背景
最近针对公司框架进行关键业务代码进行加密处理，防止通过jd-gui等反编译工具能够轻松还原工程代码，相关混淆方案配置使用比较复杂且针对springboot项目问题较多，所以针对class文件加密再通过自定义的classloder进行解密加载，此方案并不是绝对安全，只是加大反编译的困难程度，防君子不防小人，整体加密保护流程图如下图所示
maven插件加密
使用自定义maven插件对编译后指定的class文件进行加密，加密后的class文件拷贝到指定路径，这里是保存到resource/coreclass下，删除源class文件，加密使用的是简单的DES对称加密
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@Parameter (name = "protectClassNames" , defaultValue = "" ) private List<String> protectClassNames; @Parameter (name = "noCompileClassNames" , defaultValue = "" ) private List<String> noCompileClassNames; private List<String> protectClassNameList = new ArrayList<>(); private void protectCore(File root) throws IOException { if (root.isDirectory()) { for (File file : root.listFiles()) { protectCore(file); } } String className = root.getName().replace( ".class" , "" ); if (root.getName().endsWith( ".class" )) { //class筛选 boolean flag = false ; if (protectClassNames!= null && protectClassNames.size()> 0 ) { for (String item : protectClassNames) { if (className.equals(item)) { flag = true ; } } } if (noCompileClassNames.contains(className)){ boolean deleteResult = root.delete(); if (!deleteResult){ System.gc(); deleteResult = root.delete(); } System.out.println( "【noCompile-deleteResult】:" + deleteResult); } if (flag && !protectClassNameList.contains(className)) { protectClassNameList.add(className); System.out.println( "【protectCore】:" + className); FileOutputStream fos = null ; try { final byte [] instrumentBytes = doProtectCore(root); //加密后的class文件保存路径 String folderPath = output.getAbsolutePath() + "\\" + "classes" ; File folder = new File(folderPath); if (!folder.exists()){ folder.mkdir(); } folderPath = output.getAbsolutePath() + "\\" + "classes" + "\\" + "coreclass" ; folder = new File(folderPath); if (!folder.exists()){ folder.mkdir(); } String filePath = output.getAbsolutePath() + "\\" + "classes" + "\\" + "coreclass" + "\\" + className + ".class" ; System.out.println( "【filePath】：" + filePath); File protectFile = new File(filePath); if (protectFile.exists()) { protectFile.delete(); } protectFile.createNewFile(); fos = new FileOutputStream(protectFile); fos.write(instrumentBytes); fos.flush(); } catch (MojoExecutionException e) { System.out.println( "【protectCore-exception】:" + className); e.printStackTrace(); } finally { if (fos != null ) { fos.close(); } if (root.exists()){ boolean deleteResult = root.delete(); if (!deleteResult){ System.gc(); deleteResult = root.delete(); } System.out.println( "【protectCore-deleteResult】:" + deleteResult); } } } } } private byte [] doProtectCore(File clsFile) throws MojoExecutionException { try { FileInputStream inputStream = new FileInputStream(clsFile); byte [] content = ProtectUtil.encrypt(inputStream); inputStream.close(); return content; } catch (Exception e) { throw new MojoExecutionException( "doProtectCore error" , e); } } |
注意事项
1.加密后的文件也是class文件，为了防止在递归查找中重复加密，需要对已经加密后的class名称记录防止重复
2.在删除源文件时可能出现编译占用的情况，执行System.gc()后方可删除
3.针对自定义插件的列表形式的configuration节点可以使用List来映射
插件使用配置如图所示
自定义classloader
创建CustomClassLoader继承自ClassLoader，重写findClass方法只处理装载加密后的class文件，其他class交有默认加载器处理，需要注意的是默认处理不能调用super.finclass方法，在idea调试没问题，打成jar包运行就会报加密的class中的依赖class无法加载（ClassNoDefException/ClassNotFoundException），这里使用的是当前线程的上下文的类加载器就没有问题（Thread.currentThread().getContextClassLoader()）
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public class CustomClassLoader extends ClassLoader { @Override protected Class<?> findClass(String name) throws ClassNotFoundException { Class<?> clz = findLoadedClass(name); //先查询有没有加载过这个类。如果已经加载，则直接返回加载好的类。如果没有，则加载新的类。 if (clz != null ) { return clz; } String[] classNameList = name.split( "\\." ); String classFileName = classNameList[classNameList.length - 1 ]; if (classFileName.endsWith( "MethodAccess" ) || !classFileName.endsWith( "CoreUtil" )) { return Thread.currentThread().getContextClassLoader().loadClass(name); } ClassLoader parent = this .getParent(); try { //委派给父类加载 clz = parent.loadClass(name); } catch (Exception e) { //log.warn("parent load class fail："+ e.getMessage(),e); } if (clz != null ) { return clz; } else { byte [] classData = null ; ClassPathResource classPathResource = new ClassPathResource( "coreclass/" + classFileName + ".class" ); InputStream is = null ; try { is = classPathResource.getInputStream(); classData = DESEncryptUtil.decryptFromByteV2(FileUtil.convertStreamToByte(is), "xxxxxxx" ); } catch (Exception e) { e.printStackTrace(); throw new ProtectClassLoadException( "getClassData error" ); } finally { try { if (is != null ) { is.close(); } } catch (IOException e) { e.printStackTrace(); } } if (classData == null ) { throw new ClassNotFoundException(); } else { clz = defineClass(name, classData, 0 , classData.length); } return clz; } } } |
