DES加密使用

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所谓加密，从应用角度就是使用指定的密钥将指定的数据进行加密。

我们不用关心具体算法的实现，只要关心应用本身需求和加密方法的使用即可。

如下是DES加密方法是用的示例，注意使用DES的话密钥长度应该是8的倍数。

package com.util;import java.security.SecureRandom;import javax.crypto.Cipher;import javax.crypto.SecretKey;import javax.crypto.SecretKeyFactory;import javax.crypto.spec.DESKeySpec;public class DESUtil {private static final String PASSWORD_CRYPT_KEY = "01234567";// 示例密钥private final static String DES = "DES";public static void main(String[] args) {System.out.println(encrypt("cuisuqiang", "12345678"));System.out.println(decrypt(encrypt("cuisuqiang", "12345678"),"12345678"));}/** * 加密 * @param src 数据 * @param key 密钥，长度必须是8的倍数 * @return 返回加密后的数据 */private static byte[] encrypt(byte[] src, byte[] key) throws Exception {SecureRandom sr = new SecureRandom();DESKeySpec dks = new DESKeySpec(key);SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);SecretKey securekey = keyFactory.generateSecret(dks);Cipher cipher = Cipher.getInstance(DES);cipher.init(Cipher.ENCRYPT_MODE, securekey, sr);return cipher.doFinal(src);}/** * 解密 * @param src 数据 * @param key 密钥，长度必须是8的倍数 * @return 返回解密后的原始数据 */private static byte[] decrypt(byte[] src, byte[] key) throws Exception {SecureRandom sr = new SecureRandom();DESKeySpec dks = new DESKeySpec(key);SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);SecretKey securekey = keyFactory.generateSecret(dks);Cipher cipher = Cipher.getInstance(DES);cipher.init(Cipher.DECRYPT_MODE, securekey, sr);return cipher.doFinal(src);}/** * 密码加密 */public final static String encrypt(String data, String key) {try {return byte2hex(encrypt(data.getBytes(), key.getBytes()));} catch (Exception e) {e.printStackTrace();}return null;}/** * 密码解密 */public final static String decrypt(String data, String key) {try {return new String(decrypt(hex2byte(data), key.getBytes()));} catch (Exception e) {e.printStackTrace();}return null;}// 字节码转换成16进制字符串private static String byte2hex(byte bytes[]) {StringBuffer retString = new StringBuffer();for (int i = 0; i < bytes.length; ++i) {retString.append(Integer.toHexString(0x0100 + (bytes[i] & 0x00FF)).substring(1).toUpperCase());}return retString.toString();}// 将16进制字符串转换成字节码private static byte[] hex2byte(String hex) {byte[] bts = new byte[hex.length() / 2];for (int i = 0; i < bts.length; i++) {bts[i] = (byte) Integer.parseInt(hex.substring(2 * i, 2 * i + 2),16);}return bts;}}

先加密，再将加密的内容反转。

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