扩展PropertyPlaceholderConfigurer对prop文件中的属性加密

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一、背景

处于安全考虑需要对.properties中的数据库用户名与密码等敏感数据进行加密。项目中使用了Spring3框架统一加载属性文件,所以最好可以干扰这个加载过程来实现对.properties文件中的部分属性进行加密。

属性文件中的属性最初始时敏感属性值可以为明文,程序第一次执行后自动加密明文为密文。

二、问题分析

  1. 扩展PropertyPlaceholderConfigurer最好的方式就是编写一个继承该类的子类。
  2. 外部设置locations时,记录全部locations信息,为加密文件保留属性文件列表。重写setLocations与setLocation方法(在父类中locations私有)
  3. 寻找一个读取属性文件属性的环节,检测敏感属性加密情况。对有已有加密特征的敏感属性进行解密。重写convertProperty方法来实现。
  4. 属性文件第一次加载完毕后,立即对属性文件中的明文信息进行加密。重写postProcessBeanFactory方式来实现。

三、程序开发

1、目录结构

扩展PropertyPlaceholderConfigurer对prop文件中的属性加密

注:aes包中为AES加密工具类,可以根据加密习惯自行修改

2、EncryptPropertyPlaceholderConfigurer(详见注释)

package org.noahx.spring.propencrypt;
import org.noahx.spring.propencrypt.aes.AesUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.config.PropertyPlaceholderConfigurer;
import org.springframework.core.io.Resource;
import java.io.*;
import java.util.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
 * Created with IntelliJ IDEA.
 * User: noah
 * Date: 9/16/13
 * Time: 10:36 AM
 * To change this template use File | Settings | File Templates.
 */
public class EncryptPropertyPlaceholderConfigurer extends PropertyPlaceholderConfigurer {
private static final String SEC_KEY = "@^_^123aBcZ*";
//主密钥
private static final String ENCRYPTED_PREFIX = "Encrypted:{";
private static final String ENCRYPTED_SUFFIX = "}";
private static Pattern encryptedPattern = Pattern.compile("Encrypted:\\{((\\w|\\-)*)\\}");  //加密属性特征正则
private Logger logger = LoggerFactory.getLogger(this.getClass());
private Set<String> encryptedProps = Collections.emptySet();
public void setEncryptedProps(Set<String> encryptedProps) {
this.encryptedProps = encryptedProps;
}
@Override
protected String convertProperty(String propertyName, String propertyValue) {
if (encryptedProps.contains(propertyName)) { //如果在加密属性名单中发现该属性
final Matcher matcher = encryptedPattern.matcher(propertyValue);  //判断该属性是否已经加密
if (matcher.matches()) {
//已经加密,进行解密
String encryptedString = matcher.group(1);
//获得加密值
String decryptedPropValue = AesUtils.decrypt(propertyName + SEC_KEY, encryptedString);  //调用AES进行解密,SEC_KEY与属性名联合做密钥更安全
if (decryptedPropValue != null) {  //!=null说明正常
propertyValue = decryptedPropValue; //设置解决后的值
} else {//说明解密失败
logger.error("Decrypt " + propertyName + "=" + propertyValue + " error!");
}
}
}
return super.convertProperty(propertyName, propertyValue);  //将处理过的值传给父类继续处理
}
@Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
super.postProcessBeanFactory(beanFactory);
//正常执行属性文件加载
for (Resource location : locations) {
//加载完后,遍历location,对properties进行加密
try {
final File file = location.getFile();
if (file.isFile()) {  //如果是一个普通文件
if (file.canWrite()) { //如果有写权限
encrypt(file);   //调用文件加密方法
} else {
if (logger.isWarnEnabled()) {
logger.warn("File '" + location + "' can not be write!");
}
}
} else {
if (logger.isWarnEnabled()) {
logger.warn("File '" + location + "' is not a normal file!");
}
}
} catch (IOException e) {
if (logger.isWarnEnabled()) {
logger.warn("File '" + location + "' is not a normal file!");
}
}
}
}
private boolean isBlank(String str) {
int strLen;
if (str == null || (strLen = str.length()) == 0) {
return true;
}
for (int i = 0; i < strLen; i++) {
if ((Character.isWhitespace(str.charAt(i)) == false)) {
return false;
}
}
return true;
}
private boolean isNotBlank(String str) {
return !isBlank(str);
}
/**
* 属性文件加密方法
*
* @param file
*/
private void encrypt(File file) {
