Generation of AES-Like S-Boxes by Replacing Affine Matrix

Yousaf

Security and Communication Networks

et al. 2020

Self Cite

Key schedule algorithms play an important role in modern encryption algorithms, and their security is as crucial as the security of the encryption algorithms themselves. Many studies have been performed on the cryptographic strength evaluation of the encryption algorithms; however, strength evaluation of the key schedule algorithms often obtains less attention that can lead towards the possible loophole in the overall encryption process. In this paper, a criterion is proposed to evaluate the cryptographic strength of the key schedule algorithms. This criterion includes different methods of data generation from subkeys and a suitable set of statistical tests. The statistical tests are used to explore the cryptographic properties such as diffusion, confusion, independence, and randomness in the subkeys generated by the key schedule algorithm. The proposed criterion has been applied to some of the key schedule algorithms of different block ciphers. The results confirm that the proposed criterion can effectively differentiate between strong- and weak-key schedule algorithms.

Section: Key Schedule Evaluation Criterionmentioning

confidence: 99%

Cryptographic Strength Evaluation of Key Schedule Algorithms

Yousaf

Security and Communication Networks

et al. 2020

Self Cite

“…In Waqas et al (2015), altered the affine matrix for creation of 46 S-boxes. From a list of 255 affine matrices, 190 matrices were invertible.…”

Section: Related Work Existing Substitution Methodsmentioning

confidence: 99%

A secure key dependent dynamic substitution method for symmetric cryptosystems

Ejaz

Shoukat

Iqbal

et al. 2021

PeerJ Computer Science

The biggest challenge for symmetric cryptosystems is to replace their static substitution with dynamic substitution, because static substitution S-boxes make the symmetric block ciphers more vulnerable to attacks. Previous well-known dynamic key-dependent S-boxes are lacking in dynamicity and do not provide optimal security for symmetric block ciphers. Therefore, this research aims to contribute an effective and secure method for designing key-dependent dynamic S-box with dynamic permutations to make the symmetric block ciphers optimally secure. The proposed S-box method has been experimentally evaluated through several measures such as bit independence criteria, non-linearity, hamming distance, balanced output, strict avalanche criteria including differential and linear approximation probabilities. Moreover, the randomness properties of proposed method have also been evaluated through several standard statistical tests as recommended by the National Institute of Standards and Technology (NIST). Thus, the results show that the proposed method, not only retains effective randomness properties but it also contains, good avalanche effect (up to 62.32%) which is significantly improved than others. Therefore, the proposed substitution method is highly sensitive to the secret key because, only a single bit change in key generates an entirely new S-box with all 256 values at different positions. Thus, the overall evaluation shows that the proposed substitution method is optimally secure and outperforming as compared to the existing S-box techniques. In future, the proposed method can be extended for different key sizes (192–256 bits) or even more.

“…The expression of the affine transformation defined on GF(2) is y = Ax+b, where A is the 8 ´8 invertible matrix and b is a constant of 8 bits. A 1 , A 2 and A 3 are relatively good affine matrices [36,37], and their corresponding affine transformations are equations (9)- (11), respectively. Assuming that A is taken as A 1 and b is taken as 45, the corresponding affine transformations are equation (12).…”

Section: Dynamic High-performance S-boxmentioning

confidence: 99%

Efficient image encryption algorithm based on dynamic high-performance S-box and hyperchaotic system

Tong

Zhang

et al. 2023

Phys. Scr.

With the development of information technology, security, low latency, and instant messaging have become a major demand. To solve this problem, this paper designs a secure and efficient image cipher algorithm. Firstly, a new four-dimensional hyperchaotic system with strong chaotic performance is proposed. Secondly, a dynamic high-performance S-box generation algorithm is proposed based on GF(28) by improving the method of generating S-boxes in AES, selecting suitable irreducible polynomial as well as affine matrix, precomputing the corresponding affine multiplication matrix as well as multiplication inverse matrix. The S-box algebraic expressions generated by this algorithm have 255 terms and are more resistant to algebraic attacks than AES. Finally, based on the four-dimensional hyperchaotic system and dynamic high-performance S-box generation algorithm, the new image cipher algorithm that can encrypt and decrypt images of arbitrary size is proposed. The image cipher algorithm consists of two rounds of interleaved permutation, two rounds of dynamic S-box substitution and cyclic shift permutation with fixed point. Cyclic shift permutation with fixed point and dynamic S-box substitution ensure that the plaintext transformation can be transferred to the entire image. Through testing and analysis and comparison, the algorithm has proven to be a secure and efficient cipher algorithm.