Android APK加壳技术

文章链接：http://blog.csdn.net/jiazhijun/article/details/8809542

 一、序言

        在上篇“Android APK加壳技术方案”（http://blog.csdn.net/jiazhijun/article/details/8678399）博文中，根据加壳数据在解壳程序Dex文件所处的位置，我提出了两种android Dex加壳技术实现方案，本片博文将对方案1代码实现进行讲解。博友可以根据方案1的代码实现原理对方案2自行实现。

       在方案1的代码实现过程中，各种不同的问题接踵出现，最初的方案也在不同问题的出现、解决过程中不断的得到调整、优化。

       本文的代码实现了对整个APK包的加壳处理。加壳程序不会对源程序有任何的影响。

二、代码实现

     本程序基于Android2.3代码实现，因为牵扯到系统代码的反射修改，本程序不保证在其它android版本正常工作，博友可以根据实现原理，自行实现对其它Android版本的兼容性开发。

     1、 加壳程序流程及代码实现

                  1、加密源程序APK为解壳数据

                  2、把解壳数据写入解壳程序DEX文件末尾，并在文件尾部添加解壳数据的大小。

                  3、修改解壳程序DEX头中checksum、signature 和file_size头信息。

       代码实现如下：

package com.android.dexshell;  import java.io.ByteArrayOutputStream;  import java.io.File;  import java.io.FileInputStream;  import java.io.FileOutputStream;  import java.io.IOException;  import java.security.MessageDigest;  import java.security.NoSuchAlgorithmException;  import java.util.zip.Adler32;    public class DexShellTool {      /**      * @param args      */      public static void main(String[] args) {          // TODO Auto-generated method stub          try {              File payloadSrcFile = new File("g:/payload.apk");              File unShellDexFile = new File("g:/unshell.dex");              byte[] payloadArray = encrpt(readFileBytes(payloadSrcFile));              byte[] unShellDexArray = readFileBytes(unShellDexFile);              int payloadLen = payloadArray.length;              int unShellDexLen = unShellDexArray.length;              int totalLen = payloadLen + unShellDexLen +4;              byte[] newdex = new byte[totalLen];              //添加解壳代码              System.arraycopy(unShellDexArray, 0, newdex, 0, unShellDexLen);              //添加加密后的解壳数据              System.arraycopy(payloadArray, 0, newdex, unShellDexLen,                      payloadLen);              //添加解壳数据长度              System.arraycopy(intToByte(payloadLen), 0, newdex, totalLen-4, 4);                          //修改DEX file size文件头              fixFileSizeHeader(newdex);              //修改DEX SHA1 文件头              fixSHA1Header(newdex);              //修改DEX CheckSum文件头              fixCheckSumHeader(newdex);                  String str = "g:/classes.dex";              File file = new File(str);              if (!file.exists()) {                  file.createNewFile();              }                            FileOutputStream localFileOutputStream = new FileOutputStream(str);              localFileOutputStream.write(newdex);              localFileOutputStream.flush();              localFileOutputStream.close();              } catch (Exception e) {              // TODO Auto-generated catch block              e.printStackTrace();          }      }            //直接返回数据，读者可以添加自己加密方法      private static byte[] encrpt(byte[] srcdata){          return srcdata;      }          private static void fixCheckSumHeader(byte[] dexBytes) {          Adler32 adler = new Adler32();          adler.update(dexBytes, 12, dexBytes.length - 12);          long value = adler.getValue();          int va = (int) value;          byte[] newcs = intToByte(va);          byte[] recs = new byte[4];          for (int i = 0; i < 4; i++) {              recs[i] = newcs[newcs.length - 1 - i];              System.out.println(Integer.toHexString(newcs[i]));          }          System.arraycopy(recs, 0, dexBytes, 8, 4);          System.out.println(Long.toHexString(value));          System.out.println();      }          public static byte[] intToByte(int number) {          byte[] b = new byte[4];          for (int i = 3; i >= 0; i--) {              b[i] = (byte) (number % 256);              number >>= 8;          }          return b;      }          private static void fixSHA1Header(byte[] dexBytes)              throws NoSuchAlgorithmException {          MessageDigest md = MessageDigest.getInstance("SHA-1");          md.update(dexBytes, 32, dexBytes.length - 32);          byte[] newdt = md.digest();          System.arraycopy(newdt, 0, dexBytes, 12, 20);          String hexstr = "";          for (int i = 0; i < newdt.length; i++) {              hexstr += Integer.toString((newdt[i] & 0xff) + 0x100, 16)                      .substring(1);          }          System.out.println(hexstr);      }          private static void fixFileSizeHeader(byte[] dexBytes) {              byte[] newfs = intToByte(dexBytes.length);          System.out.println(Integer.toHexString(dexBytes.length));          byte[] refs = new byte[4];          for (int i = 0; i < 4; i++) {              refs[i] = newfs[newfs.length - 1 - i];              System.out.println(Integer.toHexString(newfs[i]));          }          System.arraycopy(refs, 0, dexBytes, 32, 4);      }          private static byte[] readFileBytes(File file) throws IOException {          byte[] arrayOfByte = new byte[1024];          ByteArrayOutputStream localByteArrayOutputStream = new ByteArrayOutputStream();          FileInputStream fis = new FileInputStream(file);          while (true) {              int i = fis.read(arrayOfByte);              if (i != -1) {                  localByteArrayOutputStream.write(arrayOfByte, 0, i);              } else {                  return localByteArrayOutputStream.toByteArray();              }          }      }      }  

