Des加密和解密

package aaaa;
import java.security.InvalidAlgorithmParameterException;
import java.security.Key;
import java.security.spec.AlgorithmParameterSpec;
import java.util.Locale;
import javax.crypto.Cipher;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import javax.crypto.spec.IvParameterSpec;
/**
 * 
 * @ClassName: com.qust.rollcallstudent.utils.DESUtil
 * @Description: DES加密解密工具包
 * @author zhaokaiqiang
 * @date 2014-11-13 下午8:40:56
 * 
 */
public class DESUtil {
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 InvalidAlgorithmParameterException
* @throws Exception
*/
public static String encode(String key, String data) {
if (data == null)
return null;
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.getBytes());
return byte2String(bytes);
} catch (Exception e) {
e.printStackTrace();
return data;
}
}
/**
* 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
*/
public static String decode(String key, String data) {
if (data == null)
return null;
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 new String(cipher.doFinal(byte2hex(data.getBytes())));
} catch (Exception e) {
e.printStackTrace();
return data;
}
}
/**
* 二行制转字符串
* 
* @param b
* @return
*/
private static String byte2String(byte[] b) {
StringBuilder hs = new StringBuilder();
String stmp;
for (int n = 0; b != null && n < b.length; n++) {
stmp = Integer.toHexString(b[n] & 0XFF);
if (stmp.length() == 1)
hs.append('0');
hs.append(stmp);
}
return hs.toString().toUpperCase(Locale.CHINA);
}
/**
* 二进制转化成16进制
* 
* @param b
* @return
*/
private static byte[] byte2hex(byte[] b) {
if ((b.length % 2) != 0)
throw new IllegalArgumentException();
byte[] b2 = new byte[b.length / 2];
for (int n = 0; n < b.length; n += 2) {
String item = new String(b, n, 2);
b2[n / 2] = (byte) Integer.parseInt(item, 16);
}
return b2;
}
}