Permutation box

An example of a 64-bit P-Box which spreads the input S-Boxes to as many out S-Boxes as possible.

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.

In block ciphers, the S-boxes and P-Boxes are used to make the relation between the plaintext and the ciphertext difficult to understand (see Shannon's property of confusion). P-boxes are typically classified as compression, expansion, and straight, according as the number of output bits is less than, greater than, or equal to the number of input bits. Only straight P-boxes are invertible.

单词	P Box
释义	P Box 英语百科 Permutation box 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. In block ciphers, the S-boxes and P-Boxes are used to make the relation between the plaintext and the ciphertext difficult to understand (see Shannon's property of confusion). P-boxes are typically classified as compression, expansion, and straight, according as the number of output bits is less than, greater than, or equal to the number of input bits. Only straight P-boxes are invertible.
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P Box

Permutation box