java des加解密

为什么选择des加密

          对称算法，数据加密标准，速度较快，适用于加密大量数据的场合，跟目前项目需求较匹配

代码解析

         该加密采用三层加解密，其中加解密分为两类：文件整体加密和文件部分加密，大型文件在加密时耗时较多，所以提供了一个部分加解密，应该能满足绝大多数项目需求

         废话也不多说了，直接上代码

    

package com.tydic.util;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Date;

/**
 * @author dengyichao
 * @Title: Fileencrypter
 * @Package: com.tydic.util
 * @Description:   des加密解密程序
 * @date 2018/5/25  14:30
 */
public class FileencrypterPull {

    /**
     * @Author:    dengyichao
     * @Date:  2018/5/25  16:05
     * @param fileIn
     * @param sKey
     * @param dateStr
     * @param skey2
     * @Description:    加密函数 输入： 要加密的文件，密码，对输入的文件加密后，
     *                    保存到同一文件夹下增加了 "en+原文件名" 为扩展名的文件中。
     */
    public void encrypt(File fileIn, String sKey, String dateStr,String skey2) {
        try {
                byte[] bytK1 = getKeyByStr(sKey);
                byte[] bytK2 = getKeyByStr(dateStr);
                byte[] bytK3 = getKeyByStr(skey2);

                FileInputStream fis = new FileInputStream(fileIn);
                byte[] bytIn = new byte[(int) fileIn.length()];
                for (int i = 0; i < fileIn.length(); i++) {
                    bytIn[i] = (byte) fis.read();
                }
                // 加密
                byte[] bytOut = encryptByDES(encryptByDES(encryptByDES(bytIn,
                        bytK1), bytK2), bytK3);
                String fileOut = fileIn.getParent() + File.separator + "en_"+fileIn.getName();
                FileOutputStream fos = new FileOutputStream(fileOut);
                for (int i = 0; i < bytOut.length; i++) {
                    fos.write((int) bytOut[i]);
                }
                fos.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }


    /**
     *  @Author:    dengyichao
     *  @Date:  2018/5/25  15:51
     *  @param fileIn
     *  @param sKey   uuid
     *  @param dateStr 当前加密时间
     *  @param skey2   uuid
     *  @Description: 解密函数 输入： 要解密的文件，密码  des
     */
    public void decrypt(File fileIn, String sKey, String dateStr,String skey2) {
        FileInputStream fis = null;
        FileOutputStream fos = null;
        try {
                byte[] bytK1 = getKeyByStr(sKey);
                byte[] bytK2 = getKeyByStr(dateStr);
                byte[] bytK3 = getKeyByStr(skey2);
                fis = new FileInputStream(fileIn);
                byte[] bytIn = new byte[(int) fileIn.length()];
                for (int i = 0; i < fileIn.length(); i++) {
                    bytIn[i] = (byte) fis.read();
                }
                // 解密
                byte[] bytOut = decryptByDES(decryptByDES(decryptByDES(bytIn,
                        bytK3), bytK2), bytK1);
                String fileOut = fileIn.getParent() + File.separator + "de_"+fileIn.getName();
                fos = new FileOutputStream(fileOut);
                for (int i = 0; i < bytOut.length; i++) {
                    fos.write((int) bytOut[i]);
                }

                System.out.println("解密成功");
        } catch (Exception e) {
            System.out.println("解密错误！");
        } finally {
            try {
                fos.close();
                fis.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }


    /**
     * @Author:    dengyichao
     * @Date:  2018/5/25  15:54
     * @param bytP  文件
     * @param bytKey   密码
     * @Description:
     */
    private byte[] encryptByDES(byte[] bytP, byte[] bytKey) throws Exception {
        DESKeySpec desKS = new DESKeySpec(bytKey);
        SecretKeyFactory skf = SecretKeyFactory.getInstance("DES");
        SecretKey sk = skf.generateSecret(desKS);
        Cipher cip = Cipher.getInstance("DES");
        cip.init(Cipher.ENCRYPT_MODE, sk);
        return cip.doFinal(bytP);
    }

    /**
     * 用DES方法解密输入的字节 bytKey需为8字节长，是解密的密码
     */
    private byte[] decryptByDES(byte[] bytE, byte[] bytKey) throws Exception {
        DESKeySpec desKS = new DESKeySpec(bytKey);
        SecretKeyFactory skf = SecretKeyFactory.getInstance("DES");
        SecretKey sk = skf.generateSecret(desKS);
        Cipher cip = Cipher.getInstance("DES");
        cip.init(Cipher.DECRYPT_MODE, sk);
        return cip.doFinal(bytE);
    }

