Deep Learning-Based Cryptanalysis of Lightweight Block Ciphers

Jaewoo So

doi:10.1155/2020/3701067

Abstract

Most of the traditional cryptanalytic technologies often require a great amount of time, known plaintexts, and memory. This paper proposes a generic cryptanalysis model based on deep learning (DL), where the model tries to find the key of block ciphers from known plaintext-ciphertext pairs. We show the feasibility of the DL-based cryptanalysis by attacking on lightweight block ciphers such as simplified DES, Simon, and Speck. The results show that the DL-based cryptanalysis can successfully recover the key bits when the keyspace is restricted to 64 ASCII characters. The traditional cryptanalysis is generally performed without the keyspace restriction, but only reduced-round variants of Simon and Speck are successfully attacked. Although a text-based key is applied, the proposed DL-based cryptanalysis can successfully break the full rounds of Simon32/64 and Speck32/64. The results indicate that the DL technology can be a useful tool for the cryptanalysis of block ciphers when the keyspace is restricted.

Highlights

Cryptanalysis of block ciphers has persistently received great attention
Because of the bias of the occurrence probability of each key bit in the text key, we need to eliminate the bias characteristics of each key bit. e deep neural networks (DNNs) shows that the key bits, which are quite vulnerable to the attack, are (k2, k5, k8) in the text key and (k1, k5, k8) in the random key. e key bit of k6 is the safest both in the text key and in the random key
The results vary with each simulation with different hyperparameters. at is, the DNN failed to attack the Simon32/64 with a random key

Summary

Introduction

Cryptanalysis of block ciphers has persistently received great attention. In particular, recently, many cryptanalytic techniques have emerged. e cryptanalysis based on the algorithm of algebraic structures can be categorized as follows: a differential cryptanalysis, a linear cryptanalysis, a differential-linear cryptanalysis, a meet-in-the-middle (MITM) attack, and a related-key attack [1, 2]. E cryptanalysis based on the algorithm of algebraic structures can be categorized as follows: a differential cryptanalysis, a linear cryptanalysis, a differential-linear cryptanalysis, a meet-in-the-middle (MITM) attack, and a related-key attack [1, 2]. Differential cryptanalysis, which is the first general cryptanalytic technique, analyses how differences evolve during encryption and how differences of plaintext pairs evolve to differences of the resultant ciphertext pairs [3]. Linear cryptanalysis is a general cryptanalytic technique, where it analyses linear approximations between plaintexts bits, ciphertexts bits, and key bits. In a related-key attack, an attacker can observe the operation of a cipher under several different keys whose values are initially unknown, but where some mathematical relationship connecting the keys is known to the attacker [7]

Objectives

Results

Conclusion