android 施用des算法

转自：http://www.linuxidc.com/Linux/2011-08/41866.htm?稍有改动

import java.security.Key;
import java.security.spec.AlgorithmParameterSpec;

import javax.crypto.Cipher;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import javax.crypto.spec.IvParameterSpec;

import android.util.Base64;

public class DesUtils {
?public static final String ALGORITHM_DES = "DES/CBC/PKCS5Padding";

?/**
? * DES算法，加密
? * @param data 待加密字符串
? * @param key 加密私钥，长度不能够小于8位
? * @return 加密后的字节数组，一般结合Base64编码使用
? * @throws CryptException 异常
? */
?public static String encode(String key, String data) throws Exception {
??return encode(key, data.getBytes());
?}

?/**
? * DES算法，加密
? * @param data? 待加密字符串
? * @param key? 加密私钥，长度不能够小于8位
? * @return 加密后的字节数组，一般结合Base64编码使用
? * @throws CryptException
? *???????????? 异常
? */
?private static String encode(String key, byte[] data) throws Exception {
??try {
???DESKeySpec dks = new DESKeySpec(key.getBytes());
???SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
???// key的长度不能够小于8位字节
???Key secretKey = keyFactory.generateSecret(dks);
???Cipher cipher = Cipher.getInstance(ALGORITHM_DES);
???IvParameterSpec iv = new IvParameterSpec("12345678".getBytes());
???AlgorithmParameterSpec paramSpec = iv;
???cipher.init(Cipher.ENCRYPT_MODE, secretKey, paramSpec);
???byte[] bytes = cipher.doFinal(data);
???return Base64.encodeToString(bytes, 0);
??} catch (Exception e) {
???throw new Exception(e);
??}
?}

?/**
? * DES算法，解密
? * @param data? 待解密字符串
? * @param key 解密私钥，长度不能够小于8位
? * @return 解密后的字节数组
? * @throws Exception? 异常
? */
?private static byte[] decode(String key, byte[] data) throws Exception {
??try {
???DESKeySpec dks = new DESKeySpec(key.getBytes());
???SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
???// key的长度不能够小于8位字节
???Key secretKey = keyFactory.generateSecret(dks);
???Cipher cipher = Cipher.getInstance(ALGORITHM_DES);
???IvParameterSpec iv = new IvParameterSpec("12345678".getBytes());
???AlgorithmParameterSpec paramSpec = iv;
???cipher.init(Cipher.DECRYPT_MODE, secretKey, paramSpec);
???return cipher.doFinal(data);
??} catch (Exception e) {
???throw new Exception(e);
??}
?}
?

?/**
? * 解密.
? * @param key
? * @param data
? * @return
? * @throws Exception
? */
?public static String decode(String key, String data) {
??byte[] datas;
??String value = null;
??try {
???if (System.getProperty("os.name") != null
?????&& (System.getProperty("os.name").equalsIgnoreCase("sunos") || System
???????.getProperty("os.name").equalsIgnoreCase("linux"))) {
????datas = decode(key, Base64.decode(data, 0));
???} else {
????datas = decode(key, Base64.decode(data, 0));
???}

???value = new String(datas);
??} catch (Exception e) {
???value = "";
??}
??return value;
?}

}