Java 的DES算法实现

        昨天按照网上的资料写DES,但最后在byte[]->String上卡住了.DES需要8位解密,而这种转换后,会讲btye[]补位造成长度和内容改变.很郁闷....最后又在网上找了一个已经实现的例子运行后无问题:

代码如下:

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;elsehs = 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();}}