2、 解壳程序流程及代码实现

          在解壳程序的开发过程中需要解决如下几个关键的技术问题：

         （1）解壳代码如何能够第一时间执行？

                  Android程序由不同的组件构成，系统在有需要的时候启动程序组件。因此解壳程序必须在Android系统启动组件之前运行，完成对解壳数                据的解壳及APK文件的动态加载，否则会使程序出现加载类失败的异常。

                  Android开发者都知道Applicaiton做为整个应用的上下文，会被系统第一时间调用，这也是应用开发者程序代码的第一执行点。因此通过对              AndroidMainfest.xml的application的配置可以实现解壳代码第一时间运行。

<application      android:icon="@drawable/ic_launcher"      android:label="@string/app_name"      android:theme="@style/AppTheme" android:name="<span style="color: rgb(255, 0, 0);"><em><strong>com.android.dexunshell.ProxyApplication</strong></em></span>" >  </application>  

（2）如何替换回源程序原有的Application?

                  当在AndroidMainfest.xml文件配置为解壳代码的Application时。源程序原有的Applicaiton将被替换，为了不影响源程序代码逻辑，我们需要              在解壳代码运行完成后，替换回源程序原有的Application对象。我们通过在AndroidMainfest.xml文件中配置原有Applicaiton类信息来达到我们              的目的。解壳程序要在运行完毕后通过创建配置的Application对象，并通过反射修改回原Application。

<application      android:icon="@drawable/ic_launcher"      android:label="@string/app_name"      android:theme="@style/AppTheme" android:name="<em><strong><span style="color: rgb(255, 0, 0);">com.android.dexunshell.ProxyApplication</span></strong></em>" >      <span style="color: rgb(255, 0, 0);"><em><strong><meta-data android:name="APPLICATION_CLASS_NAME" android:value="com.***.Application"/></strong></em></span>  </application>  

 （3）如何通过DexClassLoader实现对apk代码的动态加载。

                  我们知道DexClassLoader加载的类是没有组件生命周期的，也就是说即使DexClassLoader通过对APK的动态加载完成了对组件类的加载，              当系统启动该组件时，还会出现加载类失败的异常。为什么组件类被动态加载入虚拟机，但系统却出现加载类失败呢？

                  通过查看Android源代码我们知道组件类的加载是由另一个ClassLoader来完成的，DexClassLoader和系统组件ClassLoader并不存在关                  系，系统组件ClassLoader当然找不到由DexClassLoader加载的类，如果把系统组件ClassLoader的parent修改成DexClassLoader，我们就可              以实现对apk代码的动态加载。

