自定义classloader加密java程序

tiantian911

大概想法是这样的：
1. 生成密钥用于在des算法中加密。
2. classloader类中动态的解密class，并且通过反射机制执行main方法。
3. 对classloader类进行高质量的混淆。

首先需要生成des算法中的key：

import java.io.File;import java.io.FileOutputStream;import java.security.SecureRandom;import javax.crypto.KeyGenerator;import javax.crypto.SecretKey;class Key {private String keyName;public Key() {}public Key(String keyName) {this.keyName = keyName;}public void createKey(String keyName) throws Exception {SecureRandom sr = new SecureRandom();KeyGenerator kg = KeyGenerator.getInstance("DES");kg.init(sr);SecretKey key = kg.generateKey();System.out.println(key.toString());byte rawKeyData[] = key.getEncoded();FileOutputStream fo = new FileOutputStream(new File(keyName));fo.write(rawKeyData);fo.close();}public static void main(String args[]) {try {new Key("").createKey("d:/key.txt");} catch (Exception e) {e.printStackTrace();}}}

有了key之后就可以对class进行加密了：
package com.hitachi.crypt;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.security.SecureRandom;import javax.crypto.Cipher;import javax.crypto.SecretKey;import javax.crypto.SecretKeyFactory;import javax.crypto.spec.DESKeySpec;public class Crypt {    public static void main(String[] args) throws Exception {        SecureRandom sr = new SecureRandom();        FileInputStream fi = new FileInputStream(new File("d:/key.txt"));        byte rawKeyData[] = new byte[fi.available()];        fi.read(rawKeyData);        fi.close();        DESKeySpec dks = new DESKeySpec(rawKeyData);        SecretKey key = SecretKeyFactory.getInstance("DES").generateSecret(dks);        Cipher cipher = Cipher.getInstance("DES");        cipher.init(Cipher.ENCRYPT_MODE, key, sr);        FileInputStream fi2 = new FileInputStream(new File("d:/HelloWorld.class"));        byte data[] = new byte[fi2.available()];        fi2.read(data);        fi2.close();        byte encryptedData[] = cipher.doFinal(data);        FileOutputStream fo = new FileOutputStream(new File("d:/HelloWorld.class"));        fo.write(encryptedData);        fo.close();    }}
然后还是关键的classloader类：
package com.hitachi.classloader;import java.io.File;import java.io.FileInputStream;import java.io.IOException;import java.util.Hashtable;import java.util.jar.JarEntry;import java.util.jar.JarInputStream;public class MyClassLoader extends ClassLoader {private static String myClasspath = new String("");private static Hashtable<String, Class<?>> loadClassHashTable = new Hashtable<String, Class<?>>();private static Hashtable<String, Long> loadClassTime = new Hashtable<String, Long>();public MyClassLoader() {}/** *//** * create a classloader and specify a classpath. *  * @param myClasspath *            the specified classpath name. */public MyClassLoader(String myClasspath) {if (!myClasspath.endsWith("\\")) {myClasspath = myClasspath + "\\";}MyClassLoader.myClasspath = myClasspath;}/** *//** * set the classpath *  * @param myClasspath *            the specified classpath name */public void SetmyClasspath(String myClasspath) {if (!myClasspath.endsWith("\\")) {myClasspath = myClasspath + "\\";}MyClassLoader.myClasspath = myClasspath;}/** *//** * Loads the class with the specified binary name. This method searches for * classes in the same manner as the loadClass(String, boolean) method. * Invoking this method is equivalent to invoking {loadClass(name,false)}. *  * @param className *            The binary name of the class. *  * @return The resulting <tt>Class</tt> object. *  * @throws ClassNotFoundException *             If the class was not found. */@SuppressWarnings("unchecked")public Class loadClass(String className) throws ClassNotFoundException {return loadClass(className, false);}/** *//** * Loads the class with the specified binary name. The default * implementation of this method searches for classes in the following * order: *  * Invoke {findLoadedClass(String)} to check if the class has already been * loaded. *  * Invoke {findSystemClass(String)} to load the system class. *  * Invoke the {findClass(String)} method to find the class. *  * If the class was found using the above steps, and the resolve flag is * true, this method will then invoke the {resolveClass(Class)} method on * the resulting Class object. *  * @param name *            The binary name of the class. *  * @param resolve *            If true then resolve the class. *  * @return The resulting Class object. *  * @throws ClassNotFoundException *             If the class could not be found. */@SuppressWarnings("unchecked")protected Class loadClass(String name, boolean resolve)throws ClassNotFoundException {try {Class foundClass = findLoadedClass(name);// check if the class has already been loaded.if (foundClass != null) {System.out.println("Complete to load the class: " + name);return foundClass;}// if the class is systemClass, load the system class by systemif (name.startsWith("java.")) {foundClass = findSystemClass(name);loadClassHashTable.put(name, foundClass);System.out.println("System is loading the class: " + name);return foundClass;}// invoke the findClass() method to load the classtry {foundClass = findClass(name);} catch (Exception fnfe) {}if (resolve && (foundClass != null)) {resolveClass(foundClass);}return foundClass;} catch (Exception e) {throw new ClassNotFoundException(e.toString());}}/** *//** * Finds the class with the specified binary name.The default implementation * throws a ClassNotFoundException. *  * @param className *            The binary name of the class. *  * @return The resulting Class object. *  * @throws ClassNotFoundException *             If the class could not be found. */@SuppressWarnings("unchecked")public Class findClass(String className) {byte[] classData = null;try {classData = loadClassData(className);} catch (IOException e) {e.printStackTrace();}if (classData == null) {return null;}System.out.println("MyClassLoader is loading : " + className + "");Class c = defineClass(className, classData, 0, classData.length);MyClassLoader.loadClassHashTable.put(className, c);System.out.println("Complete to load the class :" + className);return c;}/** *//** * Loads the classData with the specified binary name. This method searches * for classes in the specified classpath as * searchFile(myClasspath,className) method. *  * @param name *            The binary name of the class *  * @return The resulting the classData of the class object by byte[] *  * @throws IOException *             if have some failed or interrupted I/O operations. */private byte[] loadClassData(String className) throws IOException {String filePath = searchFile(myClasspath, className + ".class");if (!(filePath == null || filePath == "")) {System.out.println("It have found the file : " + className+ ".  Begin to read the data and load the class。");FileInputStream inFile = new FileInputStream(filePath);byte[] classData = new byte[inFile.available()];inFile.read(classData);inFile.close();loadClassTime.put(className, new File(filePath).lastModified());return classData;} else {filePath = searchFile(myClasspath, className + ".java");if (!(filePath == null || filePath == "")) {System.out.println("It have found the file : " + filePath+ ".  Begin to translate");Runtime.getRuntime().exec("javac " + filePath);try {Thread.sleep(1000);} catch (InterruptedException e) {e.printStackTrace();}System.out.println("Translate it over : " + filePath);return loadClassData(className);} else {System.out.println("Haven't found the file， and fail to read the classData！");return null;}}}/** *//** * Loads the class with the specified binary name.The default implementation * throws a ClassNotFoundException. *  * @param classData *            The data of the class. * @param className *            The binary name of the class. *  * @return The resulting Class object. *  * @throws ClassNotFoundException *             If the class could not be found. */public Class loadClass(byte[] classData, String className)throws ClassNotFoundException {System.out.println("MyClassLoader is loading : " + className + "");Class c = defineClass(className, classData, 0, classData.length);loadClassHashTable.put(className, c);System.out.println("Complete to load the class :" + className);return c;}/** *//** * Loads the class with the specified binary name.The default implementation * throws a ClassNotFoundException. *  * @param className *            The binary name of the class. * @param jarName *            The binary name of the jar that search the class from it. *  * @return The resulting Class object. *  * @throws ClassNotFoundException *             If the class could not be found. */protected Class loadClass(String className, String jarName)throws ClassNotFoundException {String jarPath = searchFile(myClasspath, jarName + ".jar");JarInputStream in = null;if (!(jarPath == null || jarPath == "")) {try {in = new JarInputStream(new FileInputStream(jarPath));JarEntry entry;while ((entry = in.getNextJarEntry()) != null) {String outFileName = entry.getName().substring(entry.getName().lastIndexOf("/") + 1,entry.getName().length());if (outFileName.equals(className + ".class")) {if (entry.getSize() == -1) {System.err.println("error ： can't read the file！");return null;}byte[] classData = new byte[(int) entry.getSize()];System.out.println("It have found the file : "+ className+ ".  Begin to read the data and load the class。");in.read(classData);return loadClass(classData, className);}}System.out.println("Haven't found the file " + className+ " in " + jarName + ".jar.");} catch (IOException e) {e.printStackTrace();} finally {try {in.close();} catch (IOException e) {e.printStackTrace();}}} else {System.out.println("Haven't found the jarFile: " + jarName+ ".jar.");return null;}return null;}/** *//** * Reloads the class with the specified binary name. Needn't have to restart * JVM then reload the class. *  * @param className *            The binary name of the class need to reload . *  * @return The resulting Class object. *  * @throws ClassNotFoundException *             If the class was not found. */public Class reload(String fileName) {String filePath = searchFile(myClasspath, fileName + ".class");Long a = new File(filePath).lastModified();if (!a.equals(loadClassTime.get(fileName))) {loadClassHashTable.remove(fileName);loadClassTime.remove(fileName);try {MyClassLoader mc2 = new MyClassLoader(myClasspath);mc2.loadClass(fileName);} catch (ClassNotFoundException e) {e.printStackTrace();}} else {System.out.println("The class is the newest version , needn't reloading.");}return null;}/** *//** * search the file with the specified binary name. Needn't have to restart * JVM then reload the class. *  * @param classpath *            the specified path where we search. * @param fileName *            The binary name of the file that want to search. *  * @return The resulting file path. */public String searchFile(String classpath, String fileName) {String cut = fileName.substring(fileName.lastIndexOf('.'), fileName.length());String path = fileName.substring(0, fileName.lastIndexOf('.')).replace('.', '/')+ cut;File f = new File(classpath + path);if (f.isFile()) {return f.getPath();} else {String objects[] = new File(classpath).list();for (int i = 0; i < objects.length; i++) {if (new File(classpath + File.separator + objects[i]).isDirectory()) {String s = searchFile(classpath + objects[i]+ File.separator, fileName);if (s == null || s == "") {continue;} else {return s;}}}}return null;};}


