## 2 Radio Communication Technologies
### The Main Characteristics of LPWAN Technologies
#### 2.2.6 Security and Privacy Support  
As more devices are being connected, the tracking of information is becoming more complex. Some surveys show that up to 90% of connected devices collect sensitive information, and yet 70% of such data do not have any encryption. Many IoT devices also generate data related to personal behavior, providing new business opportunities that help companies in reaching their marketing goals [24]. Unlike LoRa and Sigfox, NB-IoT operates within a licensed spectrum and is a cellular radio technology (like 2G, 3G, and 4G). All of these LPWAN networks can be used in serious applications such as asset tracking and remote monitoring. Such scenarios require reliability and guaranties of data and communication security. An attack during data transmission can cause financial losses and even put people's lives in danger [25]. The data collected and transmitted within IoT networks are categorized as big data and are considered unstructured data. Many research studies are being done on big data security but they are in the initial stage. It is more difficult to secure unstructured data and no specific security provision method has been created for big data to date, so the security support in LPWAN technologies needs to be taken into account [26]. As in other radio connections, the three dominant LPWAN technologies, LoRaWAN, Sigfox, and NB-IoT, are exposed to possible security attacks and issues. There are some major subgroups of potential attacks on LPWAN depending on the technology purpose:  
* **Data-focused attacks**, which focus on accessing the data that circulate in LPWAN networks;
* **DoS or denial of service attacks**, with the intent to block or even inhibit the complete data transfer;
* **Monetary-focused attacks**, where an attacker may look into the financial losses for the operators of the LPWAN or the owners. For instance, some attackers try to send data at no cost (by putting the costs on other users);
* **Hardware exploitation**, where the aim is to gain control over the elements of the network for other operations (such as mining cryptocurrencies, spying, misusing the elements to launch a DoS attack);
* **Hybrid attacks**, which are performed to achieve several aims at a time [24]. Generally, the main LPWAN technologies define certain levels of security support. The security definition in Sigfox is based on symmetric cryptography, although some security characteristics, such as encryption, are not defined by default and are performed on-demand. Sigfox defines mechanisms for credential provisioning; identity protection; the authentication of devices, networks, messages, subscribers, data integrity, and confidentiality; and even protection against replays in case of a packet replay attack. It also supports reliable delivery. The non-IP data delivery (NIDD) in Sigfox is deployed over the air and the Internet Protocol (IP) packets are delivered via a virtual private network (VPN)-Secure Sockets Layer (SSL), providing acceptable security in this part. However, there is no mechanism defined for packet prioritization, forward secrecy, and algorithm negotiation. Sigfox does not specify update procedures so they need to be handled in the application layer [24]. LoRaWAN's security, as with Sigfox, is defined by symmetric cryptography and supports credential provisioning. However, the identity protection is partial so more up-to-date identity protection methods, such as the Temporary Mobile Subscriber Identity (TMSI), are currently missing. Additionally, no subscriber authentication and no device or network authentication are supported in LoRaWAN. The quality of service and mechanisms for prioritization are not defined in LoRaWAN. Like Sigfox, LoRaWAN uses NIDD over the radio layer and the communication occurs via VPN/SSL protocols. LoRaWAN protects the data integrity and data confidentiality and provides replay protection, reliable delivery, network monitoring, and filtering services. The security of NB-IoT is similar to definition in its root network system LTE.