2018-2019-2 20175214 实验五《网络编程与安全》实验报告

时间  2019-12-07
标签 实验 网络编程与安全 报告 栏目 系统网络 繁體版
原文   原文链接

1、实验准备状况概述

  • 结对对象：20175209王梓鸿
  • 以前的结对项目已经完成过四则运算的内容，所以在完成实验时没有彻底使用博客连接中给定的代码，基本采用以前结对项目的代码，而且结对项目中的四则运算还能够实现分数的运算，更加全面。
  • 在完成实验的过程当中须要参考实验三中Java密码学算法中的内容。

2、实验内容及步骤

  • 1.提交1html

    • 实验要求：
    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
上传测试代码运行结果截图和码云连接

    • 实验原理java

      • 咱们习惯使用的计算表达式称做中缀表达式，但计算机在计算时不使用中缀表达式；
      • 由于中缀表达式须要计算机遇到符号后向后扫描一位 若为括号或优先级更高的操做符还须要向后继续扫描；
      • 然后缀表达式严格按照从左到右进行计算的模式 符合计算机运行方式；
      • 所以表达式求值分为两部分：中缀转后缀、后缀表达式求值。

    • 实验代码git

      • 中缀转后缀MyBC.java算法

        • 伪代码
        一、设立空栈用于存放操做符
二、从左到右扫描中缀式，若遇到操做数，直接输出，并以空格做为分隔符；
三、若遇到运算符，则与栈顶元素比较，比栈顶级别高则进栈，不然退出栈顶元素并输出，并以空格做为分隔符，优先级从高到低为')' '/' (÷*) (+-) ；
四、若遇到左括号，进栈；若遇到右括号，则一直退栈输出，直到退到左括号止;
五、当栈变成空时，输出的结果即为后缀表达式。
        • 产品代码
        import java.util.Stack;
public class MyBC {
 String C = new String();
 String End = "";            //存储数字的字符串
 public void ChangeString(String str) {
 C = str;
 }
 public String ChangeOrder() {
Stack store = new Stack();     //建立一个存储字符的栈
for (int i = 0; i < C.length(); i++) {
   char op = C.charAt(i);     //将索引值为i处的字符的值返回
   if (op >= '0' && op <= '9') {
       End = End + op;
   }
   else if (op == '(') {
       store.push(op);
   }
   else if (op == '+' || op == '-' || op == '*' || op == '÷'|| op == '/') {
       End = End + " ";
       if (store.empty()) {
           store.push(op);
       }
       else if (compareValue(op) > compareValue((char) store.peek())) {     //比较运算符优先级
           store.push(op);
       }
       else {
           End = End + String.valueOf(store.pop());
           i--;
       }
   }
   else if (op == ')') {
       while ((char) store.peek() != '(') {
           End = End + " " + String.valueOf(store.pop());
       }
   store.pop();
   }
}
while (!store.empty()) {
   End = End + " " + String.valueOf(store.pop());
}
return End;
 }
 public int compareValue(char chi) {
int number = 0;
switch (chi) {
case '(':
   number = 1;
   break;
case '+':
case '-':
   number = 2;
   break;
case '*':
case '÷':
   number = 3;
   break;
case '/':
   number = 4;
   break;
case ')':
   number = 5;
   break;
default:
   number = 0;
   break;
}
return number;
 }
}

