## 1 Introduction  
Smart Cities are integrating functionality like real-time vehicle management, anti-theft systems, and traffic management [1], which can reduce traffic congestion and improve the driving experience. For example, it is workable to optimize traffic flow, reduce congestion, and improve private and public transportation services by evaluating real-time data from sensors and cameras installed in strategic locations. Furthermore, smart cities can catalyze citizen empowerment and improve the engagement of public administrations with their citizens by delivering individualized services. In recent years, the automotive industry has begun to examine sensors for enabling smart features within vehicles. Such integration paves the door for a more connected and safe driving experience. These functionalities leverage a myriad of sensors that are distributed in the city and in the cars enabling real-time collaboration thanks to emerging technologies like 5G, NB-IoT, WiFi, or long range (LoRa). This new era of smart communication evolved from classical internet of things (IoT), composed of a few devices, to a more complex system named internet of vehicles (IoV). Starting from 2019, many manufacturers have released cars equipped with smart systems. Considering the heterogeneous components currently existing, it is possible to distinguish five major approaches [2] to vehicle communication and connectivity: vehicle-to-vehicle (V2V), where vehicles communicate among each other; vehicle-to-infrastructure (V2I), characterized by vehicles that send and receive data from external gateways; vehicle-to-cloud (V2C), where vehicles directly send data to cloud services; vehicle-to-pedestrian (V2P), where vehicles communicate with the surrounding environment, such as pedestrians; and vehicle-to-everything (V2X), which can be a combination of the previously defined systems. Among these systems, the most relevant ones are those related to the ACN systems, which, by leveraging many sensors and reliable communication, are able to save human lives. Road systems are becoming more congested due to the increasing number of cars that transit through them, potentially leading to crashes. The number of injuries from car crashes has increased over the last few years, as reported by [PERSON] et al. [3], where traffic intersections are the most critical point. ACN systems have the ability to provide earlier notification of a vehicle crash enabling a faster and precise emergency response service (ERS) response by sending a notification with the crash location identification. Such systems are able to increase the probability of survival; as shown by [PERSON] et al. [4], advanced driver assistance system (ADAS) (a complementary system for ACN) are able to reduce crashes by 14%. Many standards have been proposed by the International Organization for Standardization (ISO) and Society of Automotive Engineers (SAE) to assess the quality and security of cars produced. Among them, ISO/SAE 21434 [5] attempts to redefine and give the original equipment manufacturer (OEM) and suppliers a complete standard for security and quality checks regarding cybersecurity. [PERSON] et al. [6] compared this new standard with the existing ones, highlighting the correlation with the others; showing the completeness of ISO/SAE 21434, which includes all the other protocols in a compact form. In particular, sections like information sharing and impact analysis are in common with ISO 26262-2 [7] making this new standard more complete. The authors investigate the security and privacy of ACN systems in light of the growing complexity of embedded systems within cars. As previously said, these systems are the most important and need appropriate security. All the elements of a typical ACN will be taken into account as part of an analysis conducted following the ISO/SAE 21434 standardization. To better comprehend the components and their interactions, two architectures will be specifically contrasted. The analysis will adhere to the protocol exactly.