olemus
P-teisendus, mis ei muuda bittide arvu
= a P-box that does not change the number of bits

https://image.slidesharecdn.com/modernblockcipher-170817223658/95/modern-block-cipher-17-1024.jpg

ülevaateid
https://en.wikipedia.org/wiki/Permutation_box

https://crypto.stackexchange.com/questions/5905/properties-of-ideal-straight-p-boxes

vt ka
- paisutav P-teisendus
- tihendav P-teisendus