实验五《网络编程与安全》实验报告
课程:java程序设计
姓名:赵冰雨
学号:20165218
指导教师:娄嘉鹏
实验日期:2018.5.29
实验内容、步骤与体会:
任务一
结对实现中缀表达式转后缀表达式的功能 MyBC.java
结对实现从上面功能中获取的表达式中实现后缀表达式求值的功能,调用MyDC.java
- 中缀转后缀
- 设置一个运算符栈,一个后缀表达式字符串
- 从左到右一次对中缀表达式中的每个字符进行如下处理:
- 若ch是左括号
(
,入栈 - 如果ch是数字,将其后数字添加到后缀表达式字符串之后,并添加空格
- 如果ch是运算符,将栈顶若干优先级高于ch的运算符出栈,添加到后缀表达式字符串之后,再将ch入栈。当
(
运算符在栈中时,它的优先级最低 - 若ch是
)
,则若干运算符全部出栈,直到出栈的是左括号,一对括号匹配
- 若ch是左括号
- 若表达式结束,将栈中运算符全部出栈,添加到后缀表达式字符串之后
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
import java.lang.String;
import org.junit.Test;
public class MyBC{
private static final Map<Character, Integer> basic = new HashMap<Character, Integer>();
static {
basic.put('-', 1);
basic.put('+', 1);
basic.put('*', 2);
basic.put('/', 2);
basic.put('(', 0);
}
/**
* 将 中缀表达式 转化为 后缀表达式
*/
public static String toSuffix(String infix){
List<String> queue = new ArrayList<String>();
List<Character> stack = new ArrayList<Character>();
char[] charArr = infix.trim().toCharArray();
String standard = "*/+-()";
char ch = '&';
int len = 0;
for (int i = 0; i < charArr.length; i++) {
ch = charArr[i];
if(Character.isDigit(ch)) {
len++;
}else if(Character.isLetter(ch)) {
len++;
}else if(ch == '.'){
len++;
}else if(Character.isSpaceChar(ch)) {
if(len > 0) {
queue.add(String.valueOf(Arrays.copyOfRange(charArr, i - len, i)));
len = 0;
}
continue;
}else if(standard.indexOf(ch) != -1) {
if(len > 0) {
queue.add(String.valueOf(Arrays.copyOfRange(charArr, i - len, i)));
len = 0;
}
if(ch == '(') {
stack.add(ch);
continue;
}
if (!stack.isEmpty()) {
int size = stack.size() - 1;
boolean flag = false;
while (size >= 0 && ch == ')' && stack.get(size) != '(') {
queue.add(String.valueOf(stack.remove(size)));
size--;
flag = true;
}
while (size >= 0 && !flag && basic.get(stack.get(size)) >= basic.get(ch)) {
queue.add(String.valueOf(stack.remove(size)));
size--;
}
}
if(ch != ')') {
stack.add(ch);
} else {
stack.remove(stack.size() - 1);
}
}
if(i == charArr.length - 1) {
if(len > 0) {
queue.add(String.valueOf(Arrays.copyOfRange(charArr, i - len+1, i+1)));
}
int size = stack.size() - 1;
while (size >= 0) {
queue.add(String.valueOf(stack.remove(size)));
size--;
}
}
}
return queue.stream().collect(Collectors.joining(" "));
}
}
- 后缀表达式求值
- 设置一个操作数栈,从左向右依次对后缀表达式字符串中的每个字符ch进行处理
- 若ch是数字,先将其后连续若干数字转化为整数,再将该整数入栈;
- 若ch是运算符,出栈两个值进行运算,运算结果再入栈;
- 重复以上步骤,直至后缀表达式结束,栈中最后一个数字就是所求表达式的值
import java.util.StringTokenizer;
import java.util.Stack;
public class MyDC {
/**
* constant for addition symbol
*/
private final char ADD = '+';
/**
* constant for subtraction symbol
*/
private final char SUBTRACT = '-';
/**
* constant for multiplication symbol
*/
private final char MULTIPLY = '*';
/**
* constant for division symbol
*/
private final char DIVIDE = '/';
/**
* the stack
*/
private Stack<Integer> stack;
/**
* Sets up this evalutor by creating a new stack.
