Android安全讲座第六层 [二] APK加壳技术方案

本文章由Jack_Jia编写，转载请注明出处。

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

作者：Jack_Jia   邮箱： 309zhijun@163.com

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;
publicclass DexShellTool {
/**
     * @param args
     */
publicstaticvoid 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 = newbyte[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
privatestaticbyte[] encrpt(byte[] srcdata){
return srcdata;
    }
privatestaticvoid 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 = newbyte[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();
    }
publicstaticbyte[] intToByte(int number) {
byte[] b = newbyte[4];
for (int i = 3; i >= 0; i--) {
            b[i] = (byte) (number % 256);
            number >>= 8;
        }
return b;
    }
privatestaticvoid 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);
    }
privatestaticvoid fixFileSizeHeader(byte[] dexBytes) {
byte[] newfs = intToByte(dexBytes.length);
        System.out.println(Integer.toHexString(dexBytes.length));
byte[] refs = newbyte[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);
    }
privatestaticbyte[] readFileBytes(File file) throws IOException {
byte[] arrayOfByte = newbyte[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>" >
<spanstyle="color: rgb(255, 0, 0);"><em><strong><meta-dataandroid: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;
publicclass ProxyApplication extends Application {
privatestaticfinal String appkey = "APPLICATION_CLASS_NAME";
private String apkFileName;
private String odexPath;
private String libPath;
protectedvoid 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();
        }
    }
publicvoid 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();
        }
    }
privatevoid splitPayLoadFromDex(byte[] data) throws IOException {
byte[] apkdata = decrypt(data);
int ablen = apkdata.length;
byte[] dexlen = newbyte[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 = newbyte[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) {
thrownew 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 = newbyte[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();
    }
privatebyte[] 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 = newbyte[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
privatebyte[] 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;
publicclass ProxyApplication extends Application {
<span style="white-space:pre">  </span>privatestaticfinal 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>protectedvoid 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>publicvoid 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>privatevoid 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 = newbyte[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 = newbyte[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>thrownew 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 = newbyte[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>privatebyte[] 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 = newbyte[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>privatebyte[] 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;
publicclass RefInvoke {
publicstatic  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();
        }
returnnull;
    }
publicstatic  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();
        }
returnnull;
    }
publicstatic 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();
        }
returnnull;
    }
publicstatic 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();
        }
returnnull;
    }
publicstaticvoid 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();
        }
    }
publicstaticvoid 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。