Primer paso de la investigacion. Se aportan el .apk, las carpetas con el apk extraido y el apk descompilado. El archivo API_DOCUMENTATION.md es un archivo donde se anotaran los descubrimientos del funcionamiento de la API, y los .py son scripts para probar la funcionalidad de la API con los métodos que vayamos encontrando. Finalmente, los archivos .js son scripts de Frida para extraer informacion de la APP durante la ejecucion.

apk_decompiled/sources/com/google/firebase/messaging/TopicsStore.java

@@ -0,0 +1,95 @@
+package com.google.firebase.messaging;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.util.Log;
+import java.lang.ref.WeakReference;
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+import java.util.NoSuchElementException;
+import java.util.concurrent.Executor;
+
+/* JADX INFO: Access modifiers changed from: package-private */
+/* loaded from: classes3.dex */
+public final class TopicsStore {
+    private static final String DIVIDER_QUEUE_OPERATIONS = ",";
+    static final String KEY_TOPIC_OPERATIONS_QUEUE = "topic_operation_queue";
+    static final String PREFERENCES = "com.google.android.gms.appid";
+    private static WeakReference<TopicsStore> topicsStoreWeakReference;
+    private final SharedPreferences sharedPreferences;
+    private final Executor syncExecutor;
+    private SharedPreferencesQueue topicOperationsQueue;
+
+    private TopicsStore(SharedPreferences sharedPreferences, Executor executor) {
+        this.syncExecutor = executor;
+        this.sharedPreferences = sharedPreferences;
+    }
+
+    public static synchronized void clearCaches() {
+        synchronized (TopicsStore.class) {
+            WeakReference<TopicsStore> weakReference = topicsStoreWeakReference;
+            if (weakReference != null) {
+                weakReference.clear();
+            }
+        }
+    }
+
+    public static synchronized TopicsStore getInstance(Context context, Executor executor) {
+        TopicsStore topicsStore;
+        synchronized (TopicsStore.class) {
+            try {
+                WeakReference<TopicsStore> weakReference = topicsStoreWeakReference;
+                topicsStore = weakReference != null ? weakReference.get() : null;
+                if (topicsStore == null) {
+                    topicsStore = new TopicsStore(context.getSharedPreferences(PREFERENCES, 0), executor);
+                    topicsStore.initStore();
+                    topicsStoreWeakReference = new WeakReference<>(topicsStore);
+                }
+            } catch (Throwable th) {
+                throw th;
+            }
+        }
+        return topicsStore;
+    }
+
+    private synchronized void initStore() {
+        this.topicOperationsQueue = SharedPreferencesQueue.createInstance(this.sharedPreferences, KEY_TOPIC_OPERATIONS_QUEUE, DIVIDER_QUEUE_OPERATIONS, this.syncExecutor);
+    }
+
+    public synchronized boolean addTopicOperation(TopicOperation topicOperation) {
+        return this.topicOperationsQueue.add(topicOperation.serialize());
+    }
+
+    public synchronized void clearTopicOperations() {
+        this.topicOperationsQueue.clear();
+    }
+
+    public synchronized TopicOperation getNextTopicOperation() {
+        return TopicOperation.from(this.topicOperationsQueue.peek());
+    }
+
+    public synchronized List<TopicOperation> getOperations() {
+        ArrayList arrayList;
+        List<String> list = this.topicOperationsQueue.toList();
+        arrayList = new ArrayList(list.size());
+        Iterator<String> it = list.iterator();
+        while (it.hasNext()) {
+            arrayList.add(TopicOperation.from(it.next()));
+        }
+        return arrayList;
+    }
+
+    public synchronized TopicOperation pollTopicOperation() {
+        try {
+        } catch (NoSuchElementException unused) {
+            Log.e(Constants.TAG, "Polling operation queue failed");
+            return null;
+        }
+        return TopicOperation.from(this.topicOperationsQueue.remove());
+    }
+
+    public synchronized boolean removeTopicOperation(TopicOperation topicOperation) {
+        return this.topicOperationsQueue.remove(topicOperation.serialize());
+    }
+}