python和java中Des加密初试

来源：互联网发布：制作毕业证软件编辑：程序博客网时间：2024/05/16 11:50

项目中需要做一个Des加密，牵扯好几家单位，但人家都用java来实现，只用调用相同的代码就好，而我们后台用的python。我初步想到有两种办法来解决这个问题：1、用python来实现des加密功能，保证相同的字符串通过java和python加密出来的密文相同；2、如果第一条行不通，就需要直接利用他们的加密算法，然后想办法用python来调用，以实现加密。

首先对Des算法做简单了解，见百度百科：数据加密算法。此处对具体实现过程不做讨论。

接下来看java实现Des加密的算法：

package com.core.util;
 
import java.security.Key;
import java.text.SimpleDateFormat;
import java.util.Date;
 
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESedeKeySpec;
import javax.crypto.spec.IvParameterSpec;
 
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;
 
public class DesUtil {
    private final static String encoding = "utf-8";
    
    private static String getIVToday(){
        return new SimpleDateFormat("yyyyMMdd").format(new Date());
    }
    
    private static String getIVYesterday(){
        return new SimpleDateFormat("yyyyMMdd").format(new Date(new Date().getTime()-86400000));
    }
    
    private static String getIVTomorrow(){
        return new SimpleDateFormat("yyyyMMdd").format(new Date(new Date().getTime()+86400000));
    }
    
    private static String getSecretKeyToday(){
        return "qaz_"+getIVToday()+"_wsx";
    }
    
    private static String getSecretKeyYesterday(){
        return "qaz_"+getIVYesterday()+"_wsx";
    }
    
    private static String getSecretKeyTomorrow(){
        return "qaz_"+getIVTomorrow()+"_wsx";
    }
    
    /**
     * 加密
     * @param plainText
     * @return
     */
    public static String encode(String plainText) {
        Key deskey = null;
        byte[] encryptData = null;
        String secretKey = getSecretKeyToday();
        try {
            DESedeKeySpec spec = new DESedeKeySpec(secretKey.getBytes());
            SecretKeyFactory keyfactory = SecretKeyFactory.getInstance("desede");
            deskey = keyfactory.generateSecret(spec);
 
            Cipher cipher = Cipher.getInstance("desede/CBC/PKCS5Padding");
            IvParameterSpec ips = new IvParameterSpec(getIVToday().getBytes());
            cipher.init(Cipher.ENCRYPT_MODE, deskey, ips);
            encryptData = cipher.doFinal(plainText.getBytes(encoding));
            
            BASE64Encoder base64Encoder = new BASE64Encoder();
            return base64Encoder.encode(encryptData);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "";
    }
    
    /**
     * 解密
     * @param data
     * @return
     */
    public static String decode(String data){
        try {
            Key deskey = null;
            String secretKey = getSecretKeyToday();
            DESedeKeySpec spec = new DESedeKeySpec(secretKey.getBytes());
            SecretKeyFactory keyfactory = SecretKeyFactory.getInstance("desede");
            deskey = keyfactory.generateSecret(spec);
            Cipher deCipher = Cipher.getInstance("desede/CBC/PKCS5Padding");
            IvParameterSpec ips = new IvParameterSpec(getIVToday().getBytes());
            deCipher.init(Cipher.DECRYPT_MODE, deskey, ips);
            
            BASE64Decoder base64Decoder = new BASE64Decoder();
            byte[] pasByte = null;
            try{
                pasByte=deCipher.doFinal(base64Decoder.decodeBuffer(data));
            }catch(BadPaddingException e){
                secretKey = getSecretKeyYesterday();
                spec = new DESedeKeySpec(secretKey.getBytes());
                deskey = keyfactory.generateSecret(spec);
                ips = new IvParameterSpec(getIVYesterday().getBytes());
                deCipher.init(Cipher.DECRYPT_MODE, deskey, ips);
                try{
                    pasByte=deCipher.doFinal(base64Decoder.decodeBuffer(data));
                }catch(BadPaddingException e1){
                    secretKey = getSecretKeyTomorrow();
                    spec = new DESedeKeySpec(secretKey.getBytes());
                    deskey = keyfactory.generateSecret(spec);
                    ips = new IvParameterSpec(getIVTomorrow().getBytes());
                    deCipher.init(Cipher.DECRYPT_MODE, deskey, ips);
                    
                    pasByte=deCipher.doFinal(base64Decoder.decodeBuffer(data));
                }
            }
            return new String(pasByte,"UTF-8");
        } catch (Exception e) {}
        return "";
    }
 
    public static void main(String[] args) {
            System.out.println(DesUtil.encode("phonenum=12345678901"));
    }
 }

以上代码中，最为关键的就是了解Cipher类，3.3.5 Cipher类。

python实现Des加密的基本思路：1、自己重写Des加密算法 python实现DES加密 2、调用pyDes：

from pyDes import *

# For Python3, you'll need to use bytes, i.e.:
#   data = b"Please encrypt my data"
#   k = des(b"DESCRYPT", CBC, b"\0\0\0\0\0\0\0\0", pad=None, padmode=PAD_PKCS5)

data = "userPhone=12345678901"
k = triple_des("123456781234567812345678", CBC, "\0\0\0\0\0\0\0\0", pad=None, padmode=PAD_PKCS5)
d = k.encrypt(data)
print "Encrypted: %r" % d
print "Decrypted: %r" % k.decrypt(d)
assert k.decrypt(d, padmode=PAD_PKCS5) == data

其中triple_des中要求秘钥为16位或24位，des方法需要8位。

但两种形式中，可传递的参数只有需加密字符串和秘钥（长度为8的倍数），并没有java中那个随机向量的概念。由于没有时间研究Cipher的源码，所以用python来实现以上java算法算是泡汤了。下一篇文章说明如何使用JPype实现python调用java代码。

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