The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.

The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.

Date of Patent:
Jun. 08, 2021

Filed:

May. 30, 2019
Applicant:

Idemia France, Courbevoie, FR;

Inventors:

Thomas Chabrier, Courbevoie, FR;

Gilles Piret, Courbevoie, FR;

Assignee:

IDEMIA FRANCE, Courbevoie, FR;

Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G06F 7/72 (2006.01); H04L 9/30 (2006.01);
U.S. Cl.
CPC ...
G06F 7/721 (2013.01); G06F 7/723 (2013.01); G06F 7/725 (2013.01); G06F 7/727 (2013.01); H04L 9/302 (2013.01);
Abstract

In a method for determining the modular inverse of a number, successive iterations are applied to two pairs each including a first variable and a second variable, such that at the end of each iteration and for each pair, the product of the second variable and of the number is equal to the first variable modulo a given module. Each iteration includes at least one division by two of the first variable of a first pair or of a second pair, or a combination of the first variable of the first pair and of the first variable of the second pair by addition or subtraction. At least some of the iterations including a combination by addition or subtraction include a step of storing the result of the combination in the first variable of a pair determined randomly from among the first pair and the second pair. An associated cryptographic processing device is also described.


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