2018-2019-2 20175311 实验五《网络编程与安全》实验报告
实验要求
- 完成云班课中的检查点，也可以先完成实验报告，直接提交。注意不能只有截图，要有知识点，原理，遇到的问题和解决过程等说明。
- 实验报告中一个检查点要有多张截图。发表实验报告博客，标题“学期（如2018-2019-2） 学号（如20175300） 实验五《网络编程与安全》实验报告”
实验步骤
实验一
实验要求
两人一组结对编程：
（1）参考http://www.cnblogs.com/rocedu/p/6766748.html#SECDSA ；（2）结对实现中缀表达式转后缀表达式的功能 MyBC.java；
（3）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；
（4）上传测试代码运行结果截图和码云链接；
实验代码：
(1)MyDC.java代码
import java.util.*;
public class MyDC {
private final char ADD = '+';
private final char SUBTRACT = '-';
private final char MUTIPLY = '*';
private final char DIVIDE = '/';
private Stack<Integer> 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)) {
op2 = (stack.pop().intValue());
op1 = (stack.pop().intValue());
result = evalSingleOp(token.charAt(0), op1, op2);
stack.push(result);
} else {
stack.push((Integer.parseInt(token)));
}
}
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 MUTIPLY:
result = op1 * op2;
break;
case DIVIDE:
result = op1 / op2;
}
return result;
}
}
(2）MyBC.java代码
import java.util.*;
public class MyBC {
public static String infixToSuffix(String infix) {
return null;
}
public String result(String s) {
Stack<String> sta = new Stack<String>(); //新建栈
String str = "";
StringTokenizer t=new StringTokenizer(s);
while (t.hasMoreTokens()){ //依次遍历元素，转为后缀表达式
String temp;
String c;
c=t.nextToken();
if (c.equals("+") || c.equals("-")) { //遇到优先级最低的“+”、“-”，弹出“（”之前的所有元素
while (sta.size() != 0) {
temp = sta.pop();
if (temp.equals("(")) {
sta.push("(");
break;
}
str = str + temp + " ";
}
sta.push(c);
} else if (c.equals("*")|| c.equals("÷")) { //遇到优先级高的“*”、“/”，弹出“（”之前的“*”、“/”
while (sta.size() != 0) {
temp = sta.pop();
if (temp.equals("(") || temp.equals("+") || temp.equals("-")) {
sta.push(temp);
break;
} else {
str = str + temp + " ";
}
}
sta.push(c);
} else if (c.equals("(")) { //遇到“(”直接入栈
sta.push(c);
} else if (c.equals(")")) { //遇到“）”，弹出“（”之前的所有元素
while (sta.size() != 0) {
temp = sta.pop();
if (temp.equals("(")) {
break;
} else {
str = str + temp + " ";
}
}
} else //遇到数字，直接存入数组
{
str = str + c + " ";
}
}
while (sta.size()!=0){ //弹出栈中剩余的元素
str=str+sta.pop()+" ";
}
return str;
}
}
（3）MyDCTest.java代码
import java.util.Scanner;
public class MyDCTest {
public static void main (String[] args) {
String expression, again;
int result;
try
{
Scanner in = new Scanner(System.in);
do
{
MyDC evaluator = new MyDC();
System.out.println ("Enter a valid postfix expression: ");
expression = in.nextLine();
result = evaluator.evaluate (expression);
System.out.println();System.out.println ("That expression equals " + result);
System.out.print ("Evaluate another expression [Y/N]? ");
again = in.nextLine();
System.out.println();
}
while (again.equalsIgnoreCase("y"));
}
catch (Exception IOException)
{
System.out.println("Input exception reported");
}
}
}
实验结果
实验二
实验要求
结对编程：1人负责客户端，一人负责服务器；
（1）注意责任归宿，要会通过测试证明自己没有问题；
（2）基于Java Socket实现客户端/服务器功能，传输方式用TCP；
（3）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；
（4）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；
（5）客户端显示服务器发送过来的结果；
（6）上传测试结果截图和码云链接；
实验代码：
（1）Server.java代码
import java.io.*;
import java.net.*;
public class Server {
