解密實例Crackme0201----分析APK檔案 - Android 台灣中文網

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2016-3-28 10:22 上傳

開始分析：

當程式執行錯誤時：會彈出，無效的用戶名稱或註冊碼，以此線索來尋找關鍵代碼。開啟"resvaluesstring.xml"檔案：

<?xml version="1.0" encoding="UTF-8"?>
-<resources>
<string name="app_name">Crackme0201</string>
<string name="menu_settings">Settings</string>
<string name="title_activity_main">Crackme0201</string>
<string name="info">Android程式破解演示實例</string>
<string name="username">用戶名稱：</string>
<string name="sn">註冊碼：</string>
<string name="register">注冊</string>
<string name="hint_username">請輸入用戶名稱</string>
<string name="hint_sn">請輸入16位的註冊碼</string>
<string name="unregister">程式未註冊</string>
<string name="registered">程式已註冊</string>
<string name="unsuccessed">無效用戶名稱或註冊碼</string>
<string name="successed">恭喜您！註冊成功</string>
</resources>

複製代碼

string.xml中的字符串資源在"gen/<packagename>/R.java"檔案中的string類中被標識，每一個字符串都有唯一的Int類型索引值，apktool反編譯之後，所有索引值在public.xml檔案中。

<?xml version="1.0" encoding="UTF-8"?>
-<resources>
<public id="0x7f020001" name="ic_launcher" type="drawable"/>
<public id="0x7f020000" name="ic_action_search" type="drawable"/>
<public id="0x7f030000" name="activity_main" type="layout"/>
<public id="0x7f040000" name="padding_small" type="dimen"/>
<public id="0x7f040001" name="padding_medium" type="dimen"/>
<public id="0x7f040002" name="padding_large" type="dimen"/>
<public id="0x7f050000" name="app_name" type="string"/>
<public id="0x7f050001" name="menu_settings" type="string"/>
<public id="0x7f050002" name="title_activity_main" type="string"/>
<public id="0x7f050003" name="info" type="string"/>
<public id="0x7f050004" name="username" type="string"/>
<public id="0x7f050005" name="sn" type="string"/>
<public id="0x7f050006" name="register" type="string"/>
<public id="0x7f050007" name="hint_username" type="string"/>
<public id="0x7f050008" name="hint_sn" type="string"/>
<public id="0x7f050009" name="unregister" type="string"/>
<public id="0x7f05000a" name="registered" type="string"/>
<public id="0x7f05000b" name="unsuccessed" type="string"/>
<public id="0x7f05000c" name="successed" type="string"/>
<public id="0x7f060000" name="AppTheme" type="style"/>
<public id="0x7f070000" name="activity_main" type="menu"/>
<public id="0x7f080000" name="textView1" type="id"/>
<public id="0x7f080001" name="edit_username" type="id"/>
<public id="0x7f080002" name="edit_sn" type="id"/>
<public id="0x7f080003" name="button_register" type="id"/>
<public id="0x7f080004" name="menu_settings" type="id"/>
</resources>

複製代碼

可知：unsuccessed的值為0x7f05000b;

接下來在smali目錄中搜尋含有內容為0X7F05000b的檔案：【註：在檔案下面的組織裡面的--資料夾和搜尋選項中--搜尋---始終搜尋檔案名和內容】即可搜尋。（有點問題，有時候搜不出來。正在鑽研中。）

