discussion 300 words with apa citations

In cryptography, a permutation box (or P-box) is a method of bit-shuffling used to permute or transpose bits across S-boxes inputs, retaining diffusion while transposing. P-boxes are typically classified as compression, expansion, and straight, depending on whether the number of output bits is less than, greater than, or equal to the number of input bits. Only straight P-boxes are invertible.

Explain the Importance of the P-Box ?