Block encryption apparatus, block encryption method and program

Abstract

Pseudo randomness and strong pseudo randomness are efficiently achieved in block encryption based on a generalized Feistel network. When a plaintext consisting of k blocks each having n bits is encrypted, Feistel substitution is applied to the plaintext with respect to each 2n bits. Then, substitution in units of blocks is applied thereto which is based on a binary de Bruijn graph symmetrically colored in accordance with a rule called type-2 branch coloration. One round is defined as a combination of one operation of the Feistel substitution and one operation of the substitution in the units of blocks. A ciphertext is outputted after this round is repeated a predetermined number of times.

Description

technical field [0001] [Remarks for related application] [0002] The present invention claims the priority of Japanese Patent Application: Japanese Patent Application No. 2009-246307 (applied on October 27, 2009), and the entire description content of this application is cited and described in this specification. [0003] The present invention relates to a block encryption device, a block encryption method, and a program, and more particularly, to a block encryption apparatus, a block encryption method, and a program using Feistel permutation. Background technique [0004] The so-called block encryption is a kind of common key encryption, which is a technique of encrypting plaintext (plaintext) of a certain block size using a key (key). As a typical configuration method of block encryption, there is a method using Feistel permutation. In Feistel permutation, one block is divided into two unit blocks A and B, one unit block A is input to a non-linear function with a key ca...

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Problems solved by technology

Here, Mix is ​​a linear transformation of kn bits, but since Mix does not have different inter-block influences under the permutation based on n-bit block units, it is not safe under any circumstances.

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