      • 后缀表达式计算MyDC.java编程

        • 伪代码
        一、设置一个空栈用于存储数字元素；
二、从左到右扫描后缀表达式，遇操做数，进栈；
三、若遇运算符，则从栈顶弹出两个操做数，执行对应的运算，并将运算后的结果压栈栈；
四、重复执行直至后缀表达式扫描完毕，弹出栈中的最后一个元素即为表达式的值。
        • 产品代码
        import java.util.StringTokenizer;
import java.util.Stack;
public class MyDC {
 String q;
 Stack stack;
 public MyDC() {
stack = new Stack();
 }
 void set(String question) {   //输入后续排列的字符串
q = question;
 }
 public Rational get() {
Rational op1 = new Rational();
Rational op2 = new Rational();
Rational result = new Rational();
result.setNumerator(0);
StringTokenizer token = new StringTokenizer(q, " ");
String temp;
while (token.hasMoreTokens()) {
   temp = token.nextToken();
   if (Isop(temp) == 1) {     //遇到操做符，弹出栈顶的两个数进行运算
       op2 = (Rational) stack.pop();
       op1 = (Rational) stack.pop();//弹出最上面两个操做数
       result = cal(temp.charAt(0), op1, op2);//根据运算符进行运算
       stack.push(result);//将计算结果压栈
   }
   else {
       Rational num = new Rational();
       num.setNumerator(Integer.parseInt(temp));
       stack.push(num);//操做数入栈
   }
}
return result;
 }
 Rational cal(char op, Rational a, Rational b) {           //对栈顶弹出的两个数进行运算
Rational c = new Rational();
switch (op) {
   case '+':
       c = a.add(b);
       break;
   case '-':
       c = a.sub(b);
       break;
   case '*':
       c = a.muti(b);
       break;
   case '÷':
   case '/':
       if(b.getNumerator()==0) {
           System.out.println("生成的算式计算时出现了分母为0的状况！");
           System.exit(0);
       }
       else {
           c = a.div(b);
           break;
       }
   default:
       System.out.println("Wrong!");
}
return c;
 }
 int Isop(String op) {       //判断是否是运算符
if (op.equals("+") || op.equals("-") || op.equals("*") || op.equals("÷") || op.equals("/")) {
   return 1;
}
else {
   return 0;
}
 }
}
      • 有理数类Rational
        • 用于实现分数运算
        public class Rational {
 int numerator = 1 ;   //分子
 int denominator = 1; //分母
 void setNumerator(int a) {  //设置分子
int c=f(Math.abs(a),denominator);  //计算最大公约数
numerator = a/c;
denominator = denominator/c;
if(numerator<0&&denominator<0) {
   numerator = -numerator;
   denominator = -denominator;
}
 }
 void setDenominator(int b) {  //设置分母
int c=f(numerator,Math.abs(b));  //计算最大公约数
numerator = numerator/c;
denominator = b/c;
if(numerator<0&&denominator<0) {
   numerator = -numerator;
   denominator = -denominator;
}
 }
 int getNumerator() {
return numerator;
 }
 int getDenominator() {
return denominator;
 }
 int f(int a,int b) { //求a和b的最大公约数
if(a==0) {
   return 1;
}
if(a<b) {
   int c=a;
   a=b;
   b=c;
}
int r=a%b;
while(r!=0) {
   a=b;
   b=r;
   r=a%b;
}
return b;
 }
 Rational add(Rational r) {  //加法运算
int a=r.getNumerator();
int b=r.getDenominator();
int newNumerator=numerator*b+denominator*a; //计算出新分子
int newDenominator=denominator*b;           //计算出新分母
Rational result=new Rational();
result.setNumerator(newNumerator);
result.setDenominator(newDenominator);
return result;
 }
 Rational sub(Rational r) {  //减法运算
int a=r.getNumerator();
int b=r.getDenominator();
int newNumerator=numerator*b-denominator*a;
int newDenominator=denominator*b;
Rational result=new Rational();
result.setNumerator(newNumerator);
result.setDenominator(newDenominator);
return result;
 }
 Rational muti(Rational r) { //乘法运算
int a=r.getNumerator();
int b=r.getDenominator();
int newNumerator=numerator*a;
int newDenominator=denominator*b;
Rational result=new Rational();
result.setNumerator(newNumerator);
result.setDenominator(newDenominator);
return result;
 }
 Rational div(Rational r)  { //除法运算
int a=r.getNumerator();
int b=r.getDenominator();
int newNumerator=numerator*b;
int newDenominator=denominator*a;
Rational result=new Rational();
if(a==0) {
   System.out.println("该算式无解");
   result.setNumerator(0);
}
else {
   result.setNumerator(newNumerator);
   result.setDenominator(newDenominator);
}
return result;
 }
}

      • 测试代码Test数组

        import java.util.*;
public class Test {
 public static void main(String[] args) {
String question = "";
String question1 = "";
Scanner scanner = new Scanner(System.in);
System.out.println("请输入题目：");
question = scanner.nextLine();
MyBC change = new MyBC();
change.ChangeString(question);
question1 = change.ChangeOrder();
System.out.println(question1);
MyDC getanswer = new MyDC();
getanswer.set(question1);
Rational answer = getanswer.get();
int a = answer.getNumerator();
int b = answer.getDenominator();
float result = (float)a/b;
System.out.println("结果为（保留两位小数）：");
System.out.println(String.format("%.2f",result));
 }
}

