Improved deep learning aided key recovery framework:applications to large-state block ciphers

At the Annual International Cryptology Conference in 2019,Gohr introduced a deep learning based cryptanalysis technique applicable to the reduced-round lightweight block ciphers with a short block of SPECK32/64.One significant challenge left unstudied by Gohr's work is the implementation of key recovery attacks on large-state block ciphers based on deep learning.The purpose of this paper is to present an improved deep learning based framework for recovering keys for large-state block ciphers.First,we propose a key bit sensitivity test(KBST)based on deep learning to divide the key space objectively.Second,we propose a new method for constructing neural distinguisher combinations to improve a deep learning based key recovery framework for large-state block ciphers and demonstrate its rationality and effectiveness from the perspective of cryptanalysis.Under the improved key recovery framework,we train an efficient neural distinguisher combination for each large-state member of SIMON and SPECK and finally carry out a practical key recovery attack on the large-state members of SIMON and SPECK.Furthermore,we propose that the 13-round SIMON64 attack is the most effective approach for practical key recovery to date.Noteworthly,this is the first attempt to propose deep learning based practical key recovery attacks on18-round SIMON128,19-round SIMON128,14-round SIMON96,and 14-round SIMON64.Additionally,we enhance the outcomes of the practical key recovery attack on SPECK large-state members,which amplifies the success rate of the key recovery attack in comparison to existing results.

Split-n-Swap: A New Modification of the Twofish Block Cipher Algorithm

Securing digital data from unauthorized access throughout its entire lifecycle has been always a critical concern.A robust data security system should protect the information assets of any organization against cybercriminal activities.The Twofish algorithm is one of the well-known symmetric key block cipher cryptographic algorithms and has been known for its rapid convergence.But when it comes to security,it is not the preferred cryptographic algorithm to use compared to other algorithms that have shown better security.Many applications and social platforms have adopted other symmetric key block cipher cryptographic algorithms such as the Advanced Encryption Standard(AES)algorithm to construct their main security wall.In this paper,a new modification for the original Twofish algorithm is proposed to strengthen its security and to take advantage of its fast convergence.The new algorithm has been named Split-n-Swap(SnS).Performance analysis of the new modification algorithm has been performed using different measurement metrics.The experimental results show that the complexity of the SnS algorithm exceeds that of the original Twofish algorithm while maintaining reasonable values for encryption and decryption times as well as memory utilization.A detailed analysis is given with the strength and limitation aspects of the proposed algorithm.

KAMAR: A Lightweight Feistel Block Cipher Using Cellular Automata

Wireless Multimedia Sensor Network (WMSN) is an advancement of Wireless Sensor Network (WSN) that encapsulates WSN with multimedia information like image and video. The primary factors considered in the design and deployment of WSN are low power consumption, high speed and memory requirements. Security is indeed a major concern, in any communication system. Consequently, design of compact and high speed WMSN with cryptography algorithm for security, without compromising on sensor node performance is a challenge and this paper proposes a new lightweight symmetric key encryption algorithm based on 1 D cellular automata theory. Simulations are performed using MatLab and synthesized using Xilinx ISE. The proposed approach supports both software and hardware implementation and provides better performance compared to other existing algorithms in terms of number of slices, throughput and other hardware utilization.

Analysis and Design for Unsymmetrical Block Encryption Algorithm

This article explains the imbalance in DES and introduces the operators in IDEA. At last it puts forward a Unsym-metrical Block Encryption Algorithm which is achieved by adding some operators to DES.

Discussion of New Padding Method in DES Encryption

DES is a kind of block cipher and before DES encryption the plain text be divided into the same-size blocks. But sometimes the plain text can’t be divided into the exactly size. So padding step is needed to pad the space of the block. The discussion of the block padding is the emphasis of this paper. A new padding method is given and at the last part of the paper the implementation of DES using new padding method is given.

Quantum key recovery attack on SIMON32/64

The quantum security of lightweight block ciphers is receiving more and more attention.However,the existing quantum attacks on lightweight block ciphers only focused on the quantum exhaustive search,while the quantum attacks combined with classical cryptanalysis methods haven’t been well studied.In this paper,we study quantum key recovery attack on SIMON32/64 using Quantum Amplitude Amplification algorithm in Q1 model.At first,we reanalyze the quantum circuit complexity of quantum exhaustive search on SIMON32/64.We estimate the Clifford gates count more accurately and reduce the T gate count.Also,the T-depth and full depth is reduced due to our minor modifications.Then,using four differentials given by Biryukov in FSE 2014 as our distinguisher,we give our quantum key recovery attack on 19-round SIMON32/64.We treat the two phases of key recovery attack as two QAA instances separately,and the first QAA instance consists of four sub-QAA instances.Then,we design the quantum circuit of these two QAA instances and estimate their corresponding quantum circuit complexity.We conclude that the quantum circuit of our quantum key recovery attack is lower than quantum exhaustive search.Our work firstly studies the quantum dedicated attack on SIMON32/64.And this is the first work to study the complexity of quantum dedicated attacks from the perspective of quantum circuit complexity,which is a more fine-grained analysis of quantum dedicated attacks’complexity.

Collision attack on reduced-round Camellia

Camellia is the final winner of 128-bit block cipher in NESSIE. In this paper, we construct some efficient distinguishers between 4-round Camellia and a random permutation of the blocks space. By using collision-searching techniques, the distinguishers are used to attack on 6, 7, 8 and 9 rounds of Camellia with 128-bit key and 8, 9 and 10 rounds of Camellia with 192/256-bit key. The 128-bit key of 6 rounds Camellia can be recovered with 210 chosen plaintexts and 215 encryptions. The 128-bit key of 7 rounds Camellia can be recovered with 212 chosen plaintexts and 254.5 encryptions. The 128-bit key of 8 rounds Camellia can be recovered with 213 chosen plaintexts and 2112.1 encryptions. The 128-bit key of 9 rounds Camellia can be recovered with 2113.6 chosen plaintexts and 2121 encryptions. The 192/256-bit key of 8 rounds Camellia can be recovered with 213 chosen plaintexts and 2111.1 encryptions. The 192/256-bit key of 9 rounds Camellia can be recovered with 213 chosen plaintexts and 2175.6 encryptions. The 256-bit key of 10 rounds Camellia can be recovered with 214 chosen plaintexts and 2239.9 encryptions.