Allthreetypesofcryptographyschemeshaveuniquefunctionmappingtospecific．Forexample,thesymmetrickeyapproach(71)istypicallyusedfortheencryptionofdataproviding(72),whereasasymmetrickeycryptographyismaidyusedinkey(73)andnonrepudiation,therebyprovidingconfidentialityandauthentication．Thehash(74)(noncryptic),ontheotherhand,doesnotprovideconfidentialitybutprovidesmessageintegrity,andcryptographichashalgorithmsprovidemessage(75)andidentityofpeersduringtransportoverinsecurechannels．
A.Authentication
B.structure
C.encryption
D.exchange
正确答案是D