  As the de facto routing protocol for many Internet of Things (IoT) networks
nowadays, and to assure the confidentiality and integrity of its control
messages, the Routing Protocol for Low Power and Lossy Networks (RPL)
incorporates three modes of security: the Unsecured Mode (UM), Preinstalled
Secure Mode (PSM), and the Authenticated Secure Mode (ASM). While the PSM and
ASM are intended to protect against external routing attacks and some replay
attacks (through an optional replay protection mechanism), recent research
showed that RPL in PSM is still vulnerable to many routing attacks, both
internal and external. In this paper, we propose a novel secure mode for RPL,
the Chained Secure Mode (CSM), based on the concept of intraflow Network Coding
(NC). The CSM is designed to enhance RPL resilience and mitigation capability
against replay attacks while allowing the integration with external security
measures such as Intrusion Detection Systems (IDSs). The security and
performance of the proposed CSM were evaluated and compared against RPL in UM
and PSM (with and without the optional replay protection) under several routing
attacks: the Neighbor attack (NA), Wormhole (WH), and CloneID attack (CA),
using average packet delivery rate (PDR), End-to-End (E2E) latency, and power
consumption as metrics. It showed that CSM has better performance and more
enhanced security than both the UM and PSM with the replay protection, while
mitigating both the NA and WH attacks and significantly reducing the effect of
the CA in the investigated scenarios.