    • 测试结果截图安全

  • 2.提交2服务器

    • 实验要求
    一、基于Java Socket实现客户端/服务器功能，传输方式用TCP
二、客户端让用户输入中缀表达式，而后把中缀表达式调用MyBC.java的功能转化为后缀表达式，把后缀表达式经过网络发送给服务器
三、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
四、客户端显示服务器发送过来的结果
五、上传测试结果截图和码云连接

    • 实验原理网络

      • 获取Client端的IP地址
        • 打开终端，输入ipconfig查看；
        • 在命令行输入IP地址；
        • 调用InetAddress类中的geetByName方法获取输入的IP地址；
      • 建立一个套接字，可使用Socket的构造方法；
        • 如：public Socket(java.lang.String host, int port) 其中，host是IP地址，port是端口号。
      • 调用getInputStream()方法得到一个输入流
      • 调用getOutputStream()方法得到一个输出流
      • 服务器端调用ServerSocket实现套接字
      • 使用accept()方法链接客户端和服务器的套接字
      • 调用getInputStream()方法得到一个输入流
      • 调用getOutputStream()方法得到一个输出流

    • 实验代码socket

      • 客户端Client
      import java.io.*;
import java.net.*;
import java.util.Scanner;
public class Client {
 public static void main(String args[]) {
  Socket mysocket;
  DataInputStream in=null;
  DataOutputStream out=null;
  Scanner scanner = new Scanner(System.in);
  try{
      System.out.print("输入服务器的IP:");
      String IP = scanner.nextLine();
      InetAddress address=InetAddress.getByName(IP);
      mysocket = new Socket(address, 2010);
      in=new DataInputStream(mysocket.getInputStream());
      out=new DataOutputStream(mysocket.getOutputStream());
      System.out.println("请输入中缀表达式：");
      while (scanner.hasNext()) {
          String question = scanner.next();
          MyBC change = new MyBC();
          change.ChangeString(question);
          String question1 = change.ChangeOrder();
          System.out.println("后缀表达式为："+question1);
          out.writeUTF(question1);
          String s=in.readUTF(); //in读取信息，堵塞状态
          System.out.println("客户收到服务器的回答:"+s);
          Thread.sleep(500);
          System.out.println("请输入中缀表达式:");
      }
  }
  catch(Exception e) {
      System.out.println("服务器已断开"+e);
  }
 }
}
      • 服务器Server
      import java.io.*;
import java.net.*;
public class Server {
 public static void main(String[] args) {
  ServerSocket serverForClient = null;
  Socket socketOnServer = null;
  DataOutputStream out = null;
  DataInputStream in = null;
  String question = "";
  try {
      serverForClient = new ServerSocket(2010);
  } catch (IOException e) {
      System.out.println(e);
  }
  System.out.println("等待客户呼叫");
  try {
      socketOnServer = serverForClient.accept();
      out = new DataOutputStream(socketOnServer.getOutputStream());
      in = new DataInputStream(socketOnServer.getInputStream());
      while(true) {
          question = in.readUTF(); // in读取信息，堵塞状态
          System.out.println("服务器收到客户传递的后缀表达式为:" + question);
          MyDC getanswer = new MyDC();
          getanswer.set(question);
          Rational answer = getanswer.get();
          int a = answer.getNumerator();
          int b = answer.getDenominator();
          float result = (float) a / b;
          System.out.println("计算出的结果为"+String.format("%.2f",result));
          out.writeUTF(String.format("%.2f",result));
          Thread.sleep(500);
      }
  } catch (Exception e) {
      System.out.println("客户已断开" + e);
  }
 }
}

    • 测试结果截图

      • 客户端

      • 服务器

  • 3.提交3

    • 实验要求
    一、基于Java Socket实现客户端/服务器功能，传输方式用TCP
二、客户端让用户输入中缀表达式，而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算法加密后经过网络把密文发送给服务器
三、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，能够用数组保存），而后调用MyDC.java的功能计算后缀表达式的值，把结果发送给客户端
四、客户端显示服务器发送过来的结果
五、上传测试结果截图和码云连接

