简单字符串加密工具

在网上找了一个简单的字符串DES加密解密工具:DesUtil

package com.ftk.eloan.framework.utils;

import java.security.Key;
import java.security.Security;

import javax.crypto.Cipher;

/**
* DES加密 解密算法
*
* @author lifq
* @date 2015-3-17 上午10:12:11
*/
public class DesUtil {
private static String strDefaultKey = "tourhb";

private Cipher encryptCipher = null;

private Cipher decryptCipher = null;

private static DesUtil desUtil;

public static void main(String[] args) {
try {
String test = "43020719800203401X_20170802";
DesUtil des = DesUtil.getInstance(null);// 自定义密钥
System.out.println("加密前的字符：" + test);
System.out.println("加密后的字符：" + des.encrypt(test));
System.out.println("解密后的字符：" + des.decrypt(des.encrypt(test)));

System.out.println("解密后的字符：" + des.decrypt("fe14c7c41f7d2a94b07d7928b21346e7"));

} catch (Exception e) {
e.printStackTrace();
}
}

public static DesUtil getInstance(String key){
if(desUtil == null) {
try {
if(key == null||key.trim().length()<=0){
desUtil = new DesUtil();
}else{
desUtil = new DesUtil(key);
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return desUtil;
}

public static String byteArr2HexStr(byte[] arrB) throws Exception {
int iLen = arrB.length;
// 每个byte用两个字符才能表示，所以字符串的长度是数组长度的两倍
StringBuffer sb = new StringBuffer(iLen * 2);
for (int i = 0; i < iLen; i++) {
int intTmp = arrB[i];
// 把负数转换为正数
while (intTmp < 0) {
intTmp = intTmp + 256;
}
// 小于0F的数需要在前面补0
if (intTmp < 16) {
sb.append("0");
}
sb.append(Integer.toString(intTmp, 16));
}
return sb.toString();
}

public static byte[] hexStr2ByteArr(String strIn) throws Exception {
byte[] arrB = strIn.getBytes();
int iLen = arrB.length;

// 两个字符表示一个字节，所以字节数组长度是字符串长度除以2
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;
}

private DesUtil() throws Exception{

this(strDefaultKey);
}

private DesUtil(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);
}

public byte[] encrypt(byte[] arrB) throws Exception {
return encryptCipher.doFinal(arrB);
}

public String encrypt(String strIn) throws Exception {
return byteArr2HexStr(encrypt(strIn.getBytes()));
}

public byte[] decrypt(byte[] arrB) throws Exception {
return decryptCipher.doFinal(arrB);
}

public String decrypt(String strIn) throws Exception {
try {
return new String(decrypt(hexStr2ByteArr(strIn)));
} catch (Exception e) {
return "";
}
}

private Key getKey(byte[] arrBTmp) throws Exception {
// 创建一个空的8位字节数组（默认值为0）
byte[] arrB = new byte[8];
// 将原始字节数组转换为8位
for (int i = 0; i < arrBTmp.length && i < arrB.length; i++) {
arrB[i] = arrBTmp[i];
}
// 生成密钥
Key key = new javax.crypto.spec.SecretKeySpec(arrB, "DES");
return key;
}
}