## 1 Introduction
These methods and the LoRaWAN share a common principle that exchanging messages in the public domain requires a cryptographic hash function with optimal collision resistance properties. In other words, the auxiliary materials for the key establishment are hashed and then sent to other parties through the handshake. The confidentiality of the materials is guaranteed by the hash function. Researchers have also tried to achieve a lightweight feature for secure communication of IoT devices with stronger cryptography. Highly secure cryptography, such as public key cryptography (PKC), has been known to be expensive due to the limited computing resources of sensor nodes. The traditional Diffie-Hellman key exchange used in modern computers requires an authentication feature to prevent man-in-the-middle attacks. [PERSON] et al. [8] indicated that IoT devices cannot afford the significant computational cost. Additionally, node devices need to update their public and private keys to prevent ciphertext-only attacks similar to the root key revelation of LoRaWAN. On the other hand, [PERSON] et al. [9] suggested that a careful selection of settings for public-key-based ciphersuites would ensure the security of the IoT network and reduce overheads in the handshake. [PERSON] et al. [10] claimed that public key cryptography has become feasible on the latest generation of constrained devices and supported this statement by proposing an elliptic curve cryptography (ECC)-based protocol for IoT devices. Moreover, other than LoRaWAN, recent works for highly sensitive data transmission (healthcare, e-payment) applied PKC with various IoT communication technologies, like ZigBee, RFID, and NFC. [PERSON] et al. [11] utilized the Zigbee wireless technology to establish a reliable network management (RNM-SC) for a smart healthcare system. A group of sensor nodes are managed by a local coordinator and connected to a ZigBee router. The system offers an optimization in the transmission path, which is handled by the router, and a node table comprising information on close-distance nodes. The underlying key establishment to ensure authenticity relies on the station-to-station algorithm, which is based on the classic Diffie-Hellman method. Furthermore, RNM-SC applies Blum-Goldwasser asymmetric cryptography to encrypt and decrypt sensitive data. An extensive review by [PERSON] [12] addressed the security challenges and threats of systems based on RFID and NFC technologies. It is suggested that the deployment of a strong cryptography scheme is a feasible solution to reinforce RFID's communication security. The review also summarized the most recent studies on cryptography schemes for RFID and NFC and showed a diversity of encryption methodologies for solutions implemented for different applications. Based on the statistical data, the author suggested that cryptography systems like ECC are preferable for semi-active and active tag devices. Meanwhile, a lightweight scheme is favorable for passive tag devices where resource limitations are more strict. In addition, many recent works shared the same methodology of integrating strong cryptography, like ECC, to secure communication in IoT networks [13; 14; 15]. Our proposal applies two schemes that can be constructed by using ECC. When constructing a protocol that uses ECC-based handshakes for node devices with small processors and low-bandwidth transceivers, there are several important factors to consider. First, a key establishment protocol that is proposed under a specific operating assumption must ensure security properties, such as confidentiality and authentication. Second, the number of computations executed at the node side is a critical issue that should be addressed. Third, the size and number of exchange messages should be reduced for low-bandwidth communication.