List<String> outputLine = new ArrayList<String>();   //定义输出行缓存
boolean doEncrypt = false;
//是否加密属性文件标识
BufferedReader bufferedReader = null;
try {
bufferedReader = new BufferedReader(new FileReader(file));
String line = null;
do {
line = bufferedReader.readLine(); //按行读取属性文件
if (line != null) { //判断是否文件结束
if (isNotBlank(line)) {   //是否为空行
line = line.trim();
//取掉左右空格
if (!line.startsWith("#")) {//如果是非注释行
String[] lineParts = line.split("=");  //将属性名与值分离
String key = lineParts[0];
// 属性名
String value = lineParts[1];
//属性值
if (key != null && value != null) {
if (encryptedProps.contains(key)) { //发现是加密属性
final Matcher matcher = encryptedPattern.matcher(value);
if (!matcher.matches()) { //如果是非加密格式,则`进行加密
value = ENCRYPTED_PREFIX + AesUtils.encrypt(key + SEC_KEY, value) + ENCRYPTED_SUFFIX;   //进行加密,SEC_KEY与属性名联合做密钥更安全
line = key + "=" + value;  //生成新一行的加密串
doEncrypt = true;
//设置加密属性文件标识
if (logger.isDebugEnabled()) {
logger.debug("encrypt property:" + key);
}
}
}
}
}
}
outputLine.add(line);
}
} while (line != null);
} catch (FileNotFoundException e) {
logger.error(e.getMessage(), e);
} catch (IOException e) {
logger.error(e.getMessage(), e);
} finally {
if (bufferedReader != null) {
try {
bufferedReader.close();
} catch (IOException e) {
logger.error(e.getMessage(), e);
}
}
}
if (doEncrypt) {
//判断属性文件加密标识
BufferedWriter bufferedWriter = null;
File tmpFile = null;
try {
tmpFile = File.createTempFile(file.getName(), null, file.getParentFile());   //创建临时文件
if (logger.isDebugEnabled()) {
logger.debug("Create tmp file '" + tmpFile.getAbsolutePath() + "'.");
}
bufferedWriter = new BufferedWriter(new FileWriter(tmpFile));
final Iterator<String> iterator = outputLine.iterator();
while (iterator.hasNext()) {
//将加密后内容写入临时文件
bufferedWriter.write(iterator.next());
if (iterator.hasNext()) {
bufferedWriter.newLine();
}
}
bufferedWriter.flush();
} catch (IOException e) {
logger.error(e.getMessage(), e);
} finally {
if (bufferedWriter != null) {
try {
bufferedWriter.close();
} catch (IOException e) {
logger.error(e.getMessage(), e);
}
}
}
File backupFile = new File(file.getAbsoluteFile() + "_" + System.currentTimeMillis());  //准备备份文件名
//以下为备份,异常恢复机制
if (!file.renameTo(backupFile)) {   //重命名原properties文件,(备份)
logger.error("Could not encrypt the file '" + file.getAbsoluteFile() + "'! Backup the file failed!");
tmpFile.delete(); //删除临时文件
} else {
if (logger.isDebugEnabled()) {
logger.debug("Backup the file '" + backupFile.getAbsolutePath() + "'.");
}
if (!tmpFile.renameTo(file)) {   //临时文件重命名失败 (加密文件替换原失败)
logger.error("Could not encrypt the file '" + file.getAbsoluteFile() + "'! Rename the tmp file failed!");
if (backupFile.renameTo(file)) {   //恢复备份
if (logger.isInfoEnabled()) {
logger.info("Restore the backup, success.");
}
} else {
logger.error("Restore the backup, failed!");
}
} else {  //(加密文件替换原成功)
if (logger.isDebugEnabled()) {
logger.debug("Rename the file '" + tmpFile.getAbsolutePath() + "' -> '" + file.getAbsoluteFile() + "'.");
}
boolean dBackup = backupFile.delete();//删除备份文件
if (logger.isDebugEnabled()) {
logger.debug("Delete the backup '" + backupFile.getAbsolutePath() + "'.(" + dBackup + ")");
}
}
}
}
}
protected Resource[] locations;
@Override
public void setLocations(Resource[] locations) {   //由于location是父类私有,所以需要记录到本类的locations中
super.setLocations(locations);
this.locations = locations;
}
@Override
public void setLocation(Resource location) {   //由于location是父类私有,所以需要记录到本类的locations中
super.setLocation(location);
this.locations = new Resource[]{location};
}
}

