▁a ▁human ▁crypt ograph er ▁to ▁encrypt ▁plain text s ▁under ▁numerous ▁secret ▁keys ▁related ▁in ▁some ▁way . ▁ ▁K AS UM I ▁K AS UM I ▁is ▁an ▁eight ▁round , ▁ 6 4 - bit ▁block ▁ci pher ▁with ▁a ▁ 1 2 8 - bit ▁key . ▁It ▁is ▁based ▁upon ▁M IST Y 1 , ▁and ▁was ▁designed ▁to ▁form ▁the ▁basis ▁of ▁the ▁ 3 G ▁confident ial ity ▁and ▁integrity ▁algorithms . ▁ ▁Mark ▁Bl unden ▁and ▁Ad rian ▁Esc ott ▁described ▁differential ▁related ▁key ▁attacks ▁on ▁five ▁and ▁six ▁r ounds ▁of ▁K AS UM I . ▁D iffer ential ▁attacks ▁were ▁introduced ▁by ▁Bi ham ▁and ▁Sh am ir . ▁Rel ated ▁key ▁attacks ▁were ▁first ▁introduced ▁by ▁Bi ham . ▁D iffer ential ▁related ▁key ▁attacks ▁are ▁discussed ▁in ▁K else y ▁et ▁al . ▁ ▁W EP ▁An ▁important ▁example ▁of ▁a ▁crypt ographic ▁protocol ▁that ▁failed ▁because ▁of ▁a ▁related - key ▁attack ▁is ▁W ired ▁Equ ivalent ▁Priv acy ▁( WE P ) ▁used ▁in ▁Wi - Fi ▁wireless ▁networks . ▁ ▁Each ▁client ▁Wi - Fi ▁network ▁adapter ▁and ▁wireless ▁access ▁point ▁in ▁a ▁W EP - protected ▁network ▁shares ▁the ▁same ▁W EP ▁key . ▁Enc ryption ▁uses ▁the ▁RC 4 ▁algorithm , ▁a ▁stream ▁ci pher . ▁It ▁is ▁essential ▁that ▁the ▁same ▁key ▁never ▁be ▁used ▁twice ▁with ▁a ▁stream ▁ci pher . ▁To ▁prevent ▁this ▁from ▁happening , ▁W EP ▁includes ▁a ▁ 2 4