A向B发送消息P，并使用公钥体制进行数字签名。设E表示公钥，D表示私钥，则 B要保留的证据是(31)。基于数论原理的RSA算法的安全性建立在(32)的基础上。 Kerberos是MIT为校园网设计的身份认证系统，该系统利用智能卡产生(33)密钥，可以防止窃听者捕获认证信息。为了防止会话劫持，Kerberos提供了(34)机制，另外报文中还加入了(35)，用于防止重发攻击(Replay Attack)。

(159)

(158)

(157)

For each blank, choose the best answer from the four choices and write down on the answer sheet.

(71)is a one-way function that takes an arbitrarily long piece of plaintext and from it computes a fixed-length bit string.

(72)is a protocol that most USENET machines now use it to allow news articles to propagate from one machine to another over a reliable connection.

(73)is an approach preferred by cable TV providers. In this solution the fiber terminates at an optoelectrical converter and the final segment is a shared coaxial cable.

(74)is a device used to connect two separate network that use different communication protocol.

(75)is a digital-to-digital polar encoding method in which the signal level is always either positive or negative.

(156)

(153)

(154)

(152)

帧中继网的虚电路建立在()

(151)