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:
Oct. 26, 2010
Filed:
Feb. 24, 2005
Marc Girault, Caen, FR;
David Lefranc, Cormeilles-en-Parisis, FR;
Marc Girault, Caen, FR;
David Lefranc, Cormeilles-en-Parisis, FR;
France Telecom, Paris, FR;
Abstract
A method and device for performing a cryptographic operation by a device controlled by a security application executed outside thereof in which a cryptographic value (y) is produced a calculation comprising at least one multiplication between first and second factors containing a security key (s) associated with the device and a challenge number (c) provided by the security application. The first multiplication factor comprises a determined number of bits (L) in a binary representation and the second factor is constrained in such a way that it comprises, in a binary representation, several bits at 1 with a sequence of at least L−1 bits at 0 between each pair of consecutive bits to 1 while the multiplication is carried out by assembling the binary versions of the first factor shifted according to positions of the bits at 1 of the second factor, respectively.