最後發現：只有MainActivity$1.smali檔案一處被調用。

.class Lcom/droider/crackme0201/MainActivity$1;
.super Ljava/lang/Object;
.source "MainActivity.java"
# interfaces
.implements Landroid/view/View$OnClickListener;
# annotations
.annotation system Ldalvik/annotation/EnclosingMethod;
value = Lcom/droider/crackme0201/MainActivity;->onCreate(Landroid/os/Bundle;)V
.end annotation
.annotation system Ldalvik/annotation/InnerClass;
accessFlags = 0x0
name = null
.end annotation
# instance fields
.field final synthetic this$0:Lcom/droider/crackme0201/MainActivity;
# direct methods
.method constructor <init>(Lcom/droider/crackme0201/MainActivity;)V
.locals 0
.parameter
.prologue
.line 1
iput-object p1, p0, Lcom/droider/crackme0201/MainActivity$1;->this$0:Lcom/droider/crackme0201/MainActivity;
.line 29
invoke-direct {p0}, Ljava/lang/Object;-><init>()V
return-void
.end method
# virtual methods
.method public onClick(Landroid/view/View;)V
.locals 4
.parameter "v"
.prologue
const/4 v3, 0x0
.line 32
iget-object v0, p0, Lcom/droider/crackme0201/MainActivity$1;->this$0:Lcom/droider/crackme0201/MainActivity;
iget-object v1, p0, Lcom/droider/crackme0201/MainActivity$1;->this$0:Lcom/droider/crackme0201/MainActivity;
#getter for: Lcom/droider/crackme0201/MainActivity;->edit_userName:Landroid/widget/EditText;
invoke-static {v1}, Lcom/droider/crackme0201/MainActivity;->access$0(Lcom/droider/crackme0201/MainActivity;)Landroid/widget/EditText;
move-result-object v1
invoke-virtual {v1}, Landroid/widget/EditText;->getText()Landroid/text/Editable;
move-result-object v1
invoke-interface {v1}, Landroid/text/Editable;->toString()Ljava/lang/String;
move-result-object v1
invoke-virtual {v1}, Ljava/lang/String;->trim()Ljava/lang/String;
move-result-object v1
.line 33
iget-object v2, p0, Lcom/droider/crackme0201/MainActivity$1;->this$0:Lcom/droider/crackme0201/MainActivity;
#getter for: Lcom/droider/crackme0201/MainActivity;->edit_sn:Landroid/widget/EditText;
invoke-static {v2}, Lcom/droider/crackme0201/MainActivity;->access$1(Lcom/droider/crackme0201/MainActivity;)Landroid/widget/EditText;
move-result-object v2
invoke-virtual {v2}, Landroid/widget/EditText;->getText()Landroid/text/Editable;
move-result-object v2
invoke-interface {v2}, Landroid/text/Editable;->toString()Ljava/lang/String;
move-result-object v2
invoke-virtual {v2}, Ljava/lang/String;->trim()Ljava/lang/String;
move-result-object v2
.line 32
#calls: Lcom/droider/crackme0201/MainActivity;->checkSN(Ljava/lang/String;Ljava/lang/String;)Z
invoke-static {v0, v1, v2}, Lcom/droider/crackme0201/MainActivity;->access$2(Lcom/droider/crackme0201/MainActivity;Ljava/lang/String;Ljava/lang/String;)Z
move-result v0
.line 33
if-nez v0, :cond_0 #如果結果不為0，則跳轉到cond_0處。
.line 34
iget-object v0, p0, Lcom/droider/crackme0201/MainActivity$1;->this$0:Lcom/droider/crackme0201/MainActivity;
.line 35
const v1, 0x7f05000b
.line 34
invoke-static {v0, v1, v3}, Landroid/widget/Toast;->makeText(Landroid/content/Context;II)Landroid/widget/Toast;
move-result-object v0
.line 35
invoke-virtual {v0}, Landroid/widget/Toast;->show()V
.line 42
:goto_0
return-void
.line 37
:cond_0
iget-object v0, p0, Lcom/droider/crackme0201/MainActivity$1;->this$0:Lcom/droider/crackme0201/MainActivity;
#使用iget-object指令獲取MainActivity實例的引用。
.line 38
const v1, 0x7f05000c
.line 37
invoke-static {v0, v1, v3}, Landroid/widget/Toast;->makeText(Landroid/content/Context;II)Landroid/widget/Toast;
move-result-object v0
.line 38
invoke-virtual {v0}, Landroid/widget/Toast;->show()V
.line 39
iget-object v0, p0, Lcom/droider/crackme0201/MainActivity$1;->this$0:Lcom/droider/crackme0201/MainActivity;
#getter for: Lcom/droider/crackme0201/MainActivity;->btn_register:Landroid/widget/Button;
invoke-static {v0}, Lcom/droider/crackme0201/MainActivity;->access$3(Lcom/droider/crackme0201/MainActivity;)Landroid/widget/Button;
move-result-object v0
invoke-virtual {v0, v3}, Landroid/widget/Button;->setEnabled(Z)V
.line 40
iget-object v0, p0, Lcom/droider/crackme0201/MainActivity$1;->this$0:Lcom/droider/crackme0201/MainActivity;
const v1, 0x7f05000a
invoke-virtual {v0, v1}, Lcom/droider/crackme0201/MainActivity;->setTitle(I)V
goto :goto_0
.end method

複製代碼

修改Smali檔案代碼：

if-nez v0, :cond_0 #如果結果不為0，則跳轉到cond_0處。修改為:
if-eqz v0, :cond_0 #如果結果為0或等於0，則跳轉到cond_0處。
然後對修改後的檔案進行重新編譯打包成apk檔案。

在cmd中輸入：apktool b outdir

編譯生成的apk沒有簽名，還不能安裝測試。接下裡需要用signapk.jar工具對apk檔案進行簽名。

安裝測試：

由於AVD太慢，所以在手機設備上執行；轉換成手機模式：window---OpenPerspective---DDOS,雙擊即可。
在命令行下：adb install signed.apk

安裝完後，隨便輸入註冊碼，就會出現：恭喜您，註冊成功字樣！

作者: betty740827 時間: 2016-4-4 06:13
看不懂@@

作者: police4 時間: 2016-4-19 20:54
受益良多,繼續加油!!

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