         （4）如何使解壳后的APK资源文件被代码动态引用。

                 代码默认引用的资源文件在最外层的解壳程序中，因此我们要增加系统的资源加载路径来实现对借壳后APK文件资源的加载。

        解壳实现代码：

package com.android.dexunshell;    import java.io.BufferedInputStream;  import java.io.ByteArrayInputStream;  import java.io.ByteArrayOutputStream;  import java.io.DataInputStream;  import java.io.File;  import java.io.FileInputStream;  import java.io.FileOutputStream;  import java.io.IOException;  import java.lang.ref.WeakReference;  import java.util.ArrayList;  import java.util.HashMap;  import java.util.Iterator;  import java.util.zip.ZipEntry;  import java.util.zip.ZipInputStream;    import dalvik.system.DexClassLoader;  import android.app.Application;  import android.content.pm.ApplicationInfo;  import android.content.pm.PackageManager;  import android.content.pm.PackageManager.NameNotFoundException;  import android.os.Bundle;  public class ProxyApplication extends Application {          private static final String appkey = "APPLICATION_CLASS_NAME";      private String apkFileName;      private String odexPath;      private String libPath;          protected void attachBaseContext(Context base) {          super.attachBaseContext(base);          try {              File odex = this.getDir("payload_odex", MODE_PRIVATE);              File libs = this.getDir("payload_lib", MODE_PRIVATE);              odexPath = odex.getAbsolutePath();              libPath = libs.getAbsolutePath();              apkFileName = odex.getAbsolutePath() + "/payload.apk";              File dexFile = new File(apkFileName);              if (!dexFile.exists())                  dexFile.createNewFile();              // 读取程序classes.dex文件              byte[] dexdata = this.readDexFileFromApk();              // 分离出解壳后的apk文件已用于动态加载              this.splitPayLoadFromDex(dexdata);              // 配置动态加载环境              Object currentActivityThread = RefInvoke.invokeStaticMethod(                      "android.app.ActivityThread", "currentActivityThread",                      new Class[] {}, new Object[] {});              String packageName = this.getPackageName();              HashMap mPackages = (HashMap) RefInvoke.getFieldOjbect(                      "android.app.ActivityThread", currentActivityThread,                      "mPackages");              WeakReference wr = (WeakReference) mPackages.get(packageName);              DexClassLoader dLoader = new DexClassLoader(apkFileName, odexPath,                      libPath, (ClassLoader) RefInvoke.getFieldOjbect(                              "android.app.LoadedApk", wr.get(), "mClassLoader"));              RefInvoke.setFieldOjbect("android.app.LoadedApk", "mClassLoader",                      wr.get(), dLoader);              } catch (Exception e) {              // TODO Auto-generated catch block              e.printStackTrace();          }      }          public void onCreate() {          {                  // 如果源应用配置有Appliction对象，则替换为源应用Applicaiton，以便不影响源程序逻辑。              String appClassName = null;              try {                  ApplicationInfo ai = this.getPackageManager()                          .getApplicationInfo(this.getPackageName(),                                  PackageManager.GET_META_DATA);                  Bundle bundle = ai.metaData;                  if (bundle != null                          && bundle.containsKey("APPLICATION_CLASS_NAME")) {                      appClassName = bundle.getString("APPLICATION_CLASS_NAME");                  } else {                      return;                  }              } catch (NameNotFoundException e) {                  // TODO Auto-generated catch block                  e.printStackTrace();              }                  Object currentActivityThread = RefInvoke.invokeStaticMethod(                      "android.app.ActivityThread", "currentActivityThread",                      new Class[] {}, new Object[] {});              Object mBoundApplication = RefInvoke.getFieldOjbect(                      "android.app.ActivityThread", currentActivityThread,                      "mBoundApplication");              Object loadedApkInfo = RefInvoke.getFieldOjbect(                      "android.app.ActivityThread$AppBindData",                      mBoundApplication, "info");              RefInvoke.setFieldOjbect("android.app.LoadedApk", "mApplication",                      loadedApkInfo, null);              Object oldApplication = RefInvoke.getFieldOjbect(                      "android.app.ActivityThread", currentActivityThread,                      "mInitialApplication");              ArrayList<Application> mAllApplications = (ArrayList<Application>) RefInvoke                      .getFieldOjbect("android.app.ActivityThread",                              currentActivityThread, "mAllApplications");              mAllApplications.remove(oldApplication);              ApplicationInfo appinfo_In_LoadedApk = (ApplicationInfo) RefInvoke                      .getFieldOjbect("android.app.LoadedApk", loadedApkInfo,                              "mApplicationInfo");              ApplicationInfo appinfo_In_AppBindData = (ApplicationInfo) RefInvoke                      .getFieldOjbect("android.app.ActivityThread$AppBindData",                              mBoundApplication, "appInfo");              appinfo_In_LoadedApk.className = appClassName;              appinfo_In_AppBindData.className = appClassName;              Application app = (Application) RefInvoke.invokeMethod(                      "android.app.LoadedApk", "makeApplication", loadedApkInfo,                      new Class[] { boolean.class, Instrumentation.class },                      new Object[] { false, null });              RefInvoke.setFieldOjbect("android.app.ActivityThread",                      "mInitialApplication", currentActivityThread, app);                  HashMap mProviderMap = (HashMap) RefInvoke.getFieldOjbect(                      "android.app.ActivityThread", currentActivityThread,                      "mProviderMap");              Iterator it = mProviderMap.values().iterator();              while (it.hasNext()) {                  Object providerClientRecord = it.next();                  Object localProvider = RefInvoke.getFieldOjbect(                          "android.app.ActivityThread$ProviderClientRecord",                          providerClientRecord, "mLocalProvider");                  RefInvoke.setFieldOjbect("android.content.ContentProvider",                          "mContext", localProvider, app);              }              app.onCreate();          }      }          private void splitPayLoadFromDex(byte[] data) throws IOException {          byte[] apkdata = decrypt(data);          int ablen = apkdata.length;          byte[] dexlen = new byte[4];          System.arraycopy(apkdata, ablen - 4, dexlen, 0, 4);          ByteArrayInputStream bais = new ByteArrayInputStream(dexlen);          DataInputStream in = new DataInputStream(bais);          int readInt = in.readInt();          System.out.println(Integer.toHexString(readInt));          byte[] newdex = new byte[readInt];          System.arraycopy(apkdata, ablen - 4 - readInt, newdex, 0, readInt);          File file = new File(apkFileName);          try {              FileOutputStream localFileOutputStream = new FileOutputStream(file);              localFileOutputStream.write(newdex);              localFileOutputStream.close();              } catch (IOException localIOException) {              throw new RuntimeException(localIOException);          }              ZipInputStream localZipInputStream = new ZipInputStream(                  new BufferedInputStream(new FileInputStream(file)));          while (true) {              ZipEntry localZipEntry = localZipInputStream.getNextEntry();              if (localZipEntry == null) {                  localZipInputStream.close();                  break;              }              String name = localZipEntry.getName();              if (name.startsWith("lib/") && name.endsWith(".so")) {                  File storeFile = new File(libPath + "/"                          + name.substring(name.lastIndexOf('/')));                  storeFile.createNewFile();                  FileOutputStream fos = new FileOutputStream(storeFile);                  byte[] arrayOfByte = new byte[1024];                  while (true) {                      int i = localZipInputStream.read(arrayOfByte);                      if (i == -1)                          break;                      fos.write(arrayOfByte, 0, i);                  }                  fos.flush();                  fos.close();              }              localZipInputStream.closeEntry();          }          localZipInputStream.close();          }          private byte[] readDexFileFromApk() throws IOException {          ByteArrayOutputStream dexByteArrayOutputStream = new ByteArrayOutputStream();          ZipInputStream localZipInputStream = new ZipInputStream(                  new BufferedInputStream(new FileInputStream(                          this.getApplicationInfo().sourceDir)));          while (true) {              ZipEntry localZipEntry = localZipInputStream.getNextEntry();              if (localZipEntry == null) {                  localZipInputStream.close();                  break;              }              if (localZipEntry.getName().equals("classes.dex")) {                  byte[] arrayOfByte = new byte[1024];                  while (true) {                      int i = localZipInputStream.read(arrayOfByte);                      if (i == -1)                          break;                      dexByteArrayOutputStream.write(arrayOfByte, 0, i);                  }              }              localZipInputStream.closeEntry();          }          localZipInputStream.close();          return dexByteArrayOutputStream.toByteArray();      }          // //直接返回数据，读者可以添加自己解密方法      private byte[] decrypt(byte[] data) {          return data;      }  

