Ukunyandla

Kumchazanyandla, Unyandla noma ukunyandla inqubo yokuguqukezela (encoding) ukwaziswa. Lenqubo iphendula ukuloba okuyindabuko kokwaziswa, okwaziwa ngokuthi isiqakaqo esicacile (plaintext), ikuphendule kube isiqakaqo esiguqukezelwe (ciphertext). Ngokwemfuneko, yilabo abagunyaziwe kuphela abangakwazi ukusinyalula (decipher) isiqakaqo esiguqukezelwe sibe isiqakaqo esicacile futhi ukuze bafikelele ekwazisweni okuyindabuko. Ukunyandla ngokwakho akukuvimbeli ukukhubezwa kodwa kuvimbela lowo ofuna ukweqela isiqikili esiqondekayo.

Ngokwezizathu zobuchule, icebo lokunyandla livame ukusebenzisa isihluthulelo sonyandla sobunyozelele (pseudo-random) esiphehlwa umkholezima. Kuyinto engenzeka ukuba kunyandlululwe umyalezo ngaphandle kwesihluthulelo, kodwa kuyicebo lonyandla oluklanywe kahle, kuzodingeka amakhono nezinsiza zomcikizo. Umphiwa ogunyaziwe angawunyandlulula kalula umyalezo ngesihluthulelo asihlinzekwe umsunguli kubaphiwa abagunyaziwe kuphela.

Ngokomlando, izinhlobonhlobo ezingafani zokunyandla ziye zasetshenziswa ukusiza kumchazanyandla. Ubunyoninco bokunyandla bangaphambili babusetshenziswa ekuthumeleni imiyalezo empini. Kusuka lapho, sekuvele ubunyoninco obusha osebusetshenziswa ndawo zonke ekucikizeni kwanamuhla. Icebo lokunyandla lwanamuhla lusebenzisa izicabango zesihluthulelo-somphakathi ngesihluthulelo esifanayo. Ubunyoninco bokunyandla banamuhla buqinisekisa ukuvikeleka ngokuba iziCikizi zanamuhla ziyehluleka ukugegema unyandla.