# Firmware Updates over the Air via LoRa: Unicast and Broadcast Combination for Boosting Update Speed
## 2 Related Work
### Security Update Requirements for IoT devices  
In recent years, cyber attacks have become a major problem for industries and IT services. They have the potential to inflict significant harm on businesses, products, and data. In [18], a summary of the major attacks that have occurred in the last 20 years against critical infrastructures was presented, also including an analysis of the types of attacks, consequences, vulnerabilities, victims, and attackers. The paper also provided an estimation of the number of major cyber attacks that will occur on critical infrastructure in the future.  
These attacks are continually evolving, growing increasingly sophisticated. Now, with the advent of the IoT, a new paradigm is emerging. IoT devices, ranging from smart home gadgets to industrial equipment, are small and physically isolated, but connected to a larger network, creating a tempting doorway for malicious actors. Many of these devices are responsible for handling sensitive personal data and performing critical tasks, making a loss of information or control a real concern [19]. As they are part of a larger system, individual deep checks of the devices are not performed very frequently, and this fact can be used by attackers to hide hacked devices from which they can read information, monitor workflows, influence system behavior, or communicate with external agents. With this in mind, it is important to establish cybersecurity strategies that keep devices updated in advance of any threat.  
Firmware serves as the foundational software embedded within IoT devices. Ensuring its security is essential to prevent unauthorized access, data breaches, and the potential manipulation of devices for malicious purposes. A recent review [20] emphasized the importance of addressing vulnerabilities in firmware to enhance the security posture of IoT ecosystems, thereby reinforcing trust and reliability for stakeholders.  
The authors of [21] conducted a comprehensive analysis of the components within an IoT operating system that receive the most updates post-deployment. They offered an exhaustive quantification of the energy consumption tied to each stage of the process. In [22], the authors present the barriers and cybersecurity targets of IoT devices and define an architectural concept for securing Over The Air updates. In both articles, the main reasons for software updates were similar: protocol and standard version updates; efficiency improvement; critical bug fixes and security updates; additional functionalities; integration with third-party IoT systems; or adopting new communication standards and protocols.  
Sometimes, devices are allocated in remote and inaccessible locations, especially in industrial IoT (IIoT) applications, highlighting the importance of protecting communications, particularly in critical processes such as FUOTA (Firmware Update Over The Air). As stated by [PERSON] and [PERSON] [23], ensuring the confidentiality, authenticity, and integrity of the data in these communications is essential. Although data encryption safeguards the firmware transmitted during FUOTA, it does not provide assurance against potential data corruption or unauthorized alterations. This is where data integrity and authenticity verification mechanisms become necessary. A checksum may act as a data integrity guardian, and digital signatures provide a layer of authenticity verification.  
As stated before, the present work is focused on the stage in which the firmware is sent through the wireless link. This is a critical moment as far as security is concerned, since the attack surface of a wireless protocol is, in general, higher than that of a wired one: devices can be reached through an expanded area that is potentially accessible by a greater number of systems, and more protocols are exposed due to the need for auto negotiation between the involved devices.