package com.android.dexunshell;    import java.io.BufferedInputStream;  import java.io.ByteArrayInputStream;  import java.io.ByteArrayOutputStream;  import java.io.DataInputStream;  import java.io.File;  import java.io.FileInputStream;  import java.io.FileOutputStream;  import java.io.IOException;  import java.lang.ref.WeakReference;  import java.util.ArrayList;  import java.util.HashMap;  import java.util.Iterator;  import java.util.zip.ZipEntry;  import java.util.zip.ZipInputStream;    import dalvik.system.DexClassLoader;  import android.app.Application;  import android.content.pm.ApplicationInfo;  import android.content.pm.PackageManager;  import android.content.pm.PackageManager.NameNotFoundException;  import android.os.Bundle;  public class ProxyApplication extends Application {      <span style="white-space:pre">  </span>private static final String appkey = "APPLICATION_CLASS_NAME";  <span style="white-space:pre">  </span>private String apkFileName;  <span style="white-space:pre">  </span>private String odexPath;  <span style="white-space:pre">  </span>private String libPath;      <span style="white-space:pre">  </span>protected void attachBaseContext(Context base) {  <span style="white-space:pre">      </span>super.attachBaseContext(base);  <span style="white-space:pre">      </span>try {  <span style="white-space:pre">          </span>File odex = this.getDir("payload_odex", MODE_PRIVATE);  <span style="white-space:pre">          </span>File libs = this.getDir("payload_lib", MODE_PRIVATE);  <span style="white-space:pre">          </span>odexPath = odex.getAbsolutePath();  <span style="white-space:pre">          </span>libPath = libs.getAbsolutePath();  <span style="white-space:pre">          </span>apkFileName = odex.getAbsolutePath() + "/payload.apk";  <span style="white-space:pre">          </span>File dexFile = new File(apkFileName);  <span style="white-space:pre">          </span>if (!dexFile.exists())  <span style="white-space:pre">              </span>dexFile.createNewFile();  <span style="white-space:pre">          </span>// 读取程序classes.dex文件  <span style="white-space:pre">          </span>byte[] dexdata = this.readDexFileFromApk();  <span style="white-space:pre">          </span>// 分离出解壳后的apk文件已用于动态加载  <span style="white-space:pre">          </span>this.splitPayLoadFromDex(dexdata);  <span style="white-space:pre">          </span>// 配置动态加载环境  <span style="white-space:pre">          </span>Object currentActivityThread = RefInvoke.invokeStaticMethod(  <span style="white-space:pre">                  </span>"android.app.ActivityThread", "currentActivityThread",  <span style="white-space:pre">                  </span>new Class[] {}, new Object[] {});  <span style="white-space:pre">          </span>String packageName = this.getPackageName();  <span style="white-space:pre">          </span>HashMap mPackages = (HashMap) RefInvoke.getFieldOjbect(  <span style="white-space:pre">                  </span>"android.app.ActivityThread", currentActivityThread,  <span style="white-space:pre">                  </span>"mPackages");  <span style="white-space:pre">          </span>WeakReference wr = (WeakReference) mPackages.get(packageName);  <span style="white-space:pre">          </span>DexClassLoader dLoader = new DexClassLoader(apkFileName, odexPath,  <span style="white-space:pre">                  </span>libPath, (ClassLoader) RefInvoke.getFieldOjbect(  <span style="white-space:pre">                          </span>"android.app.LoadedApk", wr.get(), "mClassLoader"));  <span style="white-space:pre">          </span>RefInvoke.setFieldOjbect("android.app.LoadedApk", "mClassLoader",  <span style="white-space:pre">                  </span>wr.get(), dLoader);      <span style="white-space:pre">      </span>} catch (Exception e) {  <span style="white-space:pre">          </span>// TODO Auto-generated catch block  <span style="white-space:pre">          </span>e.printStackTrace();  <span style="white-space:pre">      </span>}  <span style="white-space:pre">  </span>}      <span style="white-space:pre">  </span>public void onCreate() {  <span style="white-space:pre">      </span>{      <span style="white-space:pre">          </span>// 如果源应用配置有Appliction对象，则替换为源应用Applicaiton，以便不影响源程序逻辑。  <span style="white-space:pre">          </span>String appClassName = null;  <span style="white-space:pre">          </span>try {  <span style="white-space:pre">              </span>ApplicationInfo ai = this.getPackageManager()  <span style="white-space:pre">                      </span>.getApplicationInfo(this.getPackageName(),  <span style="white-space:pre">                              </span>PackageManager.GET_META_DATA);  <span style="white-space:pre">              </span>Bundle bundle = ai.metaData;  <span style="white-space:pre">              </span>if (bundle != null  <span style="white-space:pre">                      </span>&& bundle.containsKey("APPLICATION_CLASS_NAME")) {  <span style="white-space:pre">                  </span>appClassName = bundle.getString("APPLICATION_CLASS_NAME");  <span style="white-space:pre">              </span>} else {  <span style="white-space:pre">                  </span>return;  <span style="white-space:pre">              </span>}  <span style="white-space:pre">          </span>} catch (NameNotFoundException e) {  <span style="white-space:pre">              </span>// TODO Auto-generated catch block  <span style="white-space:pre">              </span>e.printStackTrace();  <span style="white-space:pre">          </span>}      <span style="white-space:pre">          </span>Object currentActivityThread = RefInvoke.invokeStaticMethod(  <span style="white-space:pre">                  </span>"android.app.ActivityThread", "currentActivityThread",  <span style="white-space:pre">                  </span>new Class[] {}, new Object[] {});  <span style="white-space:pre">          </span>Object mBoundApplication = RefInvoke.getFieldOjbect(  <span style="white-space:pre">                  </span>"android.app.ActivityThread", currentActivityThread,  <span style="white-space:pre">                  </span>"mBoundApplication");  <span style="white-space:pre">          </span>Object loadedApkInfo = RefInvoke.getFieldOjbect(  <span style="white-space:pre">                  </span>"android.app.ActivityThread$AppBindData",  <span style="white-space:pre">                  </span>mBoundApplication, "info");  <span style="white-space:pre">          </span>RefInvoke.setFieldOjbect("android.app.LoadedApk", "mApplication",  <span style="white-space:pre">                  </span>loadedApkInfo, null);  <span style="white-space:pre">          </span>Object oldApplication = RefInvoke.getFieldOjbect(  <span style="white-space:pre">                  </span>"android.app.ActivityThread", currentActivityThread,  <span style="white-space:pre">                  </span>"mInitialApplication");  <span style="white-space:pre">          </span>ArrayList<Application> mAllApplications = (ArrayList<Application>) RefInvoke  <span style="white-space:pre">                  </span>.getFieldOjbect("android.app.ActivityThread",  <span style="white-space:pre">                          </span>currentActivityThread, "mAllApplications");  <span style="white-space:pre">          </span>mAllApplications.remove(oldApplication);  <span style="white-space:pre">          </span>ApplicationInfo appinfo_In_LoadedApk = (ApplicationInfo) RefInvoke  <span style="white-space:pre">                  </span>.getFieldOjbect("android.app.LoadedApk", loadedApkInfo,  <span style="white-space:pre">                          </span>"mApplicationInfo");  <span style="white-space:pre">          </span>ApplicationInfo appinfo_In_AppBindData = (ApplicationInfo) RefInvoke  <span style="white-space:pre">                  </span>.getFieldOjbect("android.app.ActivityThread$AppBindData",  <span style="white-space:pre">                          </span>mBoundApplication, "appInfo");  <span style="white-space:pre">          </span>appinfo_In_LoadedApk.className = appClassName;  <span style="white-space:pre">          </span>appinfo_In_AppBindData.className = appClassName;  <span style="white-space:pre">          </span>Application app = (Application) RefInvoke.invokeMethod(  <span style="white-space:pre">                  </span>"android.app.LoadedApk", "makeApplication", loadedApkInfo,  <span style="white-space:pre">                  </span>new Class[] { boolean.class, Instrumentation.class },  <span style="white-space:pre">                  </span>new Object[] { false, null });  <span style="white-space:pre">          </span>RefInvoke.setFieldOjbect("android.app.ActivityThread",  <span style="white-space:pre">                  </span>"mInitialApplication", currentActivityThread, app);      <span style="white-space:pre">          </span>HashMap mProviderMap = (HashMap) RefInvoke.getFieldOjbect(  <span style="white-space:pre">                  </span>"android.app.ActivityThread", currentActivityThread,  <span style="white-space:pre">                  </span>"mProviderMap");  <span style="white-space:pre">          </span>Iterator it = mProviderMap.values().iterator();  <span style="white-space:pre">          </span>while (it.hasNext()) {  <span style="white-space:pre">              </span>Object providerClientRecord = it.next();  <span style="white-space:pre">              </span>Object localProvider = RefInvoke.getFieldOjbect(  <span style="white-space:pre">                      </span>"android.app.ActivityThread$ProviderClientRecord",  <span style="white-space:pre">                      </span>providerClientRecord, "mLocalProvider");  <span style="white-space:pre">              </span>RefInvoke.setFieldOjbect("android.content.ContentProvider",  <span style="white-space:pre">                      </span>"mContext", localProvider, app);  <span style="white-space:pre">          </span>}  <span style="white-space:pre">          </span>app.onCreate();  <span style="white-space:pre">      </span>}  <span style="white-space:pre">  </span>}      <span style="white-space:pre">  </span>private void splitPayLoadFromDex(byte[] data) throws IOException {  <span style="white-space:pre">      </span>byte[] apkdata = decrypt(data);  <span style="white-space:pre">      </span>int ablen = apkdata.length;  <span style="white-space:pre">      </span>byte[] dexlen = new byte[4];  <span style="white-space:pre">      </span>System.arraycopy(apkdata, ablen - 4, dexlen, 0, 4);  <span style="white-space:pre">      </span>ByteArrayInputStream bais = new ByteArrayInputStream(dexlen);  <span style="white-space:pre">      </span>DataInputStream in = new DataInputStream(bais);  <span style="white-space:pre">      </span>int readInt = in.readInt();  <span style="white-space:pre">      </span>System.out.println(Integer.toHexString(readInt));  <span style="white-space:pre">      </span>byte[] newdex = new byte[readInt];  <span style="white-space:pre">      </span>System.arraycopy(apkdata, ablen - 4 - readInt, newdex, 0, readInt);  <span style="white-space:pre">      </span>File file = new File(apkFileName);  <span style="white-space:pre">      </span>try {  <span style="white-space:pre">          </span>FileOutputStream localFileOutputStream = new FileOutputStream(file);  <span style="white-space:pre">          </span>localFileOutputStream.write(newdex);  <span style="white-space:pre">          </span>localFileOutputStream.close();      <span style="white-space:pre">      </span>} catch (IOException localIOException) {  <span style="white-space:pre">          </span>throw new RuntimeException(localIOException);  <span style="white-space:pre">      </span>}      <span style="white-space:pre">      </span>ZipInputStream localZipInputStream = new ZipInputStream(  <span style="white-space:pre">              </span>new BufferedInputStream(new FileInputStream(file)));  <span style="white-space:pre">      </span>while (true) {  <span style="white-space:pre">          </span>ZipEntry localZipEntry = localZipInputStream.getNextEntry();  <span style="white-space:pre">          </span>if (localZipEntry == null) {  <span style="white-space:pre">              </span>localZipInputStream.close();  <span style="white-space:pre">              </span>break;  <span style="white-space:pre">          </span>}  <span style="white-space:pre">          </span>String name = localZipEntry.getName();  <span style="white-space:pre">          </span>if (name.startsWith("lib/") && name.endsWith(".so")) {  <span style="white-space:pre">              </span>File storeFile = new File(libPath + "/"  <span style="white-space:pre">                      </span>+ name.substring(name.lastIndexOf('/')));  <span style="white-space:pre">              </span>storeFile.createNewFile();  <span style="white-space:pre">              </span>FileOutputStream fos = new FileOutputStream(storeFile);  <span style="white-space:pre">              </span>byte[] arrayOfByte = new byte[1024];  <span style="white-space:pre">              </span>while (true) {  <span style="white-space:pre">                  </span>int i = localZipInputStream.read(arrayOfByte);  <span style="white-space:pre">                  </span>if (i == -1)  <span style="white-space:pre">                      </span>break;  <span style="white-space:pre">                  </span>fos.write(arrayOfByte, 0, i);  <span style="white-space:pre">              </span>}  <span style="white-space:pre">              </span>fos.flush();  <span style="white-space:pre">              </span>fos.close();  <span style="white-space:pre">          </span>}  <span style="white-space:pre">          </span>localZipInputStream.closeEntry();  <span style="white-space:pre">      </span>}  <span style="white-space:pre">      </span>localZipInputStream.close();      <span style="white-space:pre">  </span>}      <span style="white-space:pre">  </span>private byte[] readDexFileFromApk() throws IOException {  <span style="white-space:pre">      </span>ByteArrayOutputStream dexByteArrayOutputStream = new ByteArrayOutputStream();  <span style="white-space:pre">      </span>ZipInputStream localZipInputStream = new ZipInputStream(  <span style="white-space:pre">              </span>new BufferedInputStream(new FileInputStream(  <span style="white-space:pre">                      </span>this.getApplicationInfo().sourceDir)));  <span style="white-space:pre">      </span>while (true) {  <span style="white-space:pre">          </span>ZipEntry localZipEntry = localZipInputStream.getNextEntry();  <span style="white-space:pre">          </span>if (localZipEntry == null) {  <span style="white-space:pre">              </span>localZipInputStream.close();  <span style="white-space:pre">              </span>break;  <span style="white-space:pre">          </span>}  <span style="white-space:pre">          </span>if (localZipEntry.getName().equals("classes.dex")) {  <span style="white-space:pre">              </span>byte[] arrayOfByte = new byte[1024];  <span style="white-space:pre">              </span>while (true) {  <span style="white-space:pre">                  </span>int i = localZipInputStream.read(arrayOfByte);  <span style="white-space:pre">                  </span>if (i == -1)  <span style="white-space:pre">                      </span>break;  <span style="white-space:pre">                  </span>dexByteArrayOutputStream.write(arrayOfByte, 0, i);  <span style="white-space:pre">              </span>}  <span style="white-space:pre">          </span>}  <span style="white-space:pre">          </span>localZipInputStream.closeEntry();  <span style="white-space:pre">      </span>}  <span style="white-space:pre">      </span>localZipInputStream.close();  <span style="white-space:pre">      </span>return dexByteArrayOutputStream.toByteArray();  <span style="white-space:pre">  </span>}      <span style="white-space:pre">  </span>// //直接返回数据，读者可以添加自己解密方法  <span style="white-space:pre">  </span>private byte[] decrypt(byte[] data) {  <span style="white-space:pre">      </span>return data;  <span style="white-space:pre">  </span>}  