    • 实验原理

      • 本部分主要参考Java密码学算法中“Java对称加密-DES算法”部分；
      • 可是此次和结对伙伴没有经过对象序列化方式写入文件中，而是直接将密钥进行传递。
    • 伪代码
      • 客户端
      一、获取密钥生成器KeyGenerator kg=KeyGenerator.getInstance("DESede")
二、初始化密钥生成器kg.init(168);
三、生成密钥SecretKey k=kg.generateKey( );
四、获取主要编码格式byte[ ] kb=k.getEncoded( );
五、传送密钥长度及密钥内容
六、建立密码器Cipher cp=Cipher.getInstance("DESede");
七、初始化密码器cp.init(Cipher.ENCRYPT_MODE, k);
八、获取等待加密的明文byte ptext[]=s.getBytes("UTF8");
九、执行加密byte []ptext=cp.doFinal(ctext)
      • 服务器
      一、接收密钥长度
二、接收密钥内容
三、建立密码器Cipher cp=Cipher.getInstance("DESede");
四、初始化密码器cp.init(Cipher.DECRYPT_MODE, k);
五、执行解密byte []ptext=cp.doFinal(ctext)

    • 实验代码

      • 客户端Client
      import java.io.*;
import java.net.*;
import javax.crypto.*;
import java.util.Scanner;
public class Client {
 public static void main(String args[]) throws Exception{
  Socket mysocket;
  DataInputStream in=null;
  DataOutputStream out=null;
  Scanner scanner = new Scanner(System.in);
  try {
      System.out.print("输入服务器的IP:");
      String IP = scanner.nextLine();
      InetAddress address=InetAddress.getByName(IP);
      mysocket = new Socket(address, 2010);
      in = new DataInputStream(mysocket.getInputStream());
      out = new DataOutputStream(mysocket.getOutputStream());
      KeyGenerator kg = KeyGenerator.getInstance("DESede");
      kg.init(168);
      SecretKey k = kg.generateKey();
      byte []kb = k.getEncoded();
      out.writeUTF(kb.length+ "");
      System.out.println("产生的密钥为");
      for(int i=0;i<kb.length;i++) {
          System.out.print(kb[i]+ " ");
          out.writeUTF(kb[i] +"");
      }
      System.out.println("\n请输入中缀表达式：");
      while(scanner.hasNext()) {
          String question = scanner.next();
          MyBC change = new MyBC();
          change.ChangeString(question);
          String question1 = change.ChangeOrder();
          System.out.println("后缀表达式为："+question1);
          Cipher cp = Cipher.getInstance("DESede");
          cp.init(Cipher.ENCRYPT_MODE,k);
          byte ptext[] = question1.getBytes("UTF8");
          byte ctext[] = cp.doFinal(ptext);
          out.writeUTF(ctext.length + "");
          for(int i=0;i<ctext.length;i++) {
              out.writeUTF(ctext[i] +"");
          }
          String s=in.readUTF(); //in读取信息，堵塞状态
          System.out.println("客户收到服务器的回答:"+s);
          Thread.sleep(500);
          System.out.println("请输入中缀表达式:");
      }
  }
  catch (IOException e) {
      System.out.println("服务器已断开"+e);
  }
 }
}
      • 服务器Server
      import java.io.*;
import java.net.*;
import javax.crypto.*;
import javax.crypto.spec.*;
public class Server {
 public static void main(String[] args) throws Exception{
  ServerSocket serverForClient = null;
  Socket socketOnServer = null;
  DataOutputStream out = null;
  DataInputStream in = null;
  try {
      serverForClient = new ServerSocket(2010);
  } catch (IOException e) {
  System.out.println(e);
  }
  System.out.println("等待客户呼叫");
  try {
      socketOnServer = serverForClient.accept();
      out = new DataOutputStream(socketOnServer.getOutputStream());
      in = new DataInputStream(socketOnServer.getInputStream());
      String keylength = in.readUTF();
      byte []kb = new byte[Integer.parseInt(keylength)];
      System.out.println("收到的密钥为：");
      for(int i = 0;i<Integer.parseInt(keylength);i++) {
          String str = in.readUTF();
          kb[i] = Byte.parseByte(str);
          System.out.print(kb[i] + " ");
      }
      while(true) {
          SecretKeySpec k = new SecretKeySpec(kb, "DESede");
          Cipher cp = Cipher.getInstance("DESede");
          cp.init(Cipher.DECRYPT_MODE, k);
          String clength = in.readUTF();
          byte ctext[] = new byte[Integer.parseInt(clength)];
          for (int i = 0;i<Integer.parseInt(clength);i++) {
              String temp = in.readUTF();
              ctext[i] = Byte.parseByte(temp);
          }
          byte[] ptext = cp.doFinal(ctext);
          String question = new String(ptext,"UTF8");
          System.out.print("\n后缀表达式为："+ question);
          MyDC getanswer = new MyDC();
          getanswer.set(question);
          Rational answer = getanswer.get();
          int a = answer.getNumerator();
          int b = answer.getDenominator();
          float result = (float) a / b;
          System.out.println("\n计算出的结果为"+String.format("%.2f",result));
          out.writeUTF(String.format("%.2f",result));
          Thread.sleep(500);
      }
  } catch (IOException e) {
      System.out.println("客户已断开" + e);
  }
 }
}

