Proposal of dynamic algorithms combining a substitution layer and a key addition layer for block ciphers using SHA3-256
Trần Thị Lượng · Research and Development on Information and Communication Technology · 2025
In recent years, one research direction that has garnered significant attention from scientists is enhancing the security of SPN block ciphers against strong cryptanalysis attacks through dynamic methods. Researchers have focused on proposing dynamic implementations of substitution layers, diffusion layers, and key addition layers, as well as combinations of these layers. These proposals are often based on mathematical foundations such as chaotic mappings, DNA techniques, affine transformations, or specially structured MDS matrices, among others. However, none of these studies have utilized the mathematical foundation of hash functions or combined substitution and key addition layers, nor have they leveraged the results of these layers as dynamic parameters for other layers. Therefore, in this study, we propose two dynamic algorithms that combine the key addition layer and substitution layer using the cryptographic hash function SHA3-256. Additionally, the dynamic method for the substitution layer is implemented using parameters derived from the key addition layer. We use the proposed dynamic algorithms to dynamically modify the AES block cipher, while evaluating the security and randomness standards of the dynamic AES block cipher. With the two proposed dynamic algorithms, not only is there no increase in the expanded key size, but the security of the modified dynamic AES algorithm can also be significantly enhanced to 2^176.