*/
public MyDC() {
stack = new Stack<Integer>();
}
public int evaluate(String expr) {
int op1, op2, result = 0;
String token;
StringTokenizer tokenizer = new StringTokenizer(expr);
while (tokenizer.hasMoreTokens()) {
token = tokenizer.nextToken();
if (isOperator(token)) { //如果是运算符,调用isOperator
op2 = (stack.pop()).intValue(); //从栈中弹出操作数2
op1 = (stack.pop()).intValue();//从栈中弹出操作数1
result = evalSingleOp(token.charAt(0), op1, op2);
//根据运算符和两个操作数调用evalSingleOp计算result;
stack.push(new Integer(result)); //计算result入栈;
} else//如果是操作数
stack.push(new Integer(Integer.parseInt(token))); //操作数入栈;
}
return result;
}
private boolean isOperator(String token) {
return (token.equals("+") || token.equals("-") ||
token.equals("*") || token.equals("/"));
}
private int evalSingleOp(char operation, int op1, int op2) {
int result = 0;
switch (operation) {
case ADD:
result = op1 + op2;
break;
case SUBTRACT:
result = op1 - op2;
break;
case MULTIPLY:
result = op1 * op2;
break;
case DIVIDE:
result = op1 / op2;
}
return result;
}
}
任务二
1人负责客户端,一人负责服务器
注意责任归宿,要会通过测试证明自己没有问题
基于Java Socket实现客户端/服务器功能,传输方式用TCP
客户端让用户输入中缀表达式,然后把中缀表达式调用MyBC.java的功能转化为后缀表达式,把后缀表达式通过网络发送给服务器
服务器接收到后缀表达式,调用MyDC.java的功能计算后缀表达式的值,把结果发送给客户端
客户端显示服务器发送过来的结果
- 服务器代码
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
public class Service {
public static void main(String[] args) throws IOException{
Service socketService = new Service();
socketService.oneServer();
}
public void oneServer(){
try{
ServerSocket server=null;
try{
server=new ServerSocket(5218);
System.out.println("服务器启动成功!");
}catch(Exception e) {
System.out.println("没有启动监听!"+e);
}
Socket socket=null;
try{
socket=server.accept();
}catch(Exception e) {
System.out.println("Error."+e);
}
String line,line2;
BufferedReader in=new BufferedReader(new InputStreamReader(socket.getInputStream()));
PrintWriter writer=new PrintWriter(socket.getOutputStream());
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
line2=in.readLine();
System.out.println("客户端:"+line2);
MyDC f = new MyDC();
System.out.printf("%d",f.evaluate(line2));
writer.println(Integer.toString(f.evaluate(line2)));
line=br.readLine();
while(!line.equals("end")){
writer.println(line);
writer.flush();
System.out.println("服务器:"+Integer.toString(f.evaluate(in.readLine())));
System.out.println("客户端:"+in.readLine());
line=br.readLine();
}
writer.close();
in.close();
socket.close();
server.close();
}catch(Exception e) {
System.out.println("Error."+e);
}
}
}
- 客户端代码
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.Socket;
import java.net.URL;
public class Client {
public static void main(String[] args) throws IOException {
try {
//Socket socket = new Socket("172.20.10.6", 5218);
Socket socket = new Socket("172.20.10.6", 5218);
System.out.println("客户端启动成功!");
System.out.println("请输入中缀表达式:");
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
PrintWriter write = new PrintWriter(socket.getOutputStream());
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
String expression;
MyBC bc = new MyBC();
expression = br.readLine();
String input =new String();
input = bc.toSuffix("20-16/4+52-18*2");
//学号是:20165218(20)-(16)/4+(53)-(1)*2
while (!expression.equals("end")) {
write.println(input);
write.println(expression);
write.flush();
System.out.println("转化的后缀表达式为:" + input);
System.out.println("服务器返回值为:" + in.readLine());
expression = br.readLine();
}
write.close();
in.close();
socket.close();
} catch (Exception e) {
System.out.println("无法监听:" + e);
}
}
}
任务三
加密结对编程:1人负责客户端,一人负责服务器
0. 注意责任归宿,要会通过测试证明自己没有问题
- 基于Java Socket实现客户端/服务器功能,传输方式用TCP
- 客户端让用户输入中缀表达式,然后把中缀表达式调用MyBC.java的功能转化为后缀表达式,把后缀表达式用3DES或AES算法加密后通过网络把密文发送给服务器
