US 12,250,303 B2
Protection of a cryptographic operation
Guilhem Assael, Pourrieres (FR)
Assigned to STMICROELECTRONICS (ROUSSET) SAS, Rousset (FR)
Filed by STMICROELECTRONICS (ROUSSET) SAS, Rousset (FR)
Filed on Aug. 18, 2022, as Appl. No. 17/820,843.
Claims priority of application No. 2109096 (FR), filed on Aug. 31, 2021.
Prior Publication US 2023/0074513 A1, Mar. 9, 2023
Int. Cl. H04L 9/08 (2006.01); G06F 7/72 (2006.01)
CPC H04L 9/0877 (2013.01) [G06F 7/725 (2013.01)] 26 Claims
OG exemplary drawing
 
1. A method, comprising:
executing an application invoking a cryptographic operation; and
performing the invoked cryptographic operation, the performing the invoked cryptographic operation including:
multiplying, using cryptographic circuitry, a point, belonging to a mathematical set with a group structure, by a scalar; and
protecting, using the cryptographic circuitry, the scalar during the multiplying, the multiplying and protecting including:
dividing the scalar into a plurality of groups formed of a same number w of digits, w being greater than or equal to 2; and
executing, for each group of digits, of a sequence of operations on the point, the sequence of operations having a same sequence for each group of digits, at least one of the operations executed for each of the groups of digits being a dummy operation,
wherein the same sequence of operations comprises:
the execution, w times, of a double operation;
the execution of an add operation; and
the execution, (w−1) times, of the double operation.