    /**
     * 输入密码的字符形式，返回字节数组形式。 如输入字符串：AD67EA2F3BE6E5AD
     * 返回字节数组：{173,103,234,47,59,230,229,173}
     */
    private byte[] getKeyByStr(String str) {
        byte[] bRet = new byte[str.length() / 2];
        for (int i = 0; i < str.length() / 2; i++) {
            Integer itg = new Integer(16 * getChrInt(str.charAt(2 * i))
                    + getChrInt(str.charAt(2 * i + 1)));
            bRet[i] = itg.byteValue();
        }
        return bRet;
    }

    /**
     * 计算一个16进制字符的10进制值 输入：0-F
     */
    private int getChrInt(char chr) {
        int iRet = 0;
        if (chr == "0".charAt(0))
            iRet = 0;
        if (chr == "1".charAt(0))
            iRet = 1;
        if (chr == "2".charAt(0))
            iRet = 2;
        if (chr == "3".charAt(0))
            iRet = 3;
        if (chr == "4".charAt(0))
            iRet = 4;
        if (chr == "5".charAt(0))
            iRet = 5;
        if (chr == "6".charAt(0))
            iRet = 6;
        if (chr == "7".charAt(0))
            iRet = 7;
        if (chr == "8".charAt(0))
            iRet = 8;
        if (chr == "9".charAt(0))
            iRet = 9;
        if (chr == "A".charAt(0))
            iRet = 10;
        if (chr == "B".charAt(0))
            iRet = 11;
        if (chr == "C".charAt(0))
            iRet = 12;
        if (chr == "D".charAt(0))
            iRet = 13;
        if (chr == "E".charAt(0))
            iRet = 14;
        if (chr == "F".charAt(0))
            iRet = 15;
        return iRet;
    }

    /**
     *  @Author:    dengyichao
     *  @Date:  2018/5/28  10:00
     *  @param fileIn
     *  @param sKey
     *  @param dateStr
     *  @param skey2
     *  @Description:   部分加密
     */
    public int encryptPartial(File fileIn, String sKey, String dateStr,String skey2) {
        Integer encryptSize = null;
        try {
            byte[] bytK1 = getKeyByStr(sKey);
            byte[] bytK2 = getKeyByStr(dateStr);
            byte[] bytK3 = getKeyByStr(skey2);
            FileInputStream fis = new FileInputStream(fileIn);
            String fileOut = fileIn.getParent() + File.separator + "en_"+fileIn.getName();
            FileOutputStream fos = new FileOutputStream(fileOut);
            byte[] bytIn = new byte[1024];
            int count = 0;
            while ((fis.read(bytIn))!=-1){
                ++count;
                // 如果
                if(count == 1){
                    bytIn = encryptByDES(encryptByDES(encryptByDES(bytIn,
                            bytK1), bytK2), bytK3);
                    encryptSize = bytIn.length;
                }
                fos.write(bytIn);
            }
            fos.close();
            fis.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return encryptSize;
    }


    /**
     *  @Author:    dengyichao
     *  @Date:  2018/5/28  10:01
     *  @param fileIn
     *  @param sKey
     *  @param dateStr
     *  @param skey2
     *  @param startSize  之前加密时返回的加密长度
     *  @Description:  解析部分加密的数据
     */
    public void decryptPartial(File fileIn, String sKey, String dateStr,String skey2,int startSize) {
        try {
            byte[] bytK1 = getKeyByStr(sKey);
            byte[] bytK2 = getKeyByStr(dateStr);
            byte[] bytK3 = getKeyByStr(skey2);
            FileInputStream fis = new FileInputStream(fileIn);
            String fileOut = fileIn.getParent() + File.separator + "de_"+fileIn.getName();
            FileOutputStream fos = new FileOutputStream(fileOut);
            byte[] bytIn = new byte[startSize];
            int count = 0;
            while ((fis.read(bytIn))!=-1){
                ++count;
                // 如果
                if(count == 1){
                    // 解密
                    bytIn = decryptByDES(decryptByDES(decryptByDES(bytIn,
                            bytK3), bytK2), bytK1);
                    fos.write(bytIn);
                    bytIn = new byte[1024];
                    continue;
                }
                fos.write(bytIn);
            }
            fos.close();
            fis.close();
            System.out.println("解密成功");
        } catch (Exception e) {
            System.out.println("解密错误！");
        }
    }
}