Android Native Library - How to match java references to sub_XXX function (static way)

Question

I'm currently learning how native functions are implemented among the ELF SO files contained inside an APK. I'm using IDA.

Native calls are always achieved in this way.

// First load the library 
class myClass{
public myClass(){
  super();
  v0 = system.loadLibrary("library-native"); 
  //then declare the methods 
}
public static native int nativeMethod(byte[] arg0, boolean arg1) ;
}
void a(){
  // then uses it 
  ret = this.nativeMethod(byte,bool) ; 
}

According to my little experiences in JNI, when looking to library-native.so using a disassembler I should see something like Java_package_name_libname_class_NativeMethod among the exported function.

I cannot see any of these elements. When I'm searching the desired function (nativeMethod in the past example) inside the disassembled code, I do not find any clue.

I wonder how Dalvik process manages to call the right function when a native call is performed, and how can I find myself the source code of the desired functions ?

Thanks

EDIT : I add the nm and readelf output to clarify.

nm --defined-only library-native.so 
nm library-native.so : no symbols
readelf -s library-native.so | grep nativeMethod // gives no output
//The only JNI related function 
nm -D --defined-only library-native.so | grep JNI
00XX: JNI_onLoad

Answer 1

Well, if the original file does not export the symbols, I can only think of two possibilities:

1. the methods are registered dynamically at load time.
2. (most likely) the file is obfuscated/encrypted and is decrypted on load.

In both cases the action probably happens in the JNI_onLoad function. You will need to debug it to see what's going on.