java DES加密解密实现

java DES加密解密实现：
步骤一：定义一个通用的十六进制工具类

package com.client;/** * This class provides convenient functions to convert hex string to byte array and vice versa. * */public class HexUtil {    private HexUtil() {    }    /**     * Converts a byte array to hex string.     *      * @param b -     *            the input byte array     * @return hex string representation of b.     */    public static String toHexString(byte[] b) {        StringBuffer sb = new StringBuffer();        for (int i = 0; i < b.length; i++) {            sb.append(HexUtil.HEX_CHARS.charAt(b[i] >>> 4 & 0x0F));            sb.append(HexUtil.HEX_CHARS.charAt(b[i] & 0x0F));        }        return sb.toString();    }    /**     * Converts a hex string into a byte array.     *      * @param s -     *            string to be converted     * @return byte array converted from s     */    public static byte[] toByteArray(String s) {        byte[] buf = new byte[s.length() / 2];        int j = 0;        for (int i = 0; i < buf.length; i++) {            buf[i] = (byte) ((Character.digit(s.charAt(j++), 16) << 4) | Character                    .digit(s.charAt(j++), 16));        }        return buf;    }    private static final String HEX_CHARS = "0123456789abcdef";}

步骤二：des 加解密工具类实现

package com.client;import java.io.UnsupportedEncodingException;import java.security.InvalidKeyException;import java.security.NoSuchAlgorithmException;import java.security.SecureRandom;import javax.crypto.BadPaddingException;import javax.crypto.Cipher;import javax.crypto.IllegalBlockSizeException;import javax.crypto.KeyGenerator;import javax.crypto.NoSuchPaddingException;import javax.crypto.SecretKey;import javax.crypto.SecretKeyFactory;import javax.crypto.spec.DESKeySpec;import javax.crypto.spec.SecretKeySpec;/** * <p> * Title: <B>DES encryption and decryption using Java Crypto </B> * </p> * <p> * Description: * </p> * This class provides a decryption and encryption service based on DES (Data * Encryption Standard). It always generates a key on encryption. On decryption, * it uses the embedded key. As such, it is not really secure and only prevents * simple attacks. In addition, the channel on which it is being used is * supposed to be secure. */public final class DESUtil {    private DESUtil() {    }    private static final String ALGORITHM_OPTIONS = "DES/ECB/PKCS5Padding";    private static final String ALGORITHM_KEY = "DES";    private static final String ALGORITHM_ENCODING = "UTF-8";    private static final String PASSWORD_CRYPT_KEY = "__PAY__DES__KINGO__";    /**     * Encrypts the provided clear text and returns encoded data as a string of     * hex char representations.     *      * @param clearText     *            Clear text to be encrypted     * @return String with the encrypted data of hex char.     */    public static String encrypt(String clearText,String key) {        String keyValue = null;        try {            // DES算法要求有一个可信任的随机数源            SecureRandom sr = new SecureRandom();            // 从原始密匙数据创建DESKeySpec对象            DESKeySpec dks = new DESKeySpec(key.getBytes());            // 创建一个密匙工厂，然后用它把DESKeySpec转换成            // 一个SecretKey对象            SecretKeyFactory keyFactory = SecretKeyFactory                    .getInstance(ALGORITHM_KEY);            SecretKey securekey = keyFactory.generateSecret(dks);            // Cipher对象实际完成加密操作            Cipher cipher = Cipher.getInstance(ALGORITHM_KEY);            // 用密匙初始化Cipher对象            cipher.init(Cipher.ENCRYPT_MODE, securekey, sr);            // 现在，获取数据并加密            // 正式执行加密操作            keyValue = HexUtil                    .toHexString(cipher.doFinal(clearText.getBytes()));        } catch (Exception e) {            keyValue = null;            e.printStackTrace();        }        if (keyValue == null) {            keyValue = "NOKEY " + clearText;        }        return keyValue;    }    /**     *  解密     */    public static String encrypt(String clearText) {        return encrypt(clearText,PASSWORD_CRYPT_KEY);    }    /**     *  加密     */    public static String decrypt(String encryptedText){        return decrypt(encryptedText,PASSWORD_CRYPT_KEY);    }    public static String decrypt(String encryptedText,String key){        String clearText = null;        try{        // DES算法要求有一个可信任的随机数源         SecureRandom sr = new SecureRandom();         // 从原始密匙数据创建一个DESKeySpec对象         DESKeySpec dks = new DESKeySpec(key.getBytes());         // 