Cryptanalyze and design strong S-Box using 2D chaotic map and apply to irreversible key expansion
This addresses security vulnerabilities in cryptographic systems for encryption applications, though it appears incremental as it builds on existing ciphers.
The paper tackled weaknesses in S-Boxes and reversible key expansion in AES and SM4 by designing a strong S-Box using a 2D chaotic map and an irreversible key expansion algorithm, with security analysis demonstrating effectiveness.
Cryptanalysis result of key expansion algorithms in AES and SM4 revealed that, (1) there exist weaknesses in their S-Boxes, and (2) the round key expansion algorithm is reversible, i.e., the initial key can be recovered from any round key, which may be an exploitable weakness by attacker. To solve these problems, first we constructed a non-degenerate 2D exponential hyper chaotic map (2D-ECM), derived the recursion formula to calculate the number of S-Boxes that satisfied three conditions, and designed a strong S-Box construction algorithm without weakness. Then based on 2D-ECM and S-Box, we designed an irreversible key expansion algorithm, to transform the initial key into independent round keys, to make the initial key can not be recovered from any round key. Security and statistical analysis demonstrated the flexible and effectiveness of the proposed irreversible key expansion algorithm.