转自李祥:http://blog.csdn.net/happylee6688/article/details/44455407
Java 加解密技术系列之 DES
标签&＃xff1a; 加密解密技术des
2015-03-19 12:04 5093人阅读 收藏 举报
版权声明&＃xff1a;本文为博主原创文章&＃xff0c;未经博主允许不得转载。
目录(?)[-]
- 序
- 背景
- 概念
- 基本原理
- 主要流程
- 分组模式
- 代码实现
- 结束语
序
前几篇文章讲的都是单向加密算法&＃xff0c;其中涉及到了 BASE64、MD5、SHA、HMAC 等几个比较常见的加解密算法。这篇文章&＃xff0c;以及后面几篇&＃xff0c;打算介绍几个对称加密算法&＃xff0c;比如&＃xff1a;DES、3DES&＃xff08;TripleDES&＃xff09;、AES 等。那么&＃xff0c;这篇文章主要是对 DES 大概讲一下。
背景
在讨论 DES 之前&＃xff0c;首先了解一下什么是对称加密算法吧。对于对称加密算法&＃xff0c;他应用的时间比较早&＃xff0c;技术相对来说比较成熟&＃xff0c;在对称加密算法中&＃xff0c;数据发信方将明文&＃xff08;原始数据&＃xff09;和加密密钥一起经过特殊加密算法处理后&＃xff0c;使其变成复杂的加密密文发送出去。收信方收到密文后&＃xff0c;若想解读原文&＃xff0c;则需要使用加密用过的密钥及相同算法的逆算法对密文进行解密&＃xff0c;才能使其恢复成可读明文。
package com.sica.des;import com.google.common.base.Strings;
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.spec.InvalidKeySpecException;/*** Created by xiang.li on 2015/2/28.* DES 加解密工具类** * 支持 DES、DESede(TripleDES,就是3DES)、AES、Blowfish、RC2、RC4(ARCFOUR)* DES key size must be equal to 56* DESede(TripleDES) key size must be equal to 112 or 168* AES key size must be equal to 128, 192 or 256,but 192 and 256 bits may not be available* Blowfish key size must be multiple of 8, and can only range from 32 to 448 (inclusive)* RC2 key size must be between 40 and 1024 bits* RC4(ARCFOUR) key size must be between 40 and 1024 bits* 具体内容 需要关注 JDK Document http://.../docs/technotes/guides/security/SunProviders.html*
*/
public class DES {/*** 定义加密方式*/private final static String KEY_DES &＃61; "DES";private final static String KEY_AES &＃61; "AES"; // 测试/*** 全局数组*/private final static String[] hexDigits &＃61; { "0", "1", "2", "3", "4", "5","6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };/*** 初始化密钥* &＃64;return*/public static String init() {return init(null);}/*** 初始化密钥* &＃64;param seed 初始化参数* &＃64;return*/public static String init(String seed) {SecureRandom secure &＃61; null;String str &＃61; "";try {if (null !&＃61; secure) {// 带参数的初始化secure &＃61; new SecureRandom(decryptBase64(seed));} else {// 不带参数的初始化secure &＃61; new SecureRandom();}KeyGenerator generator &＃61; KeyGenerator.getInstance(KEY_DES);generator.init(secure);SecretKey key &＃61; generator.generateKey();str &＃61; encryptBase64(key.getEncoded());} catch (Exception e) {e.printStackTrace();}return str;}/*** 转换密钥* &＃64;param key 密钥的字节数组* &＃64;return*/private static Key byteToKey(byte[] key) {SecretKey secretKey &＃61; null;try {DESKeySpec dks &＃61; new DESKeySpec(key);SecretKeyFactory factory &＃61; SecretKeyFactory.getInstance(KEY_DES);secretKey &＃61; factory.generateSecret(dks);// 当使用其他对称加密算法时&＃xff0c;如AES、Blowfish等算法时&＃xff0c;用下述代码替换上述三行代码
