疯狂

package com.test;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.security.MessageDigest;
import java.security.SecureRandom;
import java.util.Arrays;

//使用md5和盐验证安全登陆
public class Test_MD5 {

 private static final String PWD_FILE = "c:\\pwd.txt";
 /**
  * @param args
  */
 public static void main(String[] args) throws Exception{
  
       
  //用户创建密码，服务端杂凑并保存
  saveMessagePwdInFile("admin");
  ////验证用户输入
  checkUserPwd("admin1");
    
  
 }
 public static void saveMessagePwdInFile(String inputPwd)throws Exception{
  byte[] salt = new byte[8];
  SecureRandom random = new SecureRandom();
  random.nextBytes(salt);
  System.out.println("生成的盐："+Arrays.toString(salt));
  
  MessageDigest digest = MessageDigest.getInstance("MD5");//当然可以使用SHA（160位），MD5(128位)
  digest.update(salt);
  digest.update(inputPwd.getBytes("utf-8"));
  byte[] afterMd5 = digest.digest();
  System.out.println("杂凑值："+Arrays.toString(afterMd5));
  
  //盐和杂凑值写入文件
  FileOutputStream outputStream = new FileOutputStream(new File(PWD_FILE));
  FileChannel channel = outputStream.getChannel();
  channel.write(ByteBuffer.wrap(salt));
  channel.write(ByteBuffer.wrap(afterMd5));
  outputStream.flush();
  outputStream.close();
  System.out.println("保存信息完毕...");
  
 }
 public static void checkUserPwd(String pwd)throws Exception{
  ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
  FileInputStream fileInputStream = new FileInputStream(new File(PWD_FILE));
  FileChannel channel2 = fileInputStream.getChannel();
  ByteBuffer dst = ByteBuffer.allocate(1024);
  int l = -1;
  while((l=channel2.read(dst))!=-1){
   dst.flip();
   byteArrayOutputStream.write(dst.array(),0,l);
   dst.compact();
   dst.clear();
  }
  fileInputStream.close();
  byte[] pwdbyte = byteArrayOutputStream.toByteArray();
  byteArrayOutputStream.reset();
  
  byte[] salt2 = new byte[8];
  System.arraycopy(pwdbyte, 0, salt2, 0, 8);
  System.out.println("从文件获取盐："+Arrays.toString(salt2));
  byte[] pwdinfile = new byte[pwdbyte.length-8];
  System.arraycopy(pwdbyte, 8, pwdinfile, 0, pwdbyte.length-8);
  System.out.println("从文件获取杂凑值："+Arrays.toString(pwdinfile));
     byte[] toyz = getUserMd5Pwd(salt2,pwd);
     System.out.println(Arrays.equals(toyz, pwdinfile)==true?"登陆成功":"密码有误，登录失败...");
 }
 
   public static byte[] getUserMd5Pwd(byte[] salt,String pwd) throws Exception{
    MessageDigest digest2 = MessageDigest.getInstance("MD5");
  digest2.update(salt);
     digest2.update(pwd.getBytes("utf-8"));
     byte[] toyz = digest2.digest();
    
     System.out.println("用户输入杂凑值："+Arrays.toString(toyz));
     return toyz;
   }
}