Function aes_sbox 

pub const fn aes_sbox(value: u8) -> u8

Independent reference AES S-box via inversion in GF(2^8) and affine map.

The AES S-box is S(x) = A(x^254) ⊕ 0x63, where x^254 is the field inverse of x (and 0 maps to 0) and A is a fixed bit-rotation mix. Computing it from the definition, rather than copying a table, gives the tests an oracle that does not share a source with aes_sbox_kernel.