Table 4.

Summary of access management based solutions.

Solutions	Working Principle	DDoS Attack Mitigation			Weaknesses	Strengths
		Prevention	Detection	Reaction
PKAM [107,108,109]	Based on public key to manage access. Reject requests if the requester’s public key is not registered or unavailable.	Yes	No	No	Cannot prevent DDoS attacks if attackers use multiple public keys.	Prevent DDoS attacks by limiting unauthorised access.
PUFAM [7,110]	Use PUF to verify the authenticity of the IoT devices. All tampered, fake and cloned devices will be detected, which can prevent devices from becoming part of a botnet.	Yes	No	No	No experiments to prove the robustness against DDoS attacks.	It is a lightweight access management solution which is suitable for an IoT environment.