网络编程及安全

实验目的与要求

1．掌握Java网络编程的方法

2．掌握Java安全编程的方法

3．实现TCP加解密

实验内容与步骤

1    编写网络通信程序(基于TCP) 

2    对通信内容使用对称加密算法进行加密

3    使用非对称算法分发对称加密中使用的密钥

客户端：

import java.net.*;

import java.security.*;

import javax.crypto.*;

import java.io.*;

public class ComputeTCPClient {

    public static void main(String srgs[]) {

          try {

           //创建连接特定服务器的指定端口的Socket对象

            Socket socket = new Socket("0.0.0.0", 4421);

            //获得从服务器端来的网络输入流

            BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));

            //获得从客户端向服务器端输出数据的网络输出流

            PrintWriter out=new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())),true);

                      

            FileReader f1=new FileReader("e:/muhw.txt");

            BufferedReader stdin=new BufferedReader(f1);

            String str=stdin.readLine();

            String s=new String(str);

       

        FileInputStream f=new FileInputStream("key1.dat");

        ObjectInputStream b=new ObjectInputStream(f);

        Key k=(Key)b.readObject( );

       

        Cipher cp=Cipher.getInstance("DESede");

        cp.init(Cipher.ENCRYPT_MODE, k);

       

        byte ptext[]=s.getBytes("UTF8");

        byte ctext[]=cp.doFinal(ptext);

               

        FileOutputStream f2=new FileOutputStream("SEnc.dat");

        f2.write(ctext);

        FileReader f3=new FileReader("SEnc.dat");

            BufferedReader stdin3=new BufferedReader(f3);

            String str3=stdin3.readLine();

            out.println(str3);  //通过网络传送密文到服务器 

           String str1=in.readLine();//从网络输入流读取结果

           System.out.println( "服务器接收到的结果为："+str1); //输出服务器返回的结果

          

          

                      

       }

        catch (Exception e) {

            System.out.println(e);

        }

        finally{

            //stdin.close();

            //in.close();

            //out.close();

            //socket.close();          

        }

     }

}

服务器：

import java.net.*;

import java.security.*;

import javax.crypto.*;

import java.io.*;

public class ComputeTCPClient {

    public static void main(String srgs[]) {

          try {

           //创建连接特定服务器的指定端口的Socket对象

            Socket socket = new Socket("0.0.0.0", 4421);

            //获得从服务器端来的网络输入流

            BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));

            //获得从客户端向服务器端输出数据的网络输出流

            PrintWriter out=new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())),true);

                      

            FileReader f1=new FileReader("e:/muhw.txt");

            BufferedReader stdin=new BufferedReader(f1);

            String str=stdin.readLine();

            String s=new String(str);

       

        FileInputStream f=new FileInputStream("key1.dat");

        ObjectInputStream b=new ObjectInputStream(f);

        Key k=(Key)b.readObject( );

       

        Cipher cp=Cipher.getInstance("DESede");

        cp.init(Cipher.ENCRYPT_MODE, k);

       

        byte ptext[]=s.getBytes("UTF8");

        byte ctext[]=cp.doFinal(ptext);

               

        FileOutputStream f2=new FileOutputStream("SEnc.dat");

        f2.write(ctext);

        FileReader f3=new FileReader("SEnc.dat");

            BufferedReader stdin3=new BufferedReader(f3);

            String str3=stdin3.readLine();

            out.println(str3);  //通过网络传送密文到服务器 

           String str1=in.readLine();//从网络输入流读取结果

           System.out.println( "服务器接收到的结果为："+str1); //输出服务器返回的结果

          

          

                      

       }

        catch (Exception e) {

            System.out.println(e);

        }

        finally{

            //stdin.close();

            //in.close();

            //out.close();

            //socket.close();          

        }

     }

}

DES加密：

import java.io.*;

import java.security.*;

import javax.crypto.*;

public class SEnc{

   public static void main(String args[]) throws Exception{

        String s="Hello world!";//需加密的明文

       

        FileInputStream f=new FileInputStream("key1.dat");

        ObjectInputStream b=new ObjectInputStream(f);

        Key k=(Key)b.readObject( );

