Java 的DES算法实现

package des;

import java.security.Key;
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;

/**
*
* 使用DES加密与解密,可对byte[],String类型进行加密与解密 密文可使用String,byte[]存储.
* 方法: void getKey(String strKey)从strKey的字条生成一个Key
* String getEncString(String strMing)对strMing进行加密,返回String密文 String
* getDesString(String strMi)对strMin进行解密,返回String明文
* byte[] getEncCode(byte[] byteS)byte[]型的加密 byte[] getDesCode(byte[]
* byteD)byte[]型的解密
*/



public class DesEncrypt {

Key key;

/**

* 根据参数生成KEY
* @param strKey
*/

public void getKey(String strKey) {

try {

KeyGenerator _generator = KeyGenerator.getInstance("DES");

_generator.init(new SecureRandom(strKey.getBytes()));

this.key = _generator.generateKey();

_generator = null;

} catch (Exception e) {

e.printStackTrace();

}

}



/**

* 加密String明文输入,String密文输出
* @param strMing
* @return
*/

public String getEncString(String strMing) {

byte[] byteMi = null;

byte[] byteMing = null;

String strMi = "";

try {

return byte2hex(getEncCode(strMing.getBytes()));



// byteMing = strMing.getBytes("UTF8");

// byteMi = this.getEncCode(byteMing);

// strMi = new String( byteMi,"UTF8");

} catch (Exception e) {

e.printStackTrace();

} finally {

byteMing = null;

byteMi = null;

}

return strMi;

}



/**

* 解密 以String密文输入,String明文输出
* @param strMi
* @return
*/

public String getDesString(String strMi) {

byte[] byteMing = null;

byte[] byteMi = null;

String strMing = "";

try {

return new String(getDesCode(hex2byte(strMi.getBytes())));



// byteMing = this.getDesCode(byteMi);

// strMing = new String(byteMing,"UTF8");

} catch (Exception e) {

e.printStackTrace();

} finally {

byteMing = null;

byteMi = null;

}

return strMing;

}



/**

* 加密以byte[]明文输入,byte[]密文输出
* @param byteS
* @return
*/

private byte[] getEncCode(byte[] byteS) {

byte[] byteFina = null;

Cipher cipher;

try {

cipher = Cipher.getInstance("DES");

cipher.init(Cipher.ENCRYPT_MODE, key);

byteFina = cipher.doFinal(byteS);

} catch (Exception e) {

e.printStackTrace();

} finally {

cipher = null;

}

return byteFina;

}



/**

* 解密以byte[]密文输入,以byte[]明文输出
* @param byteD
* @return
*/

private byte[] getDesCode(byte[] byteD) {

Cipher cipher;

byte[] byteFina = null;

try {

cipher = Cipher.getInstance("DES");

cipher.init(Cipher.DECRYPT_MODE, key);

byteFina = cipher.doFinal(byteD);

} catch (Exception e) {

e.printStackTrace();

} finally {

cipher = null;

}

return byteFina;

}



/**

* 二行制转字符串
*
* @param b
* @return
*/

public static String byte2hex(byte[] b) { // 一个字节的数，

// 转成16进制字符串

String hs = "";

String stmp = "";

for (int n = 0; n < b.length; n++) {

// 整数转成十六进制表示

stmp = (java.lang.Integer.toHexString(b[n] & 0XFF));

if (stmp.length() == 1)

hs = hs + "0" + stmp;

else

hs = hs + stmp;

}

return hs.toUpperCase(); // 转成大写

}



public static byte[] hex2byte(byte[] b) {

if ((b.length % 2) != 0)

throw new IllegalArgumentException("长度不是偶数");

byte[] b2 = new byte[b.length / 2];

for (int n = 0; n < b.length; n += 2) {

String item = new String(b, n, 2);

// 两位一组，表示一个字节,把这样表示的16进制字符串，还原成一个进制字节

b2[n / 2] = (byte) Integer.parseInt(item, 16);

}



return b2;

}



public static void main(String[] args) {



System.out.println("hello");

DesEncrypt des = new DesEncrypt(); //实例化一个对像

des.getKey("aadd"); //生成密匙



String strEnc = des.getEncString("云海飞舞雲122"); //加密字符串,返回String的密文

System.out.println(strEnc);



String strDes = des.getDesString(strEnc); //把String 类型的密文解密

System.out.println(strDes);

new DesEncrypt();

}