 RefInvoke为反射调用工具类：

package com.android.dexunshell;    import java.lang.reflect.Field;  import java.lang.reflect.InvocationTargetException;  import java.lang.reflect.Method;    public class RefInvoke {            public static  Object invokeStaticMethod(String class_name, String method_name, Class[] pareTyple, Object[] pareVaules){                    try {              Class obj_class = Class.forName(class_name);              Method method = obj_class.getMethod(method_name,pareTyple);              return method.invoke(null, pareVaules);          } catch (SecurityException e) {              // TODO Auto-generated catch block              e.printStackTrace();          }  catch (IllegalArgumentException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (IllegalAccessException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (NoSuchMethodException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (InvocationTargetException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (ClassNotFoundException e) {              // TODO Auto-generated catch block              e.printStackTrace();          }          return null;                }            public static  Object invokeMethod(String class_name, String method_name, Object obj ,Class[] pareTyple, Object[] pareVaules){                    try {              Class obj_class = Class.forName(class_name);              Method method = obj_class.getMethod(method_name,pareTyple);              return method.invoke(obj, pareVaules);          } catch (SecurityException e) {              // TODO Auto-generated catch block              e.printStackTrace();          }  catch (IllegalArgumentException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (IllegalAccessException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (NoSuchMethodException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (InvocationTargetException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (ClassNotFoundException e) {              // TODO Auto-generated catch block              e.printStackTrace();          }          return null;                }            public static Object getFieldOjbect(String class_name,Object obj, String filedName){          try {              Class obj_class = Class.forName(class_name);              Field field = obj_class.getDeclaredField(filedName);              field.setAccessible(true);              return field.get(obj);          } catch (SecurityException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (NoSuchFieldException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (IllegalArgumentException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (IllegalAccessException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (ClassNotFoundException e) {              // TODO Auto-generated catch block              e.printStackTrace();          }          return null;                }            public static Object getStaticFieldOjbect(String class_name, String filedName){                    try {              Class obj_class = Class.forName(class_name);              Field field = obj_class.getDeclaredField(filedName);              field.setAccessible(true);              return field.get(null);          } catch (SecurityException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (NoSuchFieldException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (IllegalArgumentException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (IllegalAccessException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (ClassNotFoundException e) {              // TODO Auto-generated catch block              e.printStackTrace();          }          return null;                }            public static void setFieldOjbect(String classname, String filedName, Object obj, Object filedVaule){          try {              Class obj_class = Class.forName(classname);              Field field = obj_class.getDeclaredField(filedName);              field.setAccessible(true);              field.set(obj, filedVaule);          } catch (SecurityException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (NoSuchFieldException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (IllegalArgumentException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (IllegalAccessException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (ClassNotFoundException e) {              // TODO Auto-generated catch block              e.printStackTrace();          }         }            public static void setStaticOjbect(String class_name, String filedName, Object filedVaule){          try {              Class obj_class = Class.forName(class_name);              Field field = obj_class.getDeclaredField(filedName);              field.setAccessible(true);              field.set(null, filedVaule);          } catch (SecurityException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (NoSuchFieldException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (IllegalArgumentException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (IllegalAccessException e) {              // TODO Auto-generated catch block              e.printStackTrace();          } catch (ClassNotFoundException e) {              // TODO Auto-generated catch block              e.printStackTrace();          }             }    }  

三、总结

       本文代码基本实现了APK文件的加壳及脱壳原理，该代码作为实验代码还有诸多地方需要改进。比如：

             1、加壳数据的加密算法的添加。

             2、脱壳代码由Java语言实现，可通过C代码的实现对脱壳逻辑进行保护，以达到更好的反逆向分析效果。