A.To confirm the identity of the receiver 為了確認(rèn)接收者的身份
B.To indicate the encryption algorithm 為了標(biāo)注加密算法
C.To detect any alteration of the message 為了檢測(cè)對(duì)消息的篡改
D.To enable transmission in a digital format 為了便于進(jìn)行數(shù)字格式傳輸