创建一个密匙工厂，然后用它把DESKeySpec对象转换成         // 一个SecretKey对象         SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGORITHM_KEY);         SecretKey securekey = keyFactory.generateSecret(dks);         // Cipher对象实际完成解密操作         Cipher cipher = Cipher.getInstance(ALGORITHM_KEY);         // 用密匙初始化Cipher对象         cipher.init(Cipher.DECRYPT_MODE, securekey, sr);         // 现在，获取数据并解密         // 正式执行解密操作         byte[] dataPart = HexUtil.toByteArray(encryptedText);        byte[] decryptedData = cipher.doFinal(dataPart);        clearText = new String(decryptedData, ALGORITHM_ENCODING);        }catch(Exception e){            clearText = null;        }        return clearText;       }    public static String encryptRandom(String clearText) {        String keyValue = null;        try {            // generate a secret key            KeyGenerator kg = KeyGenerator.getInstance(ALGORITHM_KEY);            kg.init(56);            SecretKey key = kg.generateKey();            // get the encoded value for the string and convert to hex            byte[] encodedKey = key.getEncoded();            keyValue = HexUtil.toHexString(encodedKey);            keyValue += " ";            // run the encryption algorithm            Cipher cipher = Cipher.getInstance(ALGORITHM_OPTIONS);            cipher.init(Cipher.ENCRYPT_MODE, key);            keyValue += HexUtil.toHexString(cipher.doFinal(clearText                    .getBytes(ALGORITHM_ENCODING)));            /*             * None of below exceptions should happen in runtime because we do             * both the encoding and the decoding and we assert a very common             * encrypt algorthm (DES). That is why we ignore them. Later on, we             * can add log4j to log these unexpected exceptions.             */        } catch (IllegalStateException e) {            keyValue = null;        } catch (IllegalBlockSizeException e) {            keyValue = null;        } catch (BadPaddingException e) {            keyValue = null;        } catch (NoSuchAlgorithmException e) {            keyValue = null;        } catch (NoSuchPaddingException e) {            keyValue = null;        } catch (InvalidKeyException e) {            keyValue = null;        } catch (UnsupportedEncodingException e) {            keyValue = null;        }        if (keyValue == null) {            keyValue = "NOKEY " + clearText;        }        return keyValue;    }    /**     * Decrypts the string, which is supposed to have been encrypted with above     * encrypt function.     *      * @param encryptedText     *            encrypted text to be decrypted     * @return String with the decrypted data.     */    public static String decryptRandom(String encryptedText) {        String clearText = null;        // split the hex into key and data parts.        int spaceLoc = encryptedText.indexOf(' ');        String encryptKey = encryptedText.substring(0, spaceLoc);        String encryptData = encryptedText.substring(spaceLoc + 1);        // special case of no encryption        if (encryptKey.equals("NOKEY")) {            return encryptData;        }        // convert hex data to byte array        byte[] keyPart = HexUtil.toByteArray(encryptKey);        byte[] dataPart = HexUtil.toByteArray(encryptData);        // reconstruct the secret key        SecretKeySpec sks = new SecretKeySpec(keyPart, ALGORITHM_KEY);        try {            // decrypt using the recovered key spec            Cipher cipher = Cipher.getInstance(ALGORITHM_OPTIONS);            cipher.init(Cipher.DECRYPT_MODE, sks);            byte[] decryptedData = cipher.doFinal(dataPart);            clearText = new String(decryptedData, ALGORITHM_ENCODING);        } catch (NoSuchAlgorithmException e) {            clearText = null;        } catch (NoSuchPaddingException e) {            clearText = null;        } catch (InvalidKeyException e) {            clearText = null;        } catch (IllegalStateException e) {            clearText = null;        } catch (IllegalBlockSizeException e) {            clearText = null;        } catch (BadPaddingException e) {            clearText = null;        } catch (UnsupportedEncodingException e) {            clearText = null;        }        return clearText;    }    public static void main(String[] args){        System.out.println("DES加密：" + encrypt("2222222"));        System.out.println("DES解密：" + decrypt("df4cd223373955dd"));    }}

步骤三：运行des加解密工具类中main方法，对比检测程序结果，如下

DES加密：df4cd223373955dd
DES解密：2222222