3、spring.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
<context:property-placeholder location="/WEB-INF/spring/spring.properties"/>
<!--对spring.properties配置文件中的指定属性进行加密-->
<bean id="encryptPropertyPlaceholderConfigurer"
class="org.noahx.spring.propencrypt.EncryptPropertyPlaceholderConfigurer">
<property name="locations">
<list>
<value>/WEB-INF/spring/spring.properties</value>
</list>
</property>
<property name="encryptedProps">
<set>
<value>db.jdbc.username</value>
<value>db.jdbc.password</value>
<value>db.jdbc.url</value>
</set>
</property>
</bean>
</beans>

四、运行效果

1、日志

[RMI TCP Connection(2)-127.0.0.1] DEBUG org.noahx.spring.propencrypt.EncryptPropertyPlaceholderConfigurer - encrypt property:db.jdbc.url
[RMI TCP Connection(2)-127.0.0.1] DEBUG org.noahx.spring.propencrypt.EncryptPropertyPlaceholderConfigurer - encrypt property:db.jdbc.username
[RMI TCP Connection(2)-127.0.0.1] DEBUG org.noahx.spring.propencrypt.EncryptPropertyPlaceholderConfigurer - encrypt property:db.jdbc.password
[RMI TCP Connection(2)-127.0.0.1] DEBUG org.noahx.spring.propencrypt.EncryptPropertyPlaceholderConfigurer - Create tmp file '/nautilus/workspaces/idea/spring-prop-encrypt/target/spring-prop-encrypt-1.0-SNAPSHOT/WEB-INF/spring/spring.properties2420183175827237221.tmp'.
[RMI TCP Connection(2)-127.0.0.1] DEBUG org.noahx.spring.propencrypt.EncryptPropertyPlaceholderConfigurer - Backup the file '/nautilus/workspaces/idea/spring-prop-encrypt/target/spring-prop-encrypt-1.0-SNAPSHOT/WEB-INF/spring/spring.properties_1379959755837'.
[RMI TCP Connection(2)-127.0.0.1] DEBUG org.noahx.spring.propencrypt.EncryptPropertyPlaceholderConfigurer - Rename the file '/nautilus/workspaces/idea/spring-prop-encrypt/target/spring-prop-encrypt-1.0-SNAPSHOT/WEB-INF/spring/spring.properties2420183175827237221.tmp' -> '/nautilus/workspaces/idea/spring-prop-encrypt/target/spring-prop-encrypt-1.0-SNAPSHOT/WEB-INF/spring/spring.properties'.
[RMI TCP Connection(2)-127.0.0.1] DEBUG org.noahx.spring.propencrypt.EncryptPropertyPlaceholderConfigurer - Delete the backup '/nautilus/workspaces/idea/spring-prop-encrypt/target/spring-prop-encrypt-1.0-SNAPSHOT/WEB-INF/spring/spring.properties_1379959755837'.(true)

2、原属性文件

db.jdbc.driver=com.mysql.jdbc.Driver
db.jdbc.url=jdbc:mysql://localhost:3306/noah?useUnicode=true&characterEncoding=utf8
db.jdbc.username=noah
db.jdbc.password=noah

3、加密后的文件

db.jdbc.driver=com.mysql.jdbc.Driver
db.jdbc.url=Encrypted:{e5ShuhQjzDZrkqoVdaO6XNQrTqCPIWv8i_VR4zaK28BrmWS_ocagv3weYNdr0WwI}
db.jdbc.username=Encrypted:{z5aneQi_h4mk4LEqhjZU-A}
db.jdbc.password=Encrypted:{v09a0SrOGbw-_DxZKieu5w}
注:因为密钥与属性名有关,所以相同值加密后的内容也不同,而且不能互换值。


五、源码下载

附件地址:http://sdrv.ms/18li77V

六、总结

在成熟加密框架中jasypt(http://www.jasypt.org/)很不错,包含了spring,hibernate等等加密。试用了一些功能后感觉并不太适合我的需要。

加密的安全性是相对的,没有绝对安全的东西。如果有人反编译了加密程序获得了加密解密算法也属正常。希望大家不要因为是否绝对安全而讨论不休。

如果追求更高级别的加密可以考虑混淆class的同时对class文件本身进行加密,改写默认的classloader加载加密class(调用本地核心加密程序,非Java)。

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