最后解密，并且通过反射机制执行：
package com.hitachi.crypt;import java.io.File;import java.io.FileInputStream;import java.lang.reflect.Method;import java.security.SecureRandom;import javax.crypto.Cipher;import javax.crypto.SecretKey;import javax.crypto.SecretKeyFactory;import javax.crypto.spec.DESKeySpec;import com.hitachi.classloader.MyClassLoader;public class Decrypt {public static void main(String[] args) throws Exception {SecureRandom sr = new SecureRandom();FileInputStream fi = new FileInputStream(new File("d:/key.txt"));byte rawKeyData[] = new byte[fi.available()];fi.read(rawKeyData);fi.close();DESKeySpec dks = new DESKeySpec(rawKeyData);SecretKey key = SecretKeyFactory.getInstance("DES").generateSecret(dks);Cipher cipher = Cipher.getInstance("DES");cipher.init(Cipher.DECRYPT_MODE, key, sr);FileInputStream fi2 = new FileInputStream(new File("D:/HelloWorld.class"));byte encryptedData[] = new byte[fi2.available()];fi2.read(encryptedData);fi2.close();byte decryptedData[] = cipher.doFinal(encryptedData);MyClassLoader mcl = new MyClassLoader("D:/");Class cl = mcl.loadClass(decryptedData, "HelloWorld");Method mainMethod = cl.getMethod("sayHello");mainMethod.invoke(null, null);}}

其中源文件是这样的：

public class HelloWorld {/** * @param args */public static void main(String[] args) {// TODO Auto-generated method stubSystem.out.println("Hello world");}public static void sayHello() {System.out.println("Hello");}}

就可以了。