A fixed substitution table called an SBox is used to substitute output values with input values, which are usually binary digits or bytes. It functions as a nonlinear transformation that strengthens the cryptographic algorithm's security by adding confusion and complexity to the encryption process.
The Substitute Bytes Transformation, often referred to as SubBytes or the S-Box operation, specifically targets the substitution aspect where it replaces each byte of the block with another according to a predefined rule set.
number of techniques have been presented in the literature, which have attempted to improve the performance of the S-box byte-substitution. This paper proposes a new S-box architecture, defining it as ultra low power, robustly parallel and highly efficient in terms of area. The main purpose of the byte substitution step is to reduce the correlation between the input bytes (plaintext) and the output bytes after all rounds (encrypted text.) Each byte of the state is substituted for a different byte according to a "S-box" (substitution-box). This indicates by which value the algorithm replaces which byte in the blocks. The S-box is always the same as it have some specific mathematics behavior.
As we can see from the illustration, 1 Byte Substitution has many fascinating aspects to explore.
The main purpose of the byte substitution step is to reduce the correlation between the input bytes (plaintext) and the output bytes after all rounds (encrypted text.)
![Substitution byte transformation [19] | Download Scientific Diagram](https://www.researchgate.net/profile/Aqeel-Al-Hillali/publication/338486376/figure/fig1/AS:845419911319552@1578575222251/The-procedure-of-AES-algorithm_Q640.jpg "Substitution byte transformation [19] | Download Scientific Diagram")
