如何用R8混淆Kotlin属性

Question

我在Kotlin上有一个库，我想几乎完全模糊，但不影响公共类、属性和方法。下面是一个我打算混淆的公共类的例子：

class SomeClass(val propertyToShow: SomePublicClass, private val propertyToHide: SomeOtherPublicClass) {
fun methodToShow(someArg: SomeArg) {
// Some code
}
private fun methodToHide(someOtherArg: SomeOtherArg) {
// Some more code
}
}

ProGuard文件是基于一个典型的ProGuard库文件，如下所示：

-keepattributes SourceFile,LineNumberTable
-renamesourcefileattribute SourceFile
-dontwarn javax.annotation.**
-keepnames class okhttp3.internal.publicsuffix.PublicSuffixDatabase
-dontwarn org.codehaus.mojo.animal_sniffer.*
-dontwarn okhttp3.internal.platform.ConscryptPlatform
-keepattributes Signature
-keepattributes *Annotation*
-dontwarn sun.misc.**
-keep class com.google.gson.stream.** { *; }
-keep class * implements com.google.gson.TypeAdapterFactory
-keep class * implements com.google.gson.JsonSerializer
-keep class * implements com.google.gson.JsonDeserializer
-keepclassmembers,allowobfuscation class * {
@com.google.gson.annotations.SerializedName <fields>;
}
-keep public class * {
public protected *;
}
-keepclassmembernames class * {
java.lang.Class class$(java.lang.String);
java.lang.Class class$(java.lang.String, boolean);
}
-keepclasseswithmembernames class * {
native <methods>;
}
-keeppackagenames **
-keepattributes Exceptions,InnerClasses,Signature,Deprecated,SourceFile,LineNumberTable,*Annotation*,EnclosingMethod,Synthetic,PermittedSubclasses
-keepparameternames
-renamesourcefileattribute SourceFile
-keepclassmembers class **$WhenMappings {
<fields>;
}
-keep class kotlin.Metadata { *; }
-keep class kotlin.** { *; }
-keep class kotlin.Metadata { *; }
-keep class kotlin.reflect.** { *; }
-dontwarn kotlin.reflect.**
-dontwarn kotlin.**
-keepclassmembers class **$WhenMappings {
<fields>;
}
-keepclassmembers class kotlin.Metadata {
public <methods>;
}
-assumenosideeffects class kotlin.jvm.internal.Intrinsics {
static void checkParameterIsNotNull(java.lang.Object, java.lang.String);
}
-keepclassmembers,allowobfuscation class * {
@javax.inject.* *;
@dagger.* *;
<init>();
}
-keep class javax.inject.** { *; }
-keep class **$$ModuleAdapter
-keep class **$$InjectAdapter
-keep class **$$StaticInjection
-keep class dagger.** { *; }
-keepclassmembers class * extends java.lang.Enum {
public static **[] values();
public static ** valueOf(java.lang.String);
}
-keepclassmembers class * implements java.io.Serializable {
static final long serialVersionUID;
static final java.io.ObjectStreamField[] serialPersistentFields;
private void writeObject(java.io.ObjectOutputStream);
private void readObject(java.io.ObjectInputStream);
java.lang.Object writeReplace();
java.lang.Object readResolve();
}

运行./gradlew assembleRelease会生成.aar文件。它的SomeClass.class看起来是这样的(如果我们通过Android Studio查看它(

public final class SomeClass public constructor(propertyToShow: SomePublicClass, propertyToHide: SomeOtherPublicClass) {

public final val propertyToShow: SomePublicClass /* compiled code */
private final val propertyToHide: SomeOtherPublicClass /* compiled code */
public final fun methodToShow(someArg: SomeArg): kotlin.Unit { /* compiled code */ }
private final fun a(someOtherArg: SomeOtherArg): kotlin.Unit { /* compiled code */ }

}

正如我们所看到的，私有方法的名称被混淆了，但它的参数不如私有属性。无论我们用ProGuard还是R8混淆它，结果都是一样的。

有可能混淆Kotlin源代码的私有属性和私有方法的参数吗？或者它是没有意义的，因为它不会干扰其他人进行逆向工程？

Answer 1

所以本文或多或少地解释了这个问题的答案。基本上，问题是代码确实被正确地混淆了，但仍然有Kotlin元数据，安卓工作室正在基于该元数据重建代码。