JAVA實現DES加密和解密__JAVA

DES.java

import java.security.*;import javax.crypto.*;/** * DES加解密演算法 */public class DES {private static String strDefaultKey = "abcDEF123";private Cipher encryptCipher = null;private Cipher decryptCipher = null;/** * 預設構造方法，使用預設密鑰 * @throws Exception */public DES() throws Exception {this(strDefaultKey);}/** * 指定密鑰構造方法 * @param strKey 指定的密鑰 * @throws Exception */public DES(String strKey) throws Exception {Security.addProvider(new com.sun.crypto.provider.SunJCE());Key key = getKey(strKey.getBytes());encryptCipher = Cipher.getInstance("DES");encryptCipher.init(Cipher.ENCRYPT_MODE, key);decryptCipher = Cipher.getInstance("DES");decryptCipher.init(Cipher.DECRYPT_MODE, key);}/** * 加密字串 * @param strIn 需加密的字串 * @return 加密後的字串 * @throws Exception */public String encrypt(String strIn) throws Exception {return byteArr2HexStr(encrypt(strIn.getBytes()));}/** * 加密位元組數組 * @param arrB 需加密的位元組數組 * @return 加密後的位元組數組 * @throws Exception */public byte[] encrypt(byte[] arrB) throws Exception {return encryptCipher.doFinal(arrB);}/** * 解密字串 * @param strIn 需解密的字串 * @return 解密後的字串 * @throws Exception */public String decrypt(String strIn) throws Exception {return new String(decrypt(hexStr2ByteArr(strIn)));}/** * 解密位元組數組 * @param arrB 需解密的位元組數組 * @return 解密後的位元組數組 * @throws Exception */public byte[] decrypt(byte[] arrB) throws Exception {return decryptCipher.doFinal(arrB);}/** * 從指定字串產生密鑰，密鑰所需的位元組數組長度為8位 * 不足8位時後面補0，超出8位只取前8位 * @param arrBTmp 構成該字串的位元組數組 * @return 產生的密鑰 * @throws java.lang.Exception */private Key getKey(byte[] arrBTmp) throws Exception {byte[] arrB = new byte[8];for (int i = 0; i < arrBTmp.length && i < arrB.length; i++) {arrB[i] = arrBTmp[i];}Key key = new javax.crypto.spec.SecretKeySpec(arrB, "DES");return key;}/** * 將byte數群組轉換為表示16進位值的字串， * 如：byte[]{8,18}轉換為：0813， * 和public static byte[] hexStr2ByteArr(String strIn) * 互為可逆的轉換過程 * @param arrB 需要轉換的byte數組 * @return 轉換後的字串 * @throws Exception 本方法不處理任何異常，所有異常全部拋出 */public static String byteArr2HexStr(byte[] arrB) throws Exception {int iLen = arrB.length;StringBuffer sb = new StringBuffer(iLen * 2);for (int i = 0; i < iLen; i++) {int intTmp = arrB[i];while (intTmp < 0) {intTmp = intTmp + 256;}if (intTmp < 16) {sb.append("0");}sb.append(Integer.toString(intTmp, 16));}return sb.toString();}/** * 將表示16進位值的字串轉換為byte數組， * 和public static String byteArr2HexStr(byte[] arrB) * 互為可逆的轉換過程 * @param strIn 需要轉換的字串 * @return 轉換後的byte數組 * @throws Exception 本方法不處理任何異常，所有異常全部拋出 */public static byte[] hexStr2ByteArr(String strIn) throws Exception {byte[] arrB = strIn.getBytes();int iLen = arrB.length;byte[] arrOut = new byte[iLen / 2];for (int i = 0; i < iLen; i = i + 2) {String strTmp = new String(arrB, i, 2);arrOut[i / 2] = (byte) Integer.parseInt(strTmp, 16);}return arrOut;}}

EncryUtil.java

/** * 加密解密工具類 */public class EncryUtil {/** * 使用預設密鑰進行DES加密 */public static String encrypt(String plainText) {try {return new DES().encrypt(plainText);} catch (Exception e) {return null;}}/** * 使用指定密鑰進行DES解密 */public static String encrypt(String plainText, String key) {try {return new DES(key).encrypt(plainText);} catch (Exception e) {return null;}}/** * 使用預設密鑰進行DES解密 */public static String decrypt(String plainText) {try {return new DES().decrypt(plainText);} catch (Exception e) {return null;}}/** * 使用指定密鑰進行DES解密 */public static String decrypt(String plainText, String key) {try {return new DES(key).decrypt(plainText);} catch (Exception e) {return null;}}}

TestDES.java

public class TestDES {public static void main(String[] args) throws Exception {String str = "01234ABCDabcd!@#$";String t = "";System.out.println("加密後：" + (t = EncryUtil.encrypt(str)));System.out.println("解密後：" + EncryUtil.decrypt(t));}}