Access Control in Adversarial Environments for IoT-oriented Distributed Ledgers

The surge of Internet of Things (IoT) applications requires distributed systems capable of securely exchanging messages and immutably recording data. While traditional blockchain architectures were not designed with IoT in mind, more recent Distributed Ledger Technologies (DLTs), which are not based on proof of work, can be considered as a solution to deal with the above requirements. However, without proof of work, these ledgers require an explicit way to manage the rate at which messages are issued and disseminated. In this work, we present an access control scheme for IoT-oriented DLTs, that is the mechanism used to choose which messages can be written to the ledger. Our approach aims to efficiently exploit the available network resources (bandwidth, processing power) and to guarantee fair access depending on node reputation. While these concepts have already been touched by well-known areas of networking research, such as TCP and quality of service, in DLT networks this problem is harder since nodes cannot trust familiar feedback measurements, such as packet acknowledgements or congestion notifications. In this paper, we design a completely decentralised mechanism which involves a round robin-based scheduler and a TCP-inspired rate setter. Extensive simulations show that our approach provides fair access, guarantees that all honest nodes eventually receive the same messages, and makes sure that malicious nodes cannot degrade performance or affect security.