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DevQuiz 2011 の模範解答 Android編
1. The document discusses decompiling an Android APK file into smali code using apktool and analyzing the smali code to understand the logic of the original Java code. 2. It shows how to decompile an APK, find the relevant smali files, and start translating smali instructions and structures back into equivalent Java code. 3. Useful resources mentioned for learning more about the Dalvik bytecode, smali syntax, and decompiling process include websites on Dalvik opcodes, the JUMPERZ blog, and the CodeGenerator source code.
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DevQuiz 2011 の模範解答 Android編
- 1. DevQuiz Android 2011/10/01 Open at Xi for Developer
- 2. • YAMAZAKI Makoto(twitter: @zaki50) 4988/5000 • Android • • StickyShortcut • ClaudiaVoice for Android • Java ( ) • GDD 2011 Japan ADK OpenCall
- 3. DevQuiz • Google DeveloperDay 2011 Japan
- 4. Android • AIDL Android AIDL package com.google.android.apps.gddquiz; interface IQuizService { String getCode(); }
- 5. 1 1. 2. 3. AIDL
- 6. 1 1. 2. 3. AIDL
- 7.
- 8. • apk • smali (dalvik assembler) • Java
- 9. Step 1 apk •apk zip smali apktool http://goo.gl/5U8U $ apktool d DevQuiz11Service_r1.apk I: Baksmaling... I: Loading resource table... I: Loaded. I: Loading resource table from file: /Users/zaki/apktool/framework/1.apk I: Loaded. I: Decoding file-resources... I: Decoding values*/* XMLs... I: Done. I: Copying assets and libs... $ ls DevQuiz11Service_r1 AndroidManifest.xml apktool.yml res smali
- 10. smali • Dalvik .classpublic Lcom/google/android/apps/gddquiz/gddquiz11service/DevQuiz11Service; .super Landroid/app/Service; .method static synthetic a(Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String; .locals 1 invoke-static {p0, p1}, Lcom/google/android/apps/gddquiz/gddquiz11service/ DevQuiz11Service;->b(Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String; move-result-object v0 return-object v0 .end method • http://pallergabor.uw.hu/androidblog/dalvik_opcodes.html
- 11. Step 2 • ProGuard • Service $ cd DevQuiz11Service_r1/smali $ grep -rl ".super Landroid/app/Service" . ./com/google/android/apps/gddquiz/gddquiz11service/DevQuiz11Service.smali $ cat DevQuiz11Service.smali ( ) .method private static b(Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String; .locals 6 ( ) const-string v2, "SHA-1" invoke-static {v2}, Ljava/security/MessageDigest;->getInstance(Ljava/lang/String;)Ljava/security/MessageDigest; ( )
- 12. Step 2 • DevQuiz11Service#b private DevQuiz11Service#a • DevQuiz11Service#a $ grep -rl DevQuiz11Service . ./gddquiz11service/a.smali ./gddquiz11service/DevQuiz11Service.smali ./gddquiz11service/DevQuiz11ServiceActivity.smali
- 13. Step 3 Java • .method private static b(Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String; .locals 6 private static String getCode(String googleAccount, String passcode) { // googleAccount: p0, passcode: p1 // v0 v5 • static invoke-virtual {p0}, Ljava/lang/String;->trim()Ljava/lang/String; move-result-object v0 String v0 = googleAccount.trim(); • const-string v2, "SHA-1" invoke-static {v2}, Ljava/security/MessageDigest;->getInstance(Ljava/lang/String;)Ljava/security/ MessageDigest; move-result-object v2 MessageDigest v2 = MessageDigest.getInstance(“SHA-1”);
- 14. Step 3 Java • new-instance v3, Ljava/lang/StringBuilder; move-result-object v0 invoke-direct {v3, v0}, Ljava/lang/StringBuilder;-><init>(Ljava/lang/String;)V StringBuilder v3 = new StringBuilder(v0); • if-lt v2, v3, :cond_0 if (v2 < v3) goto cond_0; // goto if-ne v3, v4, :cond_1 if (v3 != v4) goto cond_1; // goto • xor xor-int/2addr v3, v4 v3 ^= v4;
- 15. Step 3 Java • → http://goo.gl/78W6s CodeGenerator.java
- 16.
- 17. • apktook http://goo.gl/5U8U • Dalvik opcodes http://goo.gl/yUX3S • JUMPERZ.NET Blog: Android http://goo.gl/aVL3q • CodeGenerator.java http://goo.gl/78W6s