Nippon Telegraph and Telephone Corporation

Mitsubishi Denki Kabushiki Kaisha

Nippon Telegraph and Telephone Public Corporation

Kazumaro Aoki

Masayuki Kanda

Shiho Moriai

Mitsuru Matsui

Junko Nakajima

Toshio Tokita

Hiroki Ueda

Kazuo Ohta

Youichi Takashima

Tsutomu Matsumoto

It is desired to share one circuit by an encryption unitand a decryption unit. A normal data transformation unit (FL)and an inverse data transformation unit (FL)are located at point symmetry on a non-linear data transformation unit, and a normal data transformation unit (FL)and an inverse data transformation unit (FL)are located at point symmetry on the non-linear data transformation unit. Therefore, the encryption unitand the decryption unitcan be configured using the same circuits.

Block encryption device using auxiliary conversion

Block cipher apparatus using auxiliary transformation

Block cipher using auxiliary transformation

In the evaluation of the randomness of an S-box, measures of resistance to higher order cryptanalysis, interpolation cryptanalysis, partitioning cryptanalysis and differential-linear cryptanalysis and necessary conditions for those measures to have resistance to each cryptanalysis are set, then for functions as candidates for the S-box, it is evaluated whether one or all of the conditions are satisfied, and those of the candidate functions for which one or all of the conditions are satisfied are selected as required. It is also possible to further evaluate the resistance of such selected functions to at least one of differential cryptanalysis and linear cryptanalysis and select those of the candidate functions which are resistant to at least one of the cryptanalyses as required.

Method and apparatus for evaluating the strength of an encryption

Permuted data (u', u&#x2032;, . . . , u&#x2032;) of input data (u, u, . . . , u) expressed by the relationship

Method and apparatus for permuting input data and recording medium having stored thereon a program for executing permutation

In an inverse calculation, x is road out of a storage means, [x/2] is calculated and stored therein as b, a lent significant bit of b is stored as a, [(ax+b)/2] is calculated and stored as updated b, and low-order two bits of x are stored as y. Then, for i=1, 2, . . . , n&#x2212;1, by is calculated, a is updated with &#x2212;by, [(b+ax)/(2^(2))] is calculated and stored as updated b, and y+a2^(2) is calculated and stored as updated y, where y is road out as the result of inverse calculation.

Inverse calculation apparatus and recording medium having stored thereon a program for executing inverse calculation

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&times;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&minus;1 for a security threshold T, thereby increasing the invulnerability against differential cryptanalysis and linear cryptanalysis.

Data converter and recording medium on which program for executing data conversion is recorded

In a method for permuting and dividing 16 pieces of k-bit data held in 4k-bit long registers T . T , T and T , k being an integer, the data of each register T is ANDed with a desired one of mask data (00ffff00), (ff0000ff), (0000ffff) and (ffff0000), and such ANDs are ORed to obtain desired permuted data.

Method and apparatus for data permutation/division and recording medium with data permutation/division program recorded thereon

A scheme for arithmetic operations in finite field and group operations over elliptic curves capable of realizing a very fast implementation. According to this scheme, by using a normal basis [.alpha. .alpha.+1], the multiplicative inverse calculation and the multiplication in the finite field GF(2.sup.2n) can be realized as combinations of multiplications, additions and a multiplicative inverse calculation in the subfield GF(2.sup.n). Also, by using a standard basis [1.alpha.], the multiplication, the square calculation, and the multiplicative inverse calculation in the finite field GF(2.sup.2n) can be realized as combinations of multiplications, additions and a multiplicative inverse calculation in the subfield GF(2.sup.n). These arithmetic operations can be utilized for calculating rational expressions expressing group operations over elliptic curves that are used in information security techniques such as elliptic curve cryptosystems.

Growing community of inventors

Tokyo, Japan

Kazumaro Aoki