- 服务器接收到后缀表达式表达式后,进行解密(和客户端协商密钥,可以用数组保存),然后调用MyDC.java的功能计算后缀表达式的值,把结果发送给客户端
- 客户端显示服务器发送过来的结果
- AES算法代码
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;
public class AesEncodeUtil {
//初始向量
public static final String VIPARA = "aabbccddeeffgghh"; //AES 为16bytes. DES 为8bytes
//编码方式
public static final String bm = "UTF-8";
//私钥
private static final String ASE_KEY = "aabbccddeeffgghh"; //AES固定格式为128/192/256 bits.即:16/24/32bytes。DES固定格式为128bits,即8bytes。
/**
* 加密
*
* @param cleartext
* @return
*/
public static String encrypt(String cleartext) {
//加密方式: AES128(CBC/PKCS5Padding) + Base64, 私钥:aabbccddeeffgghh
try {
IvParameterSpec zeroIv = new IvParameterSpec(VIPARA.getBytes());
//两个参数,第一个为私钥字节数组, 第二个为加密方式 AES或者DES
SecretKeySpec key = new SecretKeySpec(ASE_KEY.getBytes(), "AES");
//实例化加密类,参数为加密方式,要写全
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding"); //PKCS5Padding比PKCS7Padding效率高,PKCS7Padding可支持IOS加解密
//初始化,此方法可以采用三种方式,按加密算法要求来添加。(1)无第三个参数(2)第三个参数为SecureRandom random = new SecureRandom();中random对象,随机数。(AES不可采用这种方法)(3)采用此代码中的IVParameterSpec
cipher.init(Cipher.ENCRYPT_MODE, key, zeroIv);
//加密操作,返回加密后的字节数组,然后需要编码。主要编解码方式有Base64, HEX, UUE,7bit等等。此处看服务器需要什么编码方式
byte[] encryptedData = cipher.doFinal(cleartext.getBytes(bm));
return new BASE64Encoder().encode(encryptedData);
} catch (Exception e) {
e.printStackTrace();
return "";
}
}
/**
* 解密
*
* @param encrypted
* @return
*/
public static String decrypt(String encrypted) {
try {
byte[] byteMi = new BASE64Decoder().decodeBuffer(encrypted);
IvParameterSpec zeroIv = new IvParameterSpec(VIPARA.getBytes());
SecretKeySpec key = new SecretKeySpec(
ASE_KEY.getBytes(), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
//与加密时不同MODE:Cipher.DECRYPT_MODE
cipher.init(Cipher.DECRYPT_MODE, key, zeroIv);
byte[] decryptedData = cipher.doFinal(byteMi);
return new String(decryptedData, bm);
} catch (Exception e) {
e.printStackTrace();
return "";
}
}
}
- 服务器代码
import java.awt.*;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
public class ServiceAes {
public static void main(String[] args) throws IOException{
Service socketService = new Service();
socketService.oneServer();
}
public void oneServer(){
try{
ServerSocket server=null;
try{
server=new ServerSocket(5223);
System.out.println("服务器启动成功!");
}catch(Exception e) {
System.out.println("没有启动监听!"+e);
}
Socket socket=null;
try{
socket=server.accept();
}catch(Exception e) {
System.out.println("Error."+e);
}
String line,line2;
BufferedReader in=new BufferedReader(new InputStreamReader(socket.getInputStream()));
PrintWriter writer=new PrintWriter(socket.getOutputStream());
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
line2=in.readLine();
System.out.println("客户端:"+line2);
//创建对象aes,并调用 AesEncodeUtil 类中的解密方法
AesEncodeUtil aes = new AesEncodeUtil();
String line3 = new String();
line3 = aes.decrypt(line2);
//调用 MyDC 类计算值
MyDC f = new MyDC();
System.out.printf("%d",f.evaluate(line3));
writer.println(Integer.toString(f.evaluate(line3)));
line=br.readLine();
while(!line.equals("end")){
writer.println(line);
writer.flush();
System.out.println("客户端:"+in.readLine());
System.out.println("服务器:"+Integer.toString(f.evaluate(in.readLine())));
line=br.readLine();
}
writer.close();
in.close();
socket.close();
server.close();
}catch(Exception e) {
System.out.println("Error."+e);
}
}
}
- 客户端代码
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.Socket;
import java.net.URL;
public class ClientAes {
public static void main(String[] args) throws IOException {
try {
//Socket socket = new Socket("10.1.1.234", 5218);
//Socket socket = new Socket("10.1.1.230", 5223);