    • 测试结果截图

      • 客户端

      • 服务器

  • 4.提交4

    • 实验要求
    一、基于Java Socket实现客户端/服务器功能，传输方式用TCP
二、客户端让用户输入中缀表达式，而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算法加密经过网络把密文发送给服务器
三、客户端和服务器用DH算法进行3DES或AES算法的密钥交换
四、服务器接收到后缀表达式表达式后，进行解密，而后调用MyDC.java的功能计算后缀表达式的值，把结果发送给客户端
五、客户端显示服务器发送过来的结果
六、上传测试结果截图和码云连接

    • 实验原理

      • 本部分主要参考Java密码学算法中“使用密钥协定建立共享密钥”部分
      • 对博客中的代码进行了部分更改以下：
        • Key_DH和KeyAgree主类的参数改成由客户端和服务器传递，并修改方法名
          • public static void DH(String str1,String str2) throws Exception
          • public static void Agree(String str1,String str2)
        • 客户端和服务器分别产生本身的公钥和私钥，并用过字节数组的形式分别向另外一方传递本身的公钥；
        • 客户端和服务器接受对方的公钥后利用本身的私钥建立共享密钥
        • 建立密钥协定对象KeyAgreement ka=KeyAgreement.getInstance("DH");
        • 初始化密钥协定对象ka.init(prk);
        • 执行密钥协定ka.doPhase(pbk,true);
        • 生成共享信息byte[ ] sb=ka.generateSecret();
        • 从文件中读取信息并给出共享密钥