public static void main(String args[]) {
int answer;
ServerSocket serverForClient=null;
Socket socketOnServer=null;
DataOutputStream out=null;
DataInputStream in=null;
try { serverForClient = new ServerSocket(2010);
}
catch(IOException e1) {
System.out.println(e1);
}
try{ System.out.println("等待客户呼叫");
socketOnServer = serverForClient.accept(); //堵塞状态，除非有客户呼叫
out=new DataOutputStream(socketOnServer.getOutputStream());
in=new DataInputStream(socketOnServer.getInputStream());
String s=in.readUTF(); // in读取信息，堵塞状态
System.out.println("服务器收到客户的提问:"+s);
MyDC d=new MyDC();
answer=d.evaluate(s);
String s1=String.valueOf(answer);
out.writeUTF(s1);
Thread.sleep(500);
}
catch(Exception e) {
System.out.println("客户已断开"+e);
}
}
}
（2）Client.java代码
import java.io.*;
import java.net.*;
import java.lang.*;
import java.util.Scanner;
public class Client {
public static void main(String args[]) {
Socket mysocket;
DataInputStream in=null;
DataOutputStream out=null;
try{ mysocket=new Socket("192.168.1.110",2010);
in=new DataInputStream(mysocket.getInputStream());
out=new DataOutputStream(mysocket.getOutputStream());
System.out.println("请输入算式：");
Scanner scanner=new Scanner(System.in);
String str=scanner.nextLine();
MyBC b=new MyBC();
str=b.result(str);
out.writeUTF(str);
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);
}
catch(Exception e) {
System.out.println("服务器已断开"+e);
}
}
}
实验结果
实验三
实验要求
加密结对编程：1人负责客户端，一人负责服务器；
（1）注意责任归宿，要会通过测试证明自己没有问题；
（2）基于Java Socket实现客户端/服务器功能，传输方式用TCP；
（3）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；
（4）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；
（5）客户端显示服务器发送过来的结果；
（6）上传测试结果截图和码云链接；
实验代码
（1）Client2.java代码
import java.io.*;
import java.net.*;
import java.lang.*;
import java.util.Scanner;
public class Client2 {
public static void main(String args[]) throws Exception {
String key = "";
int n = -1;
byte[] a = new byte[128];
try {
File f = new File("key1.dat");
InputStream in = new FileInputStream(f);
while ((n = in.read(a, 0, 100)) != -1) {
key = key + new String(a, 0, n);
}
in.close();
} catch (IOException e) {
System.out.println("File read Error" + e);
}
Socket mysocket;
DataInputStream in = null;
DataOutputStream out = null;
System.out.println("请输入算式：");
Scanner scanner = new Scanner(System.in);
String str = scanner.nextLine();//输入算式
MyBC b = new MyBC();
str = b.result(str);
String secret=Encoder.AESEncode(key,str);//客户端进行加密
try {
mysocket = new Socket("127.1.0.0", 2010);
in = new DataInputStream(mysocket.getInputStream());
out = new DataOutputStream(mysocket.getOutputStream());
out.writeUTF(key);
out.writeUTF(secret);
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);
} catch (Exception e) {
System.out.println("服务器已断开" + e);
}
}
}
（2）Server2.java代码
import java.io.*;
import java.net.*;
import java.security.Key;
public class Server2 {
public static void main (String args[]) throws Exception {
/*String key="";
int n=-1;
byte [] a=new byte[128];
try{ File f=new File("key1.dat");
InputStream in = new FileInputStream(f);
while((n=in.read(a,0,100))!=-1) {
key=key+new String (a,0,n);
}
in.close();
}
catch(IOException e) {
System.out.println("File read Error"+e);
