Initial commit

Author: eyJhb

android/reverse-engineering.md

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+# Android reverse engineering 
+
+This step will contain the following ...
+
+- Getting the .apk file (if not already)
+- Decompiling it to (.jar, .smali, .java files)
+- Inserting logging statements
+- Recompiling, aligning and signing
+
+# Getting the .apk
+
+## Gplaycli (preferred)
+- Project link - https://github.com/matlink/gplaycli
+
+Using gplaycli is the easiest way, just install it using `pip install gplaycli`, followed by `gplaycli -d com.eboks.activities`
+
+This outputs the .apk file in the current directory.
+
+## Online tools
+This only tool can be used, to get the apk file - https://apps.evozi.com/apk-downloader/
+
+Keep in mind, this might NOT be the newest version, but might be cached.
+
+# Decompiling
+
+## Decompiling to smali
+- Project link - https://bitbucket.org/iBotPeaches/apktool/downloads/
+
+Download the latest release of `apktool.jar`, and save it to the same directory as your `.apk`, I have the following structure.
+
+```
+- eboks/
+ - apktool.jar
+ - com.eboks.activities.apk
+```
+
+Use the following command, to get the smali code `java -jar apktool.jar d com.eboks.activities.jar`, and all the files are now in `com.eboks.activities`.
+
+## Decompiling to jar
+- Project link - https://github.com/pxb1988/dex2jar
+
+Go to the releases, and download the latest release (not nightly builds and not just the source).
+Extract it to a directory of your choice, I prefer the same as my .apk file, so I have the following structure
+
+```
+- eboks/
+ - dex2jar/
+ - com.eboks.activities.apk
+```
+
+Then just use the following command `./dex2jar/d2j-dex2jar.sh com.eboks.activities.apk`, which will result in a `.jar` with `-dex2jar.jar` appended to it.
+
+## Decompiling to java
+- Project link - https://bitbucket.org/mstrobel/procyon/downloads/
+
+Download the latest release so you have the following structure (this requires the previous `.jar` file).
+
+```
+- eboks/
+ - dex2jar/
+ - procyon.jar
+ - com.eboks.activities.apk
+ - com.eboks.activities-dex2jar.jar
+```
+
+To get the `.java` files, do the following `java -jar procyon.jar -jar com.eboks.activities-dex2jar.jar -o java-classes`.
+
+
+# Inserting logging statements
+- Project link - https://github.com/eyJhb/IGLogger
+
+This requires a bit more, since we need to use something called `iglogger`, download the `.smali` file, and place it in your apps smali root.
+
+This would be `com.eboks.activities/smali/iglogger.smali`, to use it, you need to place various debug statements in the code.
+
+Normally there will be a `.locals` in a function, so if you want to write a new string (to know what the next value will be), increase this, and use `.locals n-1`, to for your `vN`.
+
+Example
+
+```
+.method private static iv()[B
+    .locals 2
+
+    .line 68
+    new-instance v0, Ljava/security/SecureRandom;
+
+    invoke-direct {v0}, Ljava/security/SecureRandom;-><init>()V
+
+    const/16 v1, 0x10
+
+    .line 69
+    new-array v1, v1, [B
+
+    .line 70
+    invoke-virtual {v0, v1}, Ljava/security/SecureRandom;->nextBytes([B)V
+
+    return-object v1
+.end method
+```
+
+```
+.method private static iv()[B
+    .locals 3
+    const-string v2, "!!!loginEncryptHelper.iv!!!"
+    invoke-static {v2}, Liglogger;->d(Ljava/lang/String;)I 
+
+    .line 68
+    new-instance v0, Ljava/security/SecureRandom;
+
+    invoke-direct {v0}, Ljava/security/SecureRandom;-><init>()V
+
+    const/16 v1, 0x10
+
+    .line 69
+    new-array v1, v1, [B
+
+    .line 70
+    invoke-virtual {v0, v1}, Ljava/security/SecureRandom;->nextBytes([B)V
+    invoke-static {v1}, Liglogger;->d([B)I
+
+    return-object v1
+.end method
+```
+
+This will print out the information needed.
+
+# Recompiling, aligning and signing
+
+## Recompiling
+We here use `apktool` yet again - `java -jar apktool.jar b com.eboks.activities` (the folder name).
+This gives us a files in `com.eboks.activities/dists/com.eboks.activities.apk`, this file needs to be zipaligned.
+
+Install zipalign tool `apt install zipalign`, and use `zipalign -v -p 4 com.eboks.activities/dist/com.eboks.activities.apk app-alligned.apk`.
+
+Now for the signing, this is a little more tricky... We need `apksigner` which is a part of the `Android SDK Tools`, which will not be covered here.
+We also need to generate our signing keys using `keytools` (part of the Java JRE), where we can use this command `keytool -genkey -v -keystore my-release-key.jks -keyalg RSA -keysize 2048 -validity 10000 -alias my-alias`, I just use `123456` for all passwords prompts etc..
+
+Now when all this is done, you should be able to sign your alligned apk using ...
+
+```
+echo -n 123456 | apksigner sign --ks my-release-key.jks --out app-release.apk app-alligned.apk 
+```
+
+Now just install it!
+
+# Automated build script
+
+```
+rm builds/app-alligned.apk ; \
+java -jar apktool.jar b -o builds/app.apk app && \
+zipalign -v -p 4 builds/app.apk builds/app-alligned.apk && \
+echo -n 123456 | apksigner sign --ks my-release-key.jks --out builds/app-release.apk builds/app-alligned.apk 
+```

readme.md

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+# Guides
+This repository has various guides, for various tools, that I need to remember.
+
+Feel free to contribute with whatever...