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. 27, 2004
Filed:
Sep. 14, 2000
Masayuki Kanda, Tokyo, JP;
Youichi Takashima, Tokyo, JP;
Kazumaro Aoki, Tokyo, JP;
Hiroki Ueda, Tokyo, JP;
Kazuo Ohta, Tokyo, JP;
Tsutomu Matsumoto, Yokohama, JP;
Abstract
A plurality of round processing parts ( ) are provided each of which contains a nonlinear function part ( ), and each nonlinear function part ( ) comprises: a first key-dependent linear transformation part ( ) which performs a linear transformation based on a subkey; a splitting part ( ) which splits the output from the first key-dependent linear transformation part into n pieces of subdata; a first nonlinear transformation part ( ) which nonlinearly transforms those pieces of subdata, respectively; a second key-dependent linear transformation part ( ) which linearly transforms those nonlinearly transformed outputs based on a subkey and outputs n pieces of transformed subdata; a second nonlinear transformation part ( ) which nonlinearly transforms those transformed subdata; and a combining part ( ) which combines the nonlinearly transformed outputs. An n×n matrix, which represents the linear transformation in the second key-dependent linear transformation part ( ), is formed by n vectors whose Hamming weights are equal to or larger than T−1 for a security threshold T, thereby increasing the invulnerability against differential cryptanalysis and linear cryptanalysis.