}*/
ServerSocket serverForClient=null;
Socket socketOnServer=null;
DataOutputStream out=null;
DataInputStream in=null;
try { serverForClient = new ServerSocket(2010);
}
catch(IOException e1) {
System.out.println(e1);
}
try{ System.out.println("等待客户呼叫");
socketOnServer = serverForClient.accept(); //堵塞状态，除非有客户呼叫
out=new DataOutputStream(socketOnServer.getOutputStream());
in=new DataInputStream(socketOnServer.getInputStream());
String key = in.readUTF();
String s=in.readUTF(); // in读取信息，堵塞状态
FileInputStream f=new FileInputStream("key1.dat");
ObjectInputStream b=new ObjectInputStream(f);
Key k=(Key)b.readObject( );
byte[ ] kb=k.getEncoded( );
FileOutputStream f2=new FileOutputStream("keykb1.dat");
f2.write(kb);
// 打印密钥编码中的内容
for(int i=0;i<kb.length;i++){
System.out.print(kb[i]+",");
}
System.out.println();
System.out.println("服务器收到的信息:"+s);
String clear=Encoder.AESDncode(key,s);
MyDC d=new MyDC();
System.out.println("服务器收到客户的提问:"+clear);
int answer=d.evaluate(clear);
out.writeUTF(answer+"");
Thread.sleep(500);
}
catch(Exception e) {
System.out.println("客户已断开"+e);
}
}
}
（3）Encoder.java代码（加解密代码）
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;
/*
* AES对称加密和解密
*/
public class Encoder {
/*
* 加密
* 1.构造密钥生成器
* 2.根据ecnodeRules规则初始化密钥生成器
* 3.产生密钥
* 4.创建和初始化密码器
* 5.内容加密
* 6.返回字符串
*/
public static String AESEncode(String encodeRules,String content){
try {
//1.构造密钥生成器，指定为AES算法,不区分大小写
KeyGenerator keygen=KeyGenerator.getInstance("AES");
//2.根据ecnodeRules规则初始化密钥生成器
//生成一个128位的随机源,根据传入的字节数组
keygen.init(128, new SecureRandom(encodeRules.getBytes()));
//3.产生原始对称密钥
SecretKey original_key=keygen.generateKey();
//4.获得原始对称密钥的字节数组
byte [] raw=original_key.getEncoded();
//5.根据字节数组生成AES密钥
SecretKey key=new SecretKeySpec(raw, "AES");
//6.根据指定算法AES自成密码器
Cipher cipher=Cipher.getInstance("AES");
//7.初始化密码器，第一个参数为加密(Encrypt_mode)或者解密解密(Decrypt_mode)操作，第二个参数为使用的KEY
cipher.init(Cipher.ENCRYPT_MODE, key);
//8.获取加密内容的字节数组(这里要设置为utf-8)不然内容中如果有中文和英文混合中文就会解密为乱码
byte [] byte_encode=content.getBytes("utf-8");
//9.根据密码器的初始化方式--加密：将数据加密
byte [] byte_AES=cipher.doFinal(byte_encode);
//10.将加密后的数据转换为字符串
//这里用Base64Encoder中会找不到包
//解决办法：
//在项目的Build path中先移除JRE System Library，再添加库JRE System Library，重新编译后就一切正常了。
String AES_encode=new String(new BASE64Encoder().encode(byte_AES));
//11.将字符串返回
return AES_encode;
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
} catch (NoSuchPaddingException e) {
e.printStackTrace();
} catch (InvalidKeyException e) {
e.printStackTrace();
} catch (IllegalBlockSizeException e) {
e.printStackTrace();
} catch (BadPaddingException e) {
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
//如果有错就返加nulll
return null;
}
/*
* 解密
* 解密过程：
* 1.同加密1-4步
* 2.将加密后的字符串反纺成byte[]数组
* 3.将加密内容解密
*/
public static String AESDncode(String encodeRules,String content){
try {
//1.构造密钥生成器，指定为AES算法,不区分大小写
KeyGenerator keygen=KeyGenerator.getInstance("AES");
//2.根据ecnodeRules规则初始化密钥生成器
//生成一个128位的随机源,根据传入的字节数组
keygen.init(128, new SecureRandom(encodeRules.getBytes()));
//3.产生原始对称密钥
SecretKey original_key=keygen.generateKey();
//4.获得原始对称密钥的字节数组
byte [] raw=original_key.getEncoded();
//5.根据字节数组生成AES密钥
