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