    • 实验代码

      • 客户端Client
      import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.io.*;
import java.security.*;
import java.util.Scanner;
import java.net.*;
public class Client {
 public static void main(String[] args) {
  Socket mysocket;
  DataInputStream in=null;
  DataOutputStream out=null;
  Scanner scanner = new Scanner(System.in);
  try {
      System.out.print("输入服务器的IP:");
      String IP = scanner.nextLine();
      InetAddress address=InetAddress.getByName(IP);
      mysocket = new Socket(address, 2010);
      in = new DataInputStream(mysocket.getInputStream());
      out = new DataOutputStream(mysocket.getOutputStream());
      Key_DH.DH("Lpub.dat","Lpri.dat");
      FileInputStream my = new FileInputStream("Lpub.dat");
      ObjectInputStream mypub = new ObjectInputStream(my);
      Key kp = (Key) mypub.readObject();
      ByteArrayOutputStream DH = new ByteArrayOutputStream();
      ObjectOutputStream myDH = new ObjectOutputStream(DH);
      myDH.writeObject(kp);
      byte []pub = DH.toByteArray();
      out.writeUTF(pub.length+"");
      for(int i=0;i<pub.length;i++) {
          out.writeUTF(pub[i]+ "");
      }
      Thread.sleep(1000);
      int length = Integer.parseInt(in.readUTF());
      byte cpub[] = new byte[length];
      for(int i=0;i<length;i++) {
          String temp = in.readUTF();
          cpub[i] = Byte.parseByte(temp);
      }
      ByteArrayInputStream ckey1 = new ByteArrayInputStream(cpub);
      ObjectInputStream ckey = new ObjectInputStream(ckey1);
      Key k = (Key) ckey.readObject();
      FileOutputStream f2 = new FileOutputStream("W1pub.dat");
      ObjectOutputStream b2 = new ObjectOutputStream(f2);
      b2.writeObject(k);
      KeyAgree.Agree("W1pub.dat","Lpri.dat");
      FileInputStream f = new FileInputStream("sb.dat");
      byte[] keysb = new byte[24];
      f.read(keysb);
      System.out.println("公共密钥为：");
      for (int i = 0;i<24;i++) {
          System.out.print(keysb[i]+" ");
      }
      System.out.println("\n请输入中缀表达式：");
      while(scanner.hasNext()) {
          String question = scanner.next();
          MyBC change = new MyBC();
          change.ChangeString(question);
          String question1 = change.ChangeOrder();
          System.out.println("后缀表达式为：" + question1);
          SecretKeySpec k1 = new SecretKeySpec(keysb, "DESede");
          Cipher cp = Cipher.getInstance("DESede");
          cp.init(Cipher.ENCRYPT_MODE, k1);
          byte ptext[] = question1.getBytes("UTF8");
          byte ctext[] = cp.doFinal(ptext);
          System.out.println("加密后的后缀表达式为：");
          for (int i = 0; i < ctext.length; i++) {
              System.out.print(ctext[i] + " ");
          }
          out.writeUTF(ctext.length + "");
          for (int i = 0; i < ctext.length; i++) {
              out.writeUTF(ctext[i] + "");
          }
          String s=in.readUTF(); //in读取信息，堵塞状态
          System.out.println("\n客户收到服务器的回答:"+s);
          Thread.sleep(500);
          System.out.println("请输入中缀表达式:");
      }
  }
  catch (Exception e) {
      System.out.println(e);
  }
 }
}
      • 服务器Server
      import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.security.*;
public class Server {
 public static void main(String[] args) throws Exception {
  ServerSocket serverForClient = null;
  Socket socketOnServer = null;
  DataOutputStream out = null;
  DataInputStream in = null;
  try {
      serverForClient = new ServerSocket(2010);
  } catch (IOException e) {
      System.out.println(e);
  }
  System.out.println("等待客户呼叫");
  try {
      socketOnServer = serverForClient.accept();
      out = new DataOutputStream(socketOnServer.getOutputStream());
      in = new DataInputStream(socketOnServer.getInputStream());
      Key_DH.DH("Wpub.dat","Wpri.dat");
      int length = Integer.parseInt(in.readUTF());
      byte cpub[] = new byte[length];
      for(int i=0;i<length;i++) {
          String temp = in.readUTF();
          cpub[i] = Byte.parseByte(temp);
      }
      ByteArrayInputStream ckey1 = new ByteArrayInputStream(cpub);
      ObjectInputStream ckey = new ObjectInputStream(ckey1);
      Key k1 = (Key) ckey.readObject();
      FileOutputStream f2 = new FileOutputStream("Lpub.dat");
      ObjectOutputStream b2 = new ObjectOutputStream(f2);
      b2.writeObject(k1);
      FileInputStream my = new FileInputStream("Wpub.dat");
      ObjectInputStream mypub = new ObjectInputStream(my);
      Key kp = (Key) mypub.readObject();
      ByteArrayOutputStream DH = new ByteArrayOutputStream();
      ObjectOutputStream myDH = new ObjectOutputStream(DH);
      myDH.writeObject(kp);
      byte []pub = DH.toByteArray();
      out.writeUTF(pub.length+"");
      for(int i=0;i<pub.length;i++) {
          out.writeUTF(pub[i]+ "");
      }
      KeyAgree.Agree("Lpub.dat","Wpri.dat");
      FileInputStream f = new FileInputStream("sb.dat");
      byte[] keysb = new byte[24];
      f.read(keysb);
      System.out.println("公共密钥为：");
      for (int i = 0;i<24;i++) {
          System.out.print(keysb[i]+" ");
      }
      while(true) {
          SecretKeySpec k = new SecretKeySpec(keysb, "DESede");
          Cipher cp = Cipher.getInstance("DESede");
          cp.init(Cipher.DECRYPT_MODE, k);
          String clength = in.readUTF();
          byte ctext[] = new byte[Integer.parseInt(clength)];
          for (int i = 0; i < Integer.parseInt(clength); i++) {
              String temp = in.readUTF();
              ctext[i] = Byte.parseByte(temp);
          }
          byte[] ptext = cp.doFinal(ctext);
          String question = new String(ptext, "UTF8");
          System.out.print("\n解密后的后缀表达式为：" + question);
          MyDC getanswer = new MyDC();
          getanswer.set(question);
          Rational answer = getanswer.get();
          int a = answer.getNumerator();
          int b = answer.getDenominator();
          float result = (float) a / b;
          System.out.println("\n计算出的结果为"+String.format("%.2f",result));
          out.writeUTF(String.format("%.2f",result));
          Thread.sleep(500);
      }
  }
  catch(Exception e) {
      System.out.println("客户已断开" + e);
  }
 }
}

