# A Complete Key Management Scheme for LoRaWAN v1.1 +
## 2 Related Work  
To address the above security vulnerabilities, different authors have proposed different key management solutions for LoRaWAN in recent works. Strengths and weaknesses of the most recent works have been examined. [PERSON] and [PERSON] [8] reviewed LoRaWAN v1.1 security framework and enhanced a root key update scheme that makes the LoRaWAN root keys more secure, because static root keys throughout the lifetimes of the device can make attacker has enough time to obtain knowledge of the session key derivation. The experimental results show that this scheme generates a high degree of randomness with higher computing efficiency compared to hash-based Key Derivation Function (KDF). However, the paper [8] did not have other solutions to address the session key update issue, key back-up, recovery, revocation, and backward compatibility issues. Hence, that makes our paper a more complete key management scheme. Furthermore, the randomness test in [8] was using 1000 key samples from the outputs of the Rabbit-based KDF which are used to calculate the standard deviation and Probability Density Function (PDF). The output has shown evenly spread block values. On the other hand, our randomness tests were strictly based on the NIST Randomness Guidelines [26]. Hence, a strict randomness performance can be ensured. [PERSON] et al. [9] evaluated LoRaWAN's security vulnerabilities and presented a key exchange protocol based on the enhanced Elliptic Curve Diffie Hellman (ECDH), the results have shown that better performance (network latency and signal overhead reduction) for the proposed protocol in comparison with other security protocols, namely Datagram Transport Layer Security-Pre-Shared Key (DTLS-PSK) and Datagram Transport Layer Security-Elliptic Curve Cryptography (DTLS-ECC). Although the paper [9] focused on the v1.02 of the LoRaWAN framework, the paper [9] has indicated compatibles with version 1.1 of LoRaWAN. The reason is that they have proposed a protocol to allow the end device and the application server to exchange the session key securely by using the ECDH-based key exchange and the Elliptic Curve Digital Signature Algorithm (ECDSA) digital signature to overcome the problem that the network server has known the AppSKey, which aims to protect the application data. [PERSON] et al. [7] reviewed LoRaWAN's security vulnerabilities and suggested a different approach based on the Ephemeral Diffie-Hellman Over COSE (EDHOC), where COSE stands for Concise binary object representation Object Signing and Encryption, due to its flexibility in the update of session keys, its low computational cost, and the limited message exchanges needed. Their contribution is to reduce the handshake overhead by about 31% than using the Datagram Transport Layer Security (DTLS) Protocol. Similar to [PERSON] et al. [9], both solutions focused on key exchange protocol. Therefore, some works could be done on other areas to further improve the LoRaWAN key management scheme. For example, the session key generation, by using a more efficient session key generator can further reduce the cost of the key update, since more keys can be produced to allow more frequent key updates. [PERSON] et al. [10] presented a secure key management scheme for static key update remotely using a Hierarchical Deterministic (HD) wallet and key exchange through an Elliptic Curve Diffie-Hellman (ECDH) algorithm. The result shows that the key exchange algorithm performed better than Diffie-Hellman (DH) algorithm. Similar to [8], both focused on key updating of the static root keys. Also, similar to [7; 9], the key exchange algorithms have been improved. [PERSON] and [PERSON] [11] in the paper stated a key management scheme by using a delegation named Assisted Mode to overcome the security concern of the static root keys due to the lifetime of the static root keys can expose the weakness to attackers. Unlike [8; 10] require algorithms to remotely update root keys.