the random number (a);
obtaining (E16; E36) a third element (E1; I) equal to the combination, by means of said operation, of elements equal to the first element (M) and in number equal to the product of the quotient (Q; q) and the random number (a);
obtaining (E18; E38) a fourth element (E2; J) equal to the combination, by means of said operation, of elements equal to the first element (M) and in number equal to the remainder (R; r);
determining (E20; E40) the second element (Sp; P) by combining the third element (E1; I) and the fourth element (E2; J) by means of said operation.