Socket socket = new Socket("172.20.10.2", 5223);
System.out.println("客户端启动成功!");
System.out.println("请输入中缀表达式:");
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
PrintWriter write = new PrintWriter(socket.getOutputStream());
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
String expression;
MyBC bc = new MyBC();
expression = br.readLine();
String input =new String();
String input2 = new String();
input = bc.toSuffix("1+(4*2)/2+5+4*3-4");
AesEncodeUtil aes = new AesEncodeUtil();
input2 = aes.encrypt(input);
//创建对象aes,并调用 AesEncodeUtil 类中的加密方法
while (!expression.equals("end")) {
write.println(input2);
write.println(expression);
write.flush();
System.out.println("aes加密的后缀表达式为:" );
System.out.println("服务器返回值为:" + in.readLine());
expression = br.readLine();
}
write.close();
in.close();
socket.close();
} catch (Exception e) {
System.out.println("无法监听:" + e);
}
}
}
任务四
密钥分发结对编程:1人负责客户端,一人负责服务器
0. 注意责任归宿,要会通过测试证明自己没有问题
- 基于Java Socket实现客户端/服务器功能,传输方式用TCP
- 客户端让用户输入中缀表达式,然后把中缀表达式调用MyBC.java的功能转化为后缀表达式,把后缀表达式用3DES或AES算法加密通过网络把密文发送给服务器
- 客户端和服务器用DH算法进行3DES或AES算法的密钥交换
- 服务器接收到后缀表达式表达式后,进行解密,然后调用MyDC.java的功能计算后缀表达式的值,把结果发送给客户端
- 客户端显示服务器发送过来的结果
-
执行Diffie-Hellman算法
- 创建DH公钥和私钥
- 创建共享密钥
-
创建DH公钥和私钥
public class Key_DH{
private static final byte skip1024ModulusBytes[] = {
(byte)0xF4, (byte)0x88, (byte)0xFD, (byte)0x58,
(byte)0x4E, (byte)0x49, (byte)0xDB, (byte)0xCD,
(byte)0x20, (byte)0xB4, (byte)0x9D, (byte)0xE4,
(byte)0x91, (byte)0x07, (byte)0x36, (byte)0x6B,
(byte)0x33, (byte)0x6C, (byte)0x38, (byte)0x0D,
(byte)0x45, (byte)0x1D, (byte)0x0F, (byte)0x7C,
(byte)0x88, (byte)0xB3, (byte)0x1C, (byte)0x7C,
(byte)0x5B, (byte)0x2D, (byte)0x8E, (byte)0xF6,
(byte)0xF3, (byte)0xC9, (byte)0x23, (byte)0xC0,
(byte)0x43, (byte)0xF0, (byte)0xA5, (byte)0x5B,
(byte)0x18, (byte)0x8D, (byte)0x8E, (byte)0xBB,
(byte)0x55, (byte)0x8C, (byte)0xB8, (byte)0x5D,
(byte)0x38, (byte)0xD3, (byte)0x34, (byte)0xFD,
(byte)0x7C, (byte)0x17, (byte)0x57, (byte)0x43,
(byte)0xA3, (byte)0x1D, (byte)0x18, (byte)0x6C,
(byte)0xDE, (byte)0x33, (byte)0x21, (byte)0x2C,
(byte)0xB5, (byte)0x2A, (byte)0xFF, (byte)0x3C,
(byte)0xE1, (byte)0xB1, (byte)0x29, (byte)0x40,
(byte)0x18, (byte)0x11, (byte)0x8D, (byte)0x7C,
(byte)0x84, (byte)0xA7, (byte)0x0A, (byte)0x72,
(byte)0xD6, (byte)0x86, (byte)0xC4, (byte)0x03,
(byte)0x19, (byte)0xC8, (byte)0x07, (byte)0x29,
(byte)0x7A, (byte)0xCA, (byte)0x95, (byte)0x0C,
(byte)0xD9, (byte)0x96, (byte)0x9F, (byte)0xAB,
(byte)0xD0, (byte)0x0A, (byte)0x50, (byte)0x9B,
(byte)0x02, (byte)0x46, (byte)0xD3, (byte)0x08,
(byte)0x3D, (byte)0x66, (byte)0xA4, (byte)0x5D,
(byte)0x41, (byte)0x9F, (byte)0x9C, (byte)0x7C,
(byte)0xBD, (byte)0x89, (byte)0x4B, (byte)0x22,
(byte)0x19, (byte)0x26, (byte)0xBA, (byte)0xAB,
(byte)0xA2, (byte)0x5E, (byte)0xC3, (byte)0x55,
(byte)0xE9, (byte)0x2F, (byte)0x78, (byte)0xC7
};
// The SKIP 1024 bit modulus
private static final BigInteger skip1024Modulus
= new BigInteger(1, skip1024ModulusBytes);
// The base used with the SKIP 1024 bit modulus
private static final BigInteger skip1024Base = BigInteger.valueOf(2);
public static void main(String args[ ]) throws Exception{
DHParameterSpec DHP=
new DHParameterSpec(skip1024Modulus,skip1024Base);
KeyPairGenerator kpg= KeyPairGenerator.getInstance("DH");
kpg.initialize(DHP);
KeyPair kp=kpg.genKeyPair();
PublicKey pbk=kp.getPublic();
PrivateKey prk=kp.getPrivate();
// 保存公钥
FileOutputStream f1=new FileOutputStream(args[0]);
ObjectOutputStream b1=new ObjectOutputStream(f1);
b1.writeObject(pbk);
// 保存私钥
FileOutputStream f2=new FileOutputStream(args[1]);
ObjectOutputStream b2=new ObjectOutputStream(f2);
b2.writeObject(prk);
}
}