SecretKey key=new SecretKeySpec(raw, "AES");
//6.根据指定算法AES自成密码器
Cipher cipher=Cipher.getInstance("AES");
//7.初始化密码器，第一个参数为加密(Encrypt_mode)或者解密(Decrypt_mode)操作，第二个参数为使用的KEY
cipher.init(Cipher.DECRYPT_MODE, key);
//8.将加密并编码后的内容解码成字节数组
byte [] byte_content= new BASE64Decoder().decodeBuffer(content);
/*
* 解密
*/
byte [] byte_decode=cipher.doFinal(byte_content);
String AES_decode=new String(byte_decode,"utf-8");
return AES_decode;
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
} catch (NoSuchPaddingException e) {
e.printStackTrace();
} catch (InvalidKeyException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (IllegalBlockSizeException e) {
e.printStackTrace();
} catch (BadPaddingException e) {
e.printStackTrace();
}
//如果有错就返加nulll
return null;
}
}
（4）Skey_AES.java代码
import java.io.*;
import javax.crypto.*;
public class Skey_AES{
public static void main(String args[]) throws Exception{
KeyGenerator kg=KeyGenerator.getInstance("AES");
kg.init(128);
SecretKey k=kg.generateKey( );
FileOutputStream f=new FileOutputStream("key1.dat");
ObjectOutputStream b=new ObjectOutputStream(f);
b.writeObject(k);
}
}
实验结果
实验四
实验要求
密钥分发结对编程：1人负责客户端，一人负责服务器；
（1）注意责任归宿，要会通过测试证明自己没有问题；
（2）基于Java Socket实现客户端/服务器功能，传输方式用TCP；
（3）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；
（4）客户端和服务器用DH算法进行3DES或AES算法的密钥交换；
（5）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；
（6）客户端显示服务器发送过来的结果；
（7）上传测试结果截图和码云链接；
实验代码
（1）Key_DH代码
import java.io.*;
import java.math.*;
import java.security.*;
import java.security.spec.*;
import javax.crypto.*;
import javax.crypto.spec.*;
import javax.crypto.interfaces.*;
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("Serverpub.dat");
ObjectOutputStream b1=new ObjectOutputStream(f1);
b1.writeObject(pbk);
FileOutputStream f2=new FileOutputStream("Clientpub.dat");
ObjectOutputStream b2=new ObjectOutputStream(f2);
b2.writeObject(pbk);
// 保存私钥
FileOutputStream f3=new FileOutputStream("Clientpri.dat");
ObjectOutputStream b3=new ObjectOutputStream(f3);
b3.writeObject(prk);
FileOutputStream f4=new FileOutputStream("Serverpri.dat");
ObjectOutputStream b4=new ObjectOutputStream(f4);
b4.writeObject(prk);
}
}
（2）KeyAgree代码
import java.io.*;
import java.security.*;
import javax.crypto.*;
import javax.crypto.spec.*;
public class KeyAgree{
public KeyAgree(){}
public static SecretKeySpec KeyAgree(String a,String b) throws Exception{
// 读取对方的DH公钥
FileInputStream f1=new FileInputStream(a);
ObjectInputStream b1=new ObjectInputStream(f1);
PublicKey pbk=(PublicKey)b1.readObject( );
//读取自己的DH私钥
FileInputStream f2=new FileInputStream(b);
ObjectInputStream b2=new ObjectInputStream(f2);
PrivateKey prk=(PrivateKey)b2.readObject( );
// 执行密钥协定
KeyAgreement ka=KeyAgreement.getInstance("DH");
ka.init(prk);
ka.doPhase(pbk,true);
//生成共享信息
byte[ ] s=ka.generateSecret();
byte []sb = new byte[24];
System.arraycopy(s, 0, sb, 0, 24);
System.out.println("共享秘钥：");
for(int i=0;i<sb.length;i++){
System.out.print(sb[i]+" ");
}
System.out.println();
SecretKeySpec k=new SecretKeySpec(sb,"DESede");
return k;
}
}
(3)Server3代码（服务端）
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.io.*;
import java.net.*;
