在各种体系中，咱们都未免会要用到加密。加密方法分成可还原密文跟不可还原密文两种，可还原密文用得比较广泛、比拟多的就是DES算法了，不可还原的比较多的就是MD5了。本文供给两种算法的相应java实现。有局部函数参考网络实现
1package com.resoft.util;
2
3import java.io.UnsupportedEncodingException;
4import java.security.InvalidKeyException;
5import java.security.MessageDigest;
6import java.security.NoSuchAlgorithmException;
7import java.security.SecureRandom;
8import java.security.spec.InvalidKeySpecException;
9
10import javax.crypto.BadPaddingException;
11import javax.crypto.Cipher;
12import javax.crypto.IllegalBlockSizeException;
13import javax.crypto.NoSuchPaddingException;
14import javax.crypto.SecretKey;
15import javax.crypto.SecretKeyFactory;
16import javax.crypto.spec.DESKeySpec;
17
18import sun.misc.BASE64Encoder;
19
20/** *//**
21 * 保险加密类
22 *
23 * @date 2007-10-31
24 * @author yayagepei
25 *
26 */
27public class SecurityEncode {
28
29 /** *//**
30 * MD5方式加密字符串
31 *
32 * @param str
33 * 要加密的字符串
34 * @return 加密后的字符串
35 * @throws NoSuchAlgorithmException
36 * @throws UnsupportedEncodingException
37 * @author yayagepei
38 * @date 2007-10-31
39 * @comment 程序的价值体当初两个方面:它现在的价值,它将来的价值
40 */
41 public static String encoderByMd5(String str)
42 throws NoSuchAlgorithmException, UnsupportedEncodingException {
43 // 断定盘算方式
44 MessageDigest md5 = MessageDigest.getInstance("MD5");
45 BASE64Encoder base64en = new BASE64Encoder();
46 // 加密后的字符串
47 String newstr = base64en.encode(md5.digest(str.getBytes("utf-8")));
48 return newstr;
49 }
50
51 /** *//**
52 * DES加解密
53 *
54 * @param plainText
55 * 要处置的byte[]
56 * @param key
57 * 密钥
58 * @param mode
59 * 模式
60 * @return
61 * @throws InvalidKeyException
62 * @throws InvalidKeySpecException
63 * @throws NoSuchAlgorithmException
64 * @throws NoSuchPaddingException
65 * @throws BadPaddingException
66 * @throws IllegalBlockSizeException
67 * @throws UnsupportedEncodingException
68 * @author yayagepei
69 * @date 2008-10-8
70 */
71 private static byte[] coderByDES(byte[] plainText, String key, int mode)
72 throws InvalidKeyException, InvalidKeySpecException,
73 NoSuchAlgorithmException, NoSuchPaddingException,
74 BadPaddingException, IllegalBlockSizeException,
75 UnsupportedEncodingException {
76 SecureRandom sr = new SecureRandom();
77 byte[] resultKey = makeKey(key);
78 DESKeySpec desSpec = new DESKeySpec(resultKey);
79 SecretKey secretKey = SecretKeyFactory.getInstance("DES")
80 .generateSecret(desSpec);
81 Cipher cipher = Cipher.getInstance("DES");
82 cipher.init(mode, secretKey, sr);
83 return cipher.doFinal(plainText);
84 }
85
86 /** *//**
87 * 出产8位的key
88 *
89 * @param key
90 * 字符串情势
91 * @return
92 * @throws UnsupportedEncodingException
93 * @author yayagepei
94 * @date 2008-10-8
95 */
96 private static byte[] makeKey(String key)
97 throws UnsupportedEncodingException {
98 byte[] keyByte = new byte[8];
99 byte[] keyResult = key.getBytes("UTF-8");
100 for (int i = 0; i < keyResult.length && i < keyByte.length; i++) {
101 keyByte = keyResult ;
102 }
103 return keyByte;
104 }
105
106 /** *//**
107 * DES加密
108 *
109 * @param plainText
110 * 明文
111 * @param key
112 * 密钥
113 * @return
114 * @author yayagepei
115 * @date 2008-10-8
116 */
117 public static String encoderByDES(String plainText, String key) {
118 try {
119 byte[] result = coderByDES(plainText.getBytes("UTF-8"), key,
120 Cipher.ENCRYPT_MODE);
121 return byteArr2HexStr(result);
122 } catch (Exception ex) {
123 ex.printStackTrace();
124 return "";
125 }
126 }
127
128 /** *//**
129 * DES解密
130 *
131 * @param secretText
132 * 密文
133 * @param key
134 * 密钥
135 * @return
136 * @author yayagepei
137 * @date 2008-10-8
138 */
139 public static String decoderByDES(String secretText, String key) {
140 try {
141 byte[] result = coderByDES(hexStr2ByteArr(secretText), key,
142 Cipher.DECRYPT_MODE);
143 return new String(result, "UTF-8");
144 } catch (Exception ex) {
145 ex.printStackTrace();
146 return "";
147 }
148 }
149
150 /** *//**
151 * 将byte数组转换为表示16进制值的字符串， 如：byte[]{8,18}转换为：0813， 和public static byte[]
152 * hexStr2ByteArr(String strIn) 互为可逆的转换进程
153 *
154 * @param arrB
155 * 须要转换的byte数组
156 * @return 转换后的字符串
157 */
158 private static String byteArr2HexStr(byte[] arrB){
159 int iLen = arrB.length;
160 // 每个byte用两个字符才干表现，所以字符串的长度是数组长度的两倍
161 StringBuffer sb = new StringBuffer(iLen * 2);
162 for (int i = 0; i < iLen; i++) {
163 int intTmp = arrB ;
164 // 把负数转换为正数
165 while (intTmp < 0) {
166 intTmp = intTmp + 256;
167 }
168 // 小于0F的数需要在前面补0
169 if (intTmp < 16) {
170 sb.append("0");
171 }
172 sb.append(Integer.toString(intTmp, 16));
173 }
174 return sb.toString();
175 }
176
177 /** *//**
178 * 将表示16进制值的字符串转换为byte数组， 和public static String byteArr2HexStr(byte[] arrB)
179 * 互为可逆的转换过程
180 *
181 * @param strIn
182 * 需要转换的字符串
183 * @return 转换后的byte数组
184 * @throws NumberFormatException
186 */
187 private static byte[] hexStr2ByteArr(String strIn)
188 throws NumberFormatException {
189 byte[] arrB = strIn.getBytes();
190 int iLen = arrB.length;
191 // 两个字符表示一个字节，所以字节数组长度是字符串长度除以2
192 byte[] arrOut = new byte[iLen / 2];
193 for (int i = 0; i < iLen; i = i + 2) {
194 String strTmp = new String(arrB, i, 2);
195 arrOut = (byte) Integer.parseInt(strTmp, 16);
196 }
197 return arrOut;
198 }
199}
