Proposed A Permutation and Substitution Methods of Serpent Block Cipher

Intisar Abid Yousif

doi:10.30526/32.2.2120

Abstract

Block cipher technique is one of cryptography techniques to encrypt data block by block. The Serpent is one of AES candidates. It encrypts a 128-bit block by using 32 rounds of a similar calculation utilizing permutations and substitutions. Since the permutations and substitutions of it are static. Then this paper proposes dynamic methods for permutation, substitution and key generation based on chaotic maps to get more security. The proposed methods are analyzed and the results showed that they were able to exceed the weakness resulting from the use of static permutations and substitutions boxes in the original algorithm and also can reduce number of rounds and time usage compared with a classical Serpent block cipher algorithm

Highlights

Chaos theory is an awesome dynamic part in current cryptography
The Data Encryption Standard (DES) algorithm endorsed its shortcoming against a great deal of cryptanalytic assault; require a safe calculation has been issued by the US National Institute of Standards and Technology, to be known as the Advanced Encryption Standard (AES)
The block cipher Serpent was outlined by Anderson, Biham and Knudsen to be contender for AES [4]. while, Daemen and Rijmen outlined the block cipher Rijndael

Summary

Introduction

Chaos theory is an awesome dynamic part in current cryptography. The principle highlights of utilizing chaos theory in numerous cryptosystems can be finished up on its affectability to starting conditions parameter and irregular conduct settings that accomplish the essential Shannon prerequisites of disarray and dissemination. This paper presents a proposed modification of Serpent algorithm by replacing the static permutation and substitution with dynamical properties using logistic chaos map and standard map. In decryption algorithm reverses an encryption block diagram processes to recover a plaintext [25]

Overview of logistic map and standard map Logistic map

The proposed round keys

Security and Statistical Analysis Brute Force Attack

Conclusion