public class Server3 {
public static void main(String[] args) {
ServerSocket serverForClient = null;
Socket socketOnServer = null;
DataOutputStream out = null;
DataInputStream in = null;
MyDC myDC = new MyDC();
try{
serverForClient = new ServerSocket(2010);
}catch (IOException e1){
System.out.println("等待客户呼叫"+e1);
}
try{
System.out.println("服务器收到的信息");
socketOnServer = serverForClient.accept();
out = new DataOutputStream(socketOnServer.getOutputStream());
in = new DataInputStream(socketOnServer.getInputStream());
//获取密文
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);
}
//获取密钥
String keylength = in.readUTF();
byte []ckey = new byte[Integer.parseInt(keylength)];
for(int i=0; i<Integer.parseInt(keylength); i++){
String temp = in.readUTF();
ckey[i] = Byte.parseByte(temp);
}
//密钥解密
SecretKeySpec k1 = KeyAgree.KeyAgree("Clientpub.dat","Serverpri.dat");
Cipher cp=Cipher.getInstance("DESede");
cp.init(Cipher.DECRYPT_MODE, k1);
byte []pkey=cp.doFinal(ckey);
//密文解密
SecretKeySpec k=new SecretKeySpec(pkey,"DESede");
cp.init(Cipher.DECRYPT_MODE, k);
byte []ptext=cp.doFinal(ctext);
String suffix = new String(ptext,"UTF8");
System.out.println("服务器提供的解密"+suffix);
out.writeUTF(myDC.evaluate(suffix)+"");
Thread.sleep(500);
}catch (Exception e){
System.out.println("客户已断开");
}
}
}
(4)Client3代码（客户端）
import javax.crypto.spec.*;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.net.Socket;
import java.util.Scanner;
public class Client3 {
public static void main(String[] args) {
Scanner inn = new Scanner(System.in);
Socket mysocket;
DataInputStream in = null;
DataOutputStream out = null;
try {
mysocket = new Socket("127.1.0.0", 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();
System.out.println("请输入中缀表达式：");
String infix = inn.nextLine();
MyBC myBC1 = new MyBC();
String suffix = MyBC.infixToSuffix(infix);
System.out.println(suffix);
//中缀表达式加密
Cipher cp = Cipher.getInstance("DESede");
cp.init(Cipher.ENCRYPT_MODE, k);
byte ptext[] = suffix.getBytes("UTF8");
byte ctext[] = cp.doFinal(ptext);
out.writeUTF(ctext.length + "");
for (int i = 0; i < ctext.length; i++) {
out.writeUTF(ctext[i] + "");
}
//对密钥进行加密
KeyAgree keyAgree = new KeyAgree();
SecretKeySpec k1 = keyAgree.KeyAgree("Serverpub.dat","Clientpri.dat");
cp.init(Cipher.ENCRYPT_MODE, k1);
byte ckey[] = cp.doFinal(kb);
out.writeUTF(ckey.length + "");
for (int i = 0; i < ckey.length; i++) {
out.writeUTF(ckey[i] + "");
}
String result = in.readUTF();
System.out.println("收到客户回答" + result);
Thread.sleep(500);
} catch (Exception e) {
System.out.println("服务器已断开" + e);
}
}
}
实验结果
这个实验存在一些问题还没有完全弄懂，没有办法将密钥存入文件中在运行时再读入，其中给出的文件也没有办法生成。
实验五
实验要求
完整性校验结对编程：1人负责客户端，一人负责服务器；
（1）注意责任归宿，要会通过测试证明自己没有问题；
（2）基于Java Socket实现客户端/服务器功能，传输方式用TCP；
（3）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和明文的MD5値发送给服务器；
（4）客户端和服务器用DH算法进行3DES或AES算法的密钥交换；
（5）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；
（6）客户端显示服务器发送过来的结果；
（7）上传测试结果截图和码云链接；
实验代码
（1）DigestPass代码
import java.security.*;
public class DigestPass{
static String MD5(String str) throws Exception{
MessageDigest m=MessageDigest.getInstance("MD5");
m.update(str.getBytes("UTF8"));
byte s[ ]=m.digest( );
