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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;

                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

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