       

        Cipher cp=Cipher.getInstance("DESede");

        cp.init(Cipher.ENCRYPT_MODE, k);

       

        byte ptext[]=s.getBytes("UTF8");

        for(int i=0;i<ptext.length;i++){

            System.out.print(ptext[i]+",");

        }

       

        System.out.println("");

        byte ctext[]=cp.doFinal(ptext);

        for(int i=0;i<ctext.length;i++){

             System.out.print(ctext[i] +",");

        }

       

        FileOutputStream f2=new FileOutputStream("SEnc.dat");

        f2.write(ctext);

   }

}

密钥加密：

import java.security.*;

import java.security.spec.*;

import javax.crypto.*;

import javax.crypto.spec.*;

import javax.crypto.interfaces.*;

import java.security.interfaces.*;

import java.math.*;

import java.io.*;

public class Enc_RSA{

   public static void main(String args[]) throws Exception{

         FileInputStream  f1=new FileInputStream("keykb1.dat");

        int num2=f1.available();

        byte[ ] keykb=new byte[num2];         

        f1.read(keykb);

 

       

       

        FileInputStream f=new FileInputStream("Skey_RSA_pub.dat");

        ObjectInputStream b=new ObjectInputStream(f);

        RSAPublicKey  pbk=(RSAPublicKey)b.readObject( );

        BigInteger e=pbk.getPublicExponent();

        BigInteger n=pbk.getModulus();

        System.out.println("e= "+e);

        System.out.println("n= "+n);

        //byte ptext[]=s.getBytes("UTF8");

        BigInteger m=new BigInteger(keykb);

        BigInteger c=m.modPow(e,n);

        System.out.println("c= "+c);

        String cs=c.toString( );

        BufferedWriter out=

          new BufferedWriter(new OutputStreamWriter(

            new FileOutputStream("Enc_RSA.dat")));

        out.write(cs,0,cs.length( ));

        out.close( );

      

   }

}

客户端将密文和加密密钥传给服务器端

密钥解密：

import java.security.*;

import java.security.spec.*;

import javax.crypto.*;

import javax.crypto.spec.*;

import javax.crypto.interfaces.*;

import java.security.interfaces.*;

import java.math.*;

import java.io.*;

public class Dec_RSA{

   public static void main(String args[]) throws Exception{

        BufferedReader in=

          new BufferedReader(new InputStreamReader(new FileInputStream("Enc_RSA.dat")));

        String ctext=in.readLine();

        BigInteger c=new BigInteger(ctext);

 

        FileInputStream f=new FileInputStream("Skey_RSA_priv.dat");

        ObjectInputStream b=new ObjectInputStream(f);

        RSAPrivateKey prk=(RSAPrivateKey)b.readObject( );

        BigInteger d=prk.getPrivateExponent();

        BigInteger n=prk.getModulus();

        System.out.println("d= "+d);

        System.out.println("n= "+n);

 

        BigInteger m=c.modPow(d,n);

        System.out.println("m= "+m);

        byte[] mt=m.toByteArray();

        FileOutputStream f2=new FileOutputStream("keyb.dat");

        f2.write(mt);

       

       }

   }

密文解密：

import java.io.*;

import java.security.*;

import javax.crypto.*;

import javax.crypto.spec.*;

public class SDec{

   public static void main(String args[]) throws Exception{

        FileInputStream f=new FileInputStream("SEnc.dat");

        int num=f.available();

        byte[ ] ctext=new byte[num];         

        f.read(ctext);

        //FileInputStream  f2=new FileInputStream("keya.dat");

        FileInputStream  f2=new FileInputStream("keyb.dat");

        int num2=f2.available();

        byte[ ] keykb=new byte[num2];         

        f2.read(keykb);    

 

        SecretKeySpec k=new  SecretKeySpec(keykb,"DESede");

       Cipher cp=Cipher.getInstance("DESede");

       cp.init(Cipher.DECRYPT_MODE, k);

       byte []ptext=cp.doFinal(ctext);

       String p=new String(ptext,"UTF8");

       System.out.println(p);

 

 

   }

}

实验测试

服务器显示：

客户端显示：