String result="";
for (int i=0; i<s.length; i++){
result+=Integer.toHexString((0x000000ff & s[i]) |
0xffffff00).substring(6);
}
return result;
}
}
（2）Server4代码（服务端）
import java.io.*;
import java.net.*;
public class Server4 {
public static void main(String args[]) throws IOException{
String sharekey="";
int n=-1;
byte [] a=new byte[128];
try{ File f=new File("Sharekey.dat");
InputStream in = new FileInputStream(f);
while((n=in.read(a,0,100))!=-1) {
sharekey=sharekey+new String (a,0,n);
}
in.close();
}
catch(IOException e) {
System.out.println("File read Error"+e);
}
ServerSocket serverForClient=null;
Socket socketOnServer=null;
DataOutputStream out=null;
DataInputStream in=null;
try { serverForClient = new ServerSocket(2010);
}
catch(IOException e1) {
System.out.println(e1);
}
try{ System.out.println("等待客户呼叫");
socketOnServer = serverForClient.accept(); //堵塞状态，除非有客户呼叫
out=new DataOutputStream(socketOnServer.getOutputStream());
in=new DataInputStream(socketOnServer.getInputStream());
String keyone =in.readUTF();//读取被DH算法加密的密钥
String truekey = Encoder.AESDncode(sharekey,keyone);//使用共享密钥对被加密的原密钥解密。
String secret =in.readUTF(); // in读取信息，堵塞状态
System.out.println("服务器收到的信息:"+secret);
String mdClient=in.readUTF();
System.out.println("客户端提供的MD5为:"+ mdClient);
String clear = Encoder.AESDncode(truekey,secret);//使用原密钥解密表达式
MyDC d=new MyDC();
int answer=d.evaluate(clear);
if((mdClient.equals(DigestPass.MD5(clear)))==true) {//判断MD5值是否相等，若相等，则返回答案
System.out.println("MD5值匹配");
System.out.println("服务器提供的解密:" + clear);
System.out.println("服务器解出密文的MD5为:" + DigestPass.MD5(clear));
out.writeUTF(answer + "");
}
Thread.sleep(500);
}
catch(Exception e) {
System.out.println("客户已断开"+e);
}
}
}
（3）Client4代码（客户端）
import java.io.*;
import java.net.*;
import java.util.Scanner;
public class Client4 {
public static void main(String args[]) throws Exception {
String key1="";
int n1=-1;
byte [] a1=new byte[128];
try{ File f=new File("key1.dat");
InputStream in = new FileInputStream(f);
while((n1=in.read(a1,0,100))!=-1) {
key1=key1+new String (a1,0,n1);
}
in.close();
}
catch(IOException e) {
System.out.println("File read Error"+e);
}
String sharekey="";
int n=-1;
byte [] a=new byte[128];
try{ File f=new File("Sharekey.dat");
InputStream in = new FileInputStream(f);
while((n=in.read(a,0,100))!=-1) {
sharekey=sharekey+new String (a,0,n);
}
in.close();
}
catch(IOException e) {
System.out.println("File read Error"+e);
}
Socket mysocket;
DataInputStream in=null;
DataOutputStream out=null;
System.out.println("请输入算式：");
Scanner scanner = new Scanner(System.in);
String str = scanner.nextLine();//输入算式
MyBC b=new MyBC();
str=b.result(str);
String secret=Encoder.AESEncode(key1, str);//客户端对表达式进行加密
String md=DigestPass.MD5(str);//客户端提供的MD5
key1 = Encoder.AESEncode(sharekey,key1);//客户端对密钥进行DH加密
try{ mysocket=new Socket("127.1.0.0",2010);
in=new DataInputStream(mysocket.getInputStream());
out=new DataOutputStream(mysocket.getOutputStream());
out.writeUTF(key1);
out.writeUTF(secret);
out.writeUTF(md);
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(50000);
}
catch(Exception e) {
System.out.println("服务器已断开"+e);
}
}
}
实验结果