    • 测试结果截图

      • 客户端

      • 服务器

  • 5.任务五

    • 实验要求
    一、基于Java Socket实现客户端/服务器功能，传输方式用TCP
二、客户端让用户输入中缀表达式，而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算法加密经过网络把密文和明文的MD5値发送给服务器
三、客户端和服务器用DH算法进行3DES或AES算法的密钥交换
四、服务器接收到后缀表达式表达式后，进行解密，解密后计算明文的MD5值，和客户端传来的MD5进行比较，一致则调用MyDC.java的功能计算后缀表达式的值，把结果发送给客户端
五、客户端显示服务器发送过来的结果
六、上传测试结果截图和码云连接

    • 实验原理

      • 本部分主要参考Java密码学算法中“Java摘要算法- MD5”部分；
      • 主要在任务四基础上进行操做。

    • 实验代码

      • 客户端Client
      import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.io.*;
import java.net.Socket;
import java.security.*;
import java.util.Scanner;
import java.net.*;
public class Client {
 public static void main(String[] args) {
  Socket mysocket;
  DataInputStream in=null;
  DataOutputStream out=null;
  Scanner scanner = new Scanner(System.in);
  try {
      System.out.print("输入服务器的IP:");
      String IP = scanner.nextLine();
      InetAddress address=InetAddress.getByName(IP);
      mysocket = new Socket(address, 2010);
      in = new DataInputStream(mysocket.getInputStream());
      out = new DataOutputStream(mysocket.getOutputStream());
      Key_DH.DH("Lpub.dat","Lpri.dat");
      FileInputStream my = new FileInputStream("Lpub.dat");
      ObjectInputStream mypub = new ObjectInputStream(my);
      Key kp = (Key) mypub.readObject();
      ByteArrayOutputStream DH = new ByteArrayOutputStream();
      ObjectOutputStream myDH = new ObjectOutputStream(DH);
      myDH.writeObject(kp);
      byte []pub = DH.toByteArray();
      out.writeUTF(pub.length+"");
      for(int i=0;i<pub.length;i++) {
          out.writeUTF(pub[i]+ "");
      }
      Thread.sleep(1000);
      int length = Integer.parseInt(in.readUTF());
      byte cpub[] = new byte[length];
      for(int i=0;i<length;i++) {
          String temp = in.readUTF();
          cpub[i] = Byte.parseByte(temp);
      }
      ByteArrayInputStream ckey1 = new ByteArrayInputStream(cpub);
      ObjectInputStream ckey = new ObjectInputStream(ckey1);
      Key k = (Key) ckey.readObject();
      FileOutputStream f2 = new FileOutputStream("W1pub.dat");
      ObjectOutputStream b2 = new ObjectOutputStream(f2);
      b2.writeObject(k);
      KeyAgree.Agree("W1pub.dat","Lpri.dat");
      FileInputStream f = new FileInputStream("sb.dat");
      byte[] keysb = new byte[24];
      f.read(keysb);
      System.out.println("公共密钥为：");
      for (int i = 0;i<24;i++) {
          System.out.print(keysb[i]+" ");
      }
      System.out.println("\n请输入中缀表达式：");
      while(scanner.hasNext()) {
          String question = scanner.next();
          MyBC change = new MyBC();
          change.ChangeString(question);
          String question1 = change.ChangeOrder();
          System.out.println("后缀表达式为：" + question1);
          String mtoMD5 = DigestPass.MD5(question1);
          System.out.println("明文的MD5值为："+mtoMD5);
          out.writeUTF(mtoMD5);
          SecretKeySpec k1 = new SecretKeySpec(keysb, "DESede");
          Cipher cp = Cipher.getInstance("DESede");
          cp.init(Cipher.ENCRYPT_MODE, k1);
          byte ptext[] = question1.getBytes("UTF8");
          byte ctext[] = cp.doFinal(ptext);
          System.out.println("加密后的后缀表达式为：");
          for (int i = 0; i < ctext.length; i++) {
              System.out.print(ctext[i] + " ");
          }
          out.writeUTF(ctext.length + "");
          for (int i = 0; i < ctext.length; i++) {
              out.writeUTF(ctext[i] + "");
          }
          String s=in.readUTF(); //in读取信息，堵塞状态
          System.out.println("\n客户收到服务器的回答:"+s);
          Thread.sleep(500);
          System.out.println("请输入中缀表达式:");
      }
  }
  catch (Exception e) {
      System.out.println(e);
  }
 }
}
      • 服务器Server
