Substitution Box

A lookup table mapping a byte to another byte.

• Aims to have high Encryption Confusion

Table Derivation

Involves taking Modular Inverses in a Finite Field $2^8$ then applying a Affine Transformation Can be expressed as a high degree polynomial

$$f(x)=5x^{fe}+9x^{fd}+f9x^{fb}+25x^{f7}+f4x^{ef}+x^{df}+b5x^{bf}+8f{x}^{7f}+63$$

Apply input values 0x00 to 0xff and the outputs are the table values