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:
May. 26, 2015
Filed:
Nov. 16, 2011
Markus Bockes, Munich, DE;
Jurgen Pulkus, Munich, DE;
Markus Bockes, Munich, DE;
Jurgen Pulkus, Munich, DE;
GIESECKE & DEVRIENT GMBH, Munich, DE;
Abstract
A method in a portable data carrier for executing a cryptographic operation on security-relevant data comprises a step of determining a remainder (r) of a dividend (a) modulo a divisor (b). In so doing, the remainder (r) is determined iteratively by means of a division device of the data carrier. In each iteration there is carried out a Montgomery multiplication with the divisor (b) as the modulus and an additive linkage of an output value of the Montgomery multiplication with a coefficient (a) derived from the dividend (a) and associated with the respective iteration. The Montgomery multiplication is carried out here by means of a multiplication device of the data carrier, preferably a corresponding coprocessor. The Montgomery multiplication of a subsequent iteration receives a result of a preceding iteration as an input value.