      import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.security.*;
public class Server {
 public static void main(String[] args) throws Exception {
  ServerSocket serverForClient = null;
  Socket socketOnServer = null;
  DataOutputStream out = null;
  DataInputStream in = null;
  try {
      serverForClient = new ServerSocket(2010);
  } catch (IOException e) {
      System.out.println(e);
  }
  System.out.println("等待客户呼叫");
  try {
      socketOnServer = serverForClient.accept();
      out = new DataOutputStream(socketOnServer.getOutputStream());
      in = new DataInputStream(socketOnServer.getInputStream());
      Key_DH.DH("Wpub.dat","Wpri.dat");
      int length = Integer.parseInt(in.readUTF());
      byte cpub[] = new byte[length];
      for(int i=0;i<length;i++) {
          String temp = in.readUTF();
          cpub[i] = Byte.parseByte(temp);
      }
      ByteArrayInputStream ckey1 = new ByteArrayInputStream(cpub);
      ObjectInputStream ckey = new ObjectInputStream(ckey1);
      Key k1 = (Key) ckey.readObject();
      FileOutputStream f2 = new FileOutputStream("L1pub.dat");
      ObjectOutputStream b2 = new ObjectOutputStream(f2);
      b2.writeObject(k1);
      FileInputStream my = new FileInputStream("Wpub.dat");
      ObjectInputStream mypub = new ObjectInputStream(my);
      Key kp = (Key) mypub.readObject();
      ByteArrayOutputStream DH = new ByteArrayOutputStream();
      ObjectOutputStream myDH = new ObjectOutputStream(DH);
      myDH.writeObject(kp);
      byte []pub = DH.toByteArray();
      out.writeUTF(pub.length+"");
      for(int i=0;i<pub.length;i++) {
          out.writeUTF(pub[i]+ "");
      }
      KeyAgree.Agree("L1pub.dat","Wpri.dat");
      FileInputStream f = new FileInputStream("sb.dat");
      byte[] keysb = new byte[24];
      f.read(keysb);
      System.out.println("公共密钥为：");
      for (int i = 0;i<24;i++) {
          System.out.print(keysb[i]+" ");
      }
      while(true) {
          String c = in.readUTF();
          SecretKeySpec k = new SecretKeySpec(keysb, "DESede");
          Cipher cp = Cipher.getInstance("DESede");
          cp.init(Cipher.DECRYPT_MODE, k);
          String clength = in.readUTF();
          byte ctext[] = new byte[Integer.parseInt(clength)];
          for (int i = 0; i < Integer.parseInt(clength); i++) {
              String temp = in.readUTF();
              ctext[i] = Byte.parseByte(temp);
          }
          byte[] ptext = cp.doFinal(ctext);
          String question = new String(ptext, "UTF8");
          System.out.println("\n解密后的后缀表达式为：" + question);
          String mtoMD5 = DigestPass.MD5(question);
          System.out.println("MD5的值为"+ mtoMD5);
          if(mtoMD5.equals(c)) {
              System.out.println("传递的MD5值和解密的后缀表达式的MD5值相同，能够解密！");
              MyDC getanswer = new MyDC();
              getanswer.set(question);
              Rational answer = getanswer.get();
              int a = answer.getNumerator();
              int b = answer.getDenominator();
              float result = (float) a / b;
              System.out.println("计算出的结果为"+String.format("%.2f",result));
              out.writeUTF(String.format("%.2f",result));
          }
          else {
              System.out.println("密文有误，不能解密！");
          }
          Thread.sleep(500);
      }
  }
  catch(Exception e) {
      System.out.println("客户已断开" + e);
  }
 }
}

    • 测试结果截图

      • 客户端

      • 服务器

3、代码托管

4、实验心得体会

本次实验综合了教材第十三章和Java密码学的相关内容，在和伙伴的讨论中，对于java的网络和安全方面的编程有了更好地掌握。

5、参考资料

相关文章
相关标签/搜索
每日一句
    每一个你不满意的现在，都有一个你没有努力的曾经。
本站公众号
   欢迎关注本站公众号,获取更多信息
联系我们 最近搜索 最新文章 沪ICP备13005482号-10 MyBatis教程 SQL 教程 MySQL教程 Java 教程 Thymeleaf 教程 Hibernate教程 Spring教程 Redis教程