For security purposes data sources are allowed to register to NOS;theregistrationgivesvariousadvantages,since
it allowsNOStohaveacompleteknowledgeofthesource
itselfandtoestablishanencryptionschemealongwiththe
properkeysandidentifierstobeused.Someregistered
sourcesmayuseneitherauthenticationcredentialsnor
encryption.NOSacceptsdataalsofromanonymoussour-
ces;alsointhiscaseasecurityevaluationhastobeper-
formed.The SecurityAnalyzer mustbeabletoaccesstothe
Sources storageunitsince,inordertoanalyzethereceived
data,itmayneedinformationregardingthesources