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.
Patent No.:
Date of Patent:
Jul. 31, 2012
Filed:
Nov. 13, 2003
Marc Joye, Saint Zacharie, FR;
Karine Villegas, Gemenos, FR;
Marc Joye, Saint Zacharie, FR;
Karine Villegas, Gemenos, FR;
Gemalto SA, Meudon, FR;
Abstract
The invention relates to a cryptographic method involving an integer division of type q=a div b and r=a mod b, wherein a is a number of m bits, b is a number of n bits, with n being less than or equal to m, and bbeing non-null and the most significant bit of b. In addition, each iteration of a loop subscripted by i, which varies between 1 and m−n+1, involves a partial division of a word A of n bits of number a by number b in order to obtain one bit of quotient q. According to the invention, the same operations are performed with each iteration, regardless of the value of the quotient bit obtained. In different embodiments of the invention, one of the following is also performed with each iteration: the addition and subtraction of number b to/from word A; the addition of number b or a complementary number /b of b to word A; or a complement operation at 2of an updated datum (b or /b) or a dummy datum (c or /c) followed by the addition of the datum updated with word A.