单项选择题
A.server_key_exchangeB.client_key_exchangeC.change_cipher_specD.finished
A.client_hello与server_helloB.client_key_exchange与server_key_exchangeC.certificate_request与certificateD.hello_request与server_hello
A.握手协议B.记录协议C.修改密文规约协议D.告警协议