Which of the following statements about MD5 Routing Updates authentication is valid？ （）

A.The MD5 algorithm inputs the routing updates of arbitrary length and outputs a 128-bit hash

B.The MD5 algorithm inputs the routing updates of every 64bit length and outputs an 8-bit hash

C.Multiple keys are supported

D.Routing updates packets are delivered in encrypted messages

E.Shared secret keys are delivered in encrypted messages