All three types of cryptography schemes have unique function mapping to specific.For example, the synunetric key（71） approach is typically used for theencryption of data providmg（72）, whereas asymmetric key cryptography is maidy used in key（73）and noruepudiation, thereby providing confidentiality and authentication. The hash（74）（noncryptic）, on the other hand, does not provide confidentiality but provides messageintegrity, and cryptographic hash algorithms provide message（75）and identity of peers during transport over insecure channels.
（71） A. Cryptography  B.decode    C.privacy        D .security
（72）A. Conduction   B.confidence  C.confidentiality  D .connection
（73） A. Authentication B.structure    C.encryption    D.exchange
（74） A. Algorithm     B. Secure     C.structure     D.encryption
（75） A. Confidentiality  B. integrity   C.service       D.robustness