The NASZ algorithm is cipher used to protect Polish state secrets. The cipher itself is secret and its implementations are only available in devices produced for govermental or military use (like CompCrypt by COMP S.A.). The cipher’s name is an acronym for Narodowy Algorytm Szyfrujący (National Encryption Algorithm), with presumably intended pun as nasz means “ours” in Polish.
NASZ is actually based on 3DES with additional transformations. Their construction is secret. Almost for sure it’s not modified initial and final permutations, maybe that’s whitening. Purpose of those transformations isn’t clear, maybe they were used to make the existing harware implementations of 3DES useless.
There are a few versions (modes?) of NASZ, used for different secrecy levels: NASZ-P is allowed to protect “Secret”, NASZ-T - “Top Secret”. As a digression, CompCrypt devices use 3DES in ECB mode to protect information with “Restricted” secrecy clause. Those devices use specialised MCY74C609 chip designed by Institute of Electron Technology in cooperation with TechLab 2000 company (both from Warsaw).