// secretKey &＃61; new SecretKeySpec(key, KEY_DES);} catch (InvalidKeyException e) {e.printStackTrace();} catch (NoSuchAlgorithmException e) {e.printStackTrace();} catch (InvalidKeySpecException e) {e.printStackTrace();}return secretKey;}/*** DES 解密* &＃64;param data 需要解密的字符串* &＃64;param key 密钥* &＃64;return*/public static String decryptDES(String data, String key) {// 验证传入的字符串if (Strings.isNullOrEmpty(data)) {return "";}// 调用解密方法完成解密byte[] bytes &＃61; decryptDES(hexString2Bytes(data), key);// 将得到的字节数组变成字符串返回return new String(bytes);}/*** DES 解密* &＃64;param data 需要解密的字节数组* &＃64;param key 密钥* &＃64;return*/public static byte[] decryptDES(byte[] data, String key) {byte[] bytes &＃61; null;try {Key k &＃61; byteToKey(decryptBase64(key));Cipher cipher &＃61; Cipher.getInstance(KEY_DES);cipher.init(Cipher.DECRYPT_MODE, k);bytes &＃61; cipher.doFinal(data);} catch (Exception e) {e.printStackTrace();}return bytes;}/*** DES 加密* &＃64;param data 需要加密的字符串* &＃64;param key 密钥* &＃64;return*/public static String encryptDES(String data, String key) {// 验证传入的字符串if (Strings.isNullOrEmpty(data)) {return "";}// 调用加密方法完成加密byte[] bytes &＃61; encryptDES(data.getBytes(), key);// 将得到的字节数组变成字符串返回return byteArrayToHexString(bytes);}/*** DES 加密* &＃64;param data 需要加密的字节数组* &＃64;param key 密钥* &＃64;return*/public static byte[] encryptDES(byte[] data, String key) {byte[] bytes &＃61; null;try {Key k &＃61; byteToKey(decryptBase64(key));Cipher cipher &＃61; Cipher.getInstance(KEY_DES);cipher.init(Cipher.ENCRYPT_MODE, k);bytes &＃61; cipher.doFinal(data);} catch (Exception e) {e.printStackTrace();}return bytes;}/*** BASE64 解密* &＃64;param key 需要解密的字符串* &＃64;return 字节数组* &＃64;throws Exception*/public static byte[] decryptBase64(String key) throws Exception {return (new BASE64Decoder()).decodeBuffer(key);}/*** BASE64 加密* &＃64;param key 需要加密的字节数组* &＃64;return 字符串* &＃64;throws Exception*/public static String encryptBase64(byte[] key) throws Exception {return (new BASE64Encoder()).encodeBuffer(key);}/*** 将一个字节转化成十六进制形式的字符串* &＃64;param b 字节数组* &＃64;return 字符串*/private static String byteToHexString(byte b) {int ret &＃61; b;//System.out.println("ret &＃61; " &＃43; ret);if (ret <0) {ret &＃43;&＃61; 256;}int m &＃61; ret / 16;int n &＃61; ret % 16;return hexDigits[m] &＃43; hexDigits[n];}/*** 转换字节数组为十六进制字符串* &＃64;param bytes 字节数组* &＃64;return 十六进制字符串*/private static String byteArrayToHexString(byte[] bytes) {StringBuffer sb &＃61; new StringBuffer();for (int i &＃61; 0; i &＃61; &＃39;a&＃39;)return (c - &＃39;a&＃39; &＃43; 10) & 0x0f;if (c >&＃61; &＃39;A&＃39;)return (c - &＃39;A&＃39; &＃43; 10) & 0x0f;return (c - &＃39;0&＃39;) & 0x0f;}/*** 测试方法* &＃64;param args*/public static void main(String[] args) {String key &＃61; DES.init();System.out.println("DES密钥:\n" &＃43; key);String word &＃61; "123";String encWord &＃61; encryptDES(word, key);System.out.println(word &＃43; "\n加密后&＃xff1a;\n" &＃43; encWord);System.out.println(word &＃43; "\n解密后&＃xff1a;\n" &＃43; decryptDES(encWord, key));}
}
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