# DH 密钥交换算法

Diffie-Hellman-Merkle(DH) 算法是最早的公钥交换算法之一。DH 算法在公共网络中建立了一个可靠的通信通道。

# 网络安全 第三章 Internet协议的安全性

## 3.1 Internet 协议概述

TCP / IP 协议族

• 网络接口层
• TCP / IP 模型的最底层
• 网际层
• IP、ARP
• 传输层
• TCP、UDP
• 应用层
• HTTP、SMTP、POP3、FTP

# 信息系统安全 第一章 信息系统安全概述

## 计算机信息系统安全问题

• 政治
• 1999 - 2001，我国政府网站遭受四次大规模黑客攻击
• 经济
• CIH 病毒、冲击波病毒、熊猫烧香病毒等造成的经济损失
• 社会稳定
• 虚假、有害信息对社会秩序的危害
• 军事
• 以信息战为主的作战形态，海湾战争、科索沃战争等

# POJ3684 Physics Experiment

## Description

Simon is doing a physics experiment with N identical balls with the same radius of R centimeters. Before the experiment, all N balls are fastened within a vertical tube one by one and the lowest point of the lowest ball is H meters above the ground. At beginning of the experiment, (at second 0), the first ball is released and falls down due to the gravity. After that, the balls are released one by one in every second until all balls have been released. When a ball hits the ground, it will bounce back with the same speed as it hits the ground. When two balls hit each other, they with exchange their velocities (both speed and direction).

# POJ3279 Fliptile

## Description

Farmer John knows that an intellectually satisfied cow is a happy cow who will give more milk. He has arranged a brainy activity for cows in which they manipulate an M × N grid (1 ≤ M ≤ 15; 1 ≤ N ≤ 15) of square tiles, each of which is colored black on one side and white on the other side.