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/encoders/proto/ProtobufEncoder.java

@@ -0,0 +1,83 @@
+package com.google.firebase.encoders.proto;
+
+import com.google.firebase.encoders.EncodingException;
+import com.google.firebase.encoders.ObjectEncoder;
+import com.google.firebase.encoders.ObjectEncoderContext;
+import com.google.firebase.encoders.ValueEncoder;
+import com.google.firebase.encoders.config.Configurator;
+import com.google.firebase.encoders.config.EncoderConfig;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.util.HashMap;
+import java.util.Map;
+
+/* loaded from: classes3.dex */
+public class ProtobufEncoder {
+    private final ObjectEncoder<Object> fallbackEncoder;
+    private final Map<Class<?>, ObjectEncoder<?>> objectEncoders;
+    private final Map<Class<?>, ValueEncoder<?>> valueEncoders;
+
+    public ProtobufEncoder(Map<Class<?>, ObjectEncoder<?>> map, Map<Class<?>, ValueEncoder<?>> map2, ObjectEncoder<Object> objectEncoder) {
+        this.objectEncoders = map;
+        this.valueEncoders = map2;
+        this.fallbackEncoder = objectEncoder;
+    }
+
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    public void encode(Object obj, OutputStream outputStream) throws IOException {
+        new ProtobufDataEncoderContext(outputStream, this.objectEncoders, this.valueEncoders, this.fallbackEncoder).encode(obj);
+    }
+
+    /* loaded from: classes3.dex */
+    public static final class Builder implements EncoderConfig<Builder> {
+        private static final ObjectEncoder<Object> DEFAULT_FALLBACK_ENCODER = new a(1);
+        private final Map<Class<?>, ObjectEncoder<?>> objectEncoders = new HashMap();
+        private final Map<Class<?>, ValueEncoder<?>> valueEncoders = new HashMap();
+        private ObjectEncoder<Object> fallbackEncoder = DEFAULT_FALLBACK_ENCODER;
+
+        public static /* synthetic */ void lambda$static$0(Object obj, ObjectEncoderContext objectEncoderContext) throws IOException {
+            throw new EncodingException("Couldn't find encoder for type " + obj.getClass().getCanonicalName());
+        }
+
+        public ProtobufEncoder build() {
+            return new ProtobufEncoder(new HashMap(this.objectEncoders), new HashMap(this.valueEncoders), this.fallbackEncoder);
+        }
+
+        public Builder configureWith(Configurator configurator) {
+            configurator.configure(this);
+            return this;
+        }
+
+        public Builder registerFallbackEncoder(ObjectEncoder<Object> objectEncoder) {
+            this.fallbackEncoder = objectEncoder;
+            return this;
+        }
+
+        @Override // com.google.firebase.encoders.config.EncoderConfig
+        public <U> Builder registerEncoder(Class<U> cls, ObjectEncoder<? super U> objectEncoder) {
+            this.objectEncoders.put(cls, objectEncoder);
+            this.valueEncoders.remove(cls);
+            return this;
+        }
+
+        @Override // com.google.firebase.encoders.config.EncoderConfig
+        public <U> Builder registerEncoder(Class<U> cls, ValueEncoder<? super U> valueEncoder) {
+            this.valueEncoders.put(cls, valueEncoder);
+            this.objectEncoders.remove(cls);
+            return this;
+        }
+    }
+
+    public byte[] encode(Object obj) {
+        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
+        try {
+            encode(obj, byteArrayOutputStream);
+        } catch (IOException unused) {
+        }
+        return byteArrayOutputStream.toByteArray();
+    }
+}