Encryption device, encryption method, and computer program

Details Encryption device, encryption method, and computer program Encryption device, encryption method, and computer program

2005-08-30

2010-06-29

Abrishamkar, Kaveh (Department: 2431)

Cryptography

Particular algorithmic function encoding

C380S037000, C713S189000

Reexamination Certificate

active

07747011

ABSTRACT:
The invention realizes a high-security cryptographic processing apparatus that increases difficulty in analyzing its key and a method therefor. In Feistel-type common-key-block cryptographic processing that repeatedly executes an SPN-type F-function having the nonlinear conversion section and the linear conversion section over a plurality of rounds, Linear conversion processing of an F-function corresponding to each of the plurality of rounds is carried out by linear conversion processing that applies square MDS (Maximum Distance Separable) matrices. The invention uses a setting that arbitrary m column vectors included in inverse matrices of square MDS matrices being set up at least in consecutive even-numbered rounds and in consecutive odd-numbered rounds, respectively, constitute a square MDS matrix. This structure realizes cryptographic processing whereby resistance to linear cryptanalysis attacks in the common-key-block cipher is improved.

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Jérôme Lacan, “Constructions de codes MDS”, (travail realise conjointement avec Jérôme Fimes), DMI : Département Mathématiques appliquées et Informatique, May 24, 2004, XP007907064, 45 pages.
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