20145235实验五

实验内容

掌握Socket程序的编写 掌握密码技术的使用 设计安全传输系统

实验步骤

• 坑货队友唐振远，我是服务器
• 首先查找自己的IP
  • 
• 建立一个Socket对象
  • 
• 双方下载好秘钥
  • 
• 运行代码
  • 
• 连接成功，我也收到了对方发来的信息。

代码

import java.net.*;
import java.io.*;
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.*;
public class ComputeTCPServer{
    public static void main(String srgs[]) throws Exception
    {
        ServerSocket sc = null;
        Socket socket=null;
        try
        {
            sc= new ServerSocket(9999);//创建服务器套接字
            System.out.println("端口号:" + sc.getLocalPort());
            System.out.println("服务器已经启动...");
            socket = sc.accept();   //等待客户端连接
            System.out.println("已经建立连接");//获得网络输入流对象的引用
            BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));//获得网络输出流对象的引用
            PrintWriter out=new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())),true);

            //使用服务器端RSA的私钥对DES的密钥进行解密
            String aline2=in.readLine();
            BigInteger c=new BigInteger(aline2);
            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();
            BigInteger m=c.modPow(d,n);
            byte[] keykb=m.toByteArray();

            //使用DES对密文进行解密
            String aline=in.readLine();//读取客户端传送来的数据
            byte[] ctext=parseHexStr2Byte(aline);
            Key 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("从客户端接收到信息为："+p); //通过网络输出流返回结果给客户端

            //使用Hash函数检测明文完整性
            String aline3=in.readLine();
            String x=p;
            MessageDigest m2=MessageDigest.getInstance("MD5");
            m2.update(x.getBytes( ));
            byte a[ ]=m2.digest( );
            String result="";
            for (int i=0; i<a.length; i++)
            {
                result+=Integer.toHexString((0x000000ff & a[i]) |
                        0xffffff00).substring(6);
            }
            System.out.println(result);

            if(aline3.equals(result))
            {
                System.out.println("匹配成功");
            }

            out.println("匹配成功");
            out.close();
            in.close();
            sc.close();
        } catch (Exception e) {
            System.out.println(e);
        }
    }
    public static byte[] parseHexStr2Byte(String hexStr)
    {
        if (hexStr.length() < 1)
            return null;
        byte[] result = new byte[hexStr.length()/2];
        for (int i = 0;i< hexStr.length()/2; i++)
        {
            int high = Integer.parseInt(hexStr.substring(i*2, i*2+1 ), 16);
            int low = Integer.parseInt(hexStr.substring(i*2+1, i*2+2), 16);
            result[i] = (byte) (high * 16 + low);
        }
        return result;
    }
    public static String parseByte2HexStr(byte buf[]) {
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < buf.length; i++)
        {
            String hex = Integer.toHexString(buf[i] & 0xFF);
            if (hex.length() == 1)
            {
                hex = '0' + hex;
            }
            sb.append(hex.toUpperCase());
        }
        return sb.toString();
    }

}