隐藏classloader
classloader加密class文件处理方案的漏洞在于自定义类加载器是完全暴露的，只需进行分析解密流程就能获取到原始class文件，所以我们需要对classloder的内容进行隐藏
1.把classloader的源文件在编译期间进行删除（maven自定义插件实现）
2.将classloder的内容进行base64编码后拆分内容寻找多个系统启动注入点写入到loader.key文件中（拆分时写入的路径和文件名需要进行base64加密避免全局搜索），例如
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private static void init() { String source = "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" ; String filePath = "" ; try { filePath = new String(Base64.decodeBase64( "dGVtcGZpbGVzL2R5bmFtaWNnZW5zZXJhdGUvbG9hZGVyLmtleQ==" ), "utf-8" ); } catch (Exception e){ e.printStackTrace(); } FileUtil.writeFile(filePath, source, true ); } |
3.通过GroovyClassLoader对classloder的内容（字符串）进行动态编译获取到对象，删除loader.key文件
pom文件增加动态编译依赖
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< dependency > < groupId >org.codehaus.groovy</ groupId > < artifactId >groovy-all</ artifactId > < version >2.4.13</ version > </ dependency > |
获取文件内容进行编译代码如下（写入/读取注意utf-8处理防止乱码）
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public class CustomCompile { private static Object Compile(String source){ Object instance = null ; try { // 编译器 CompilerConfiguration config = new CompilerConfiguration(); config.setSourceEncoding( "UTF-8" ); // 设置该GroovyClassLoader的父ClassLoader为当前线程的加载器(默认) GroovyClassLoader groovyClassLoader = new GroovyClassLoader(Thread.currentThread().getContextClassLoader(), config); Class<?> clazz = groovyClassLoader.parseClass(source); // 创建实例 instance = clazz.newInstance(); } catch (Exception e){ e.printStackTrace(); } return instance; } public static ClassLoader getClassLoader(){ String filePath = "tempfiles/dynamicgenserate/loader.key" ; String source = FileUtil.readFileContent(filePath); byte [] decodeByte = Base64.decodeBase64(source); String str = "" ; try { str = new String(decodeByte, "utf-8" ); } catch (Exception e){ e.printStackTrace(); } finally { FileUtil.deleteDirectory( "tempfiles/dynamicgenserate/" ); } return (ClassLoader)Compile(str); } } |
被保护class手动加壳
因为相关需要加密的class文件都是通过customerclassloder加载的，获取不到显示的class类型，所以我们实际的业务类只能通过反射的方法进行调用，例如业务工具类LicenseUtil，加密后类为LicenseCoreUtil，我们在LicenseUtil的方法中需要反射调用，LicenseCoreUtil中的方法，例如
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@Component public class LicenseUtil { private String coreClassName = "com.haopan.frame.core.util.LicenseCoreUtil" ; public String getMachineCode() throws Exception { return (String) CoreLoader.getInstance().executeMethod(coreClassName, "getMachineCode" ); } public boolean checkLicense( boolean startCheck) { return ( boolean )CoreLoader.getInstance().executeMethod(coreClassName, "checkLicense" ,startCheck); } } |
为了避免反射调用随着调用次数的增加损失较多的性能，使用了一个第三方的插件reflectasm，pom增加依赖
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< dependency > < groupId >com.esotericsoftware</ groupId > < artifactId >reflectasm</ artifactId > < version >1.11.0</ version > </ dependency > |
reflectasm使用了MethodAccess快速定位方法并在字节码层面进行调用，CoreLoader的代码如下
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public class CoreLoader { private ClassLoader classLoader; private CoreLoader() { classLoader = CustomCompile.getClassLoader(); } private static class SingleInstace { private static final CoreLoader instance = new CoreLoader(); } public static CoreLoader getInstance() { return SingleInstace.instance; } public Object executeMethod(String className,String methodName, Object... args) { Object result = null ; try { Class clz = classLoader.loadClass(className); MethodAccess access = MethodAccess.get(clz); result = access.invoke(clz.newInstance(), methodName, args); } catch (Exception e) { e.printStackTrace(); throw new ProtectClassLoadException( "executeMethod error" ); } return result; } } |
总结
自定义classloder并不是一个完美的代码加密保护的解决方案，但就改造工作量与对项目的影响程度来说是最小的，只需要针对关键核心逻辑方法进行保护，不会对系统运行逻辑产生影响制造bug，理论上来说只要classloder的拆分越小，系统启动注入点隐藏的越多，那破解的成本就会越高，如果有不足之处还请见谅
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原文链接：https://blog.csdn.net/u013407099/article/details/123021968
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