Gesicherte Durchführung eines Kryptografischen Prozesses

Details

Veröffentlichungs-Nr.

EP3998738

Aktenzeichen

EP21193193

Anmeldetag

26. August 2021

Veröffentlichung

1. Oktober 2025

Erteilung

1. Oktober 2025

Rechtsraum

EP

IPC

H04L9/00H04L9/06

Abstract

A method of performing a cryptographic process in a secured manner, wherein the cryptographic process generates output data based on input data, the generating of the output data involving generating a value y based on an amount of data x, the value y representing a combination, according to a linear transformation L, of respective outputs from a plurality of S-boxes Sn (n = 0, ..., N - 1) for integer N > 1, wherein each S-box Sn (n = 0, ..., N - 1) implements a respective function Hn that is either (a) the composition of a respective first function Fn and a respective linear or affine second function Gn so that Hn = Gn ∘ Fn, or (b) the composition of a respective first function Fn, a respective linear or affine second function Gn and a respective third function Wn so that Hn = Gn ∘ Fn ∘ Wn, wherein the method comprises: performing a first processing stage and a second processing stage to generate the value y based on the amount of data x, wherein: the first processing stage uses a plurality of first lookup tables to generate respective outputs, each output being based on at least part of the amount of data x, wherein, for each S-box Sn (n = 0, ..., N - 1), the respective first function Fn is implemented by a corresponding first lookup table; and the second processing stage combines outputs from a plurality of second lookup tables to generate the value y, wherein the input to each second lookup table is formed from the output of a plurality of the first lookup tables, and wherein the set of second lookup tables is based on the second functions Gn (n = 0, ..., N - 1) and the linear transformation L.

Anmelder

Firma

Irdeto B.V.

Land

🇳🇱 Niederlande

Fachgebiete