ItiswellknownthatthealgebraicexpressionofASSS-boxisverysimpleandonly9termsareinvolved.Hence,AESsecurityissuspectedalthoughthereisnovulnerabilityonitsofar.ToeliminatetheweaknessofextremelysmalltermsinthealgebraicexpressionofAESS-box,oneimprovedAESS-boxisproposed,whichpreservesthealgebraicdegreeinvariablebutsignificantlyincreasesthenumberofitsalgebraicexpressiontermsfrom9to255.Atthesametime,Booleanfunctionhasgoodcharactersinbalanceandstrictavalanchecriterion(SAC),etc.Finally,itisprovedthattheimprovedAESS-boxschemeissecuregainstthepowerfulknowndifferentialandlinearcryptanalysis.
