The Internet of Things (IoT) is a heterogeneous network of interconnected objects or
‘things’ that are typically connected via the Internet. Trust in most IoT networks is presumed
implicitly. This implicit trust assumption can be abused by adversaries to disrupt the network
and manipulate reputations of trusted devices. To tackle IoT trust issues, we use permissioned
blockchains that utilize Smart Contracts (executable policies) to evaluate and refine IoT
devices’ trust. Blockchains replicate a permanent append-only record of all transactions
occurring on a network on multiple devices. This prevents adversaries from modifying previous
transactions to influence trust evaluations. In this thesis, we propose an IoT trust model that
uses Blockchains to record and validate IoT devices’ identities and dynamically evaluates the
trustworthiness of devices in the IoT network. Moreover, our model allows for different levels
of security based on the sensitivity of data being transmitted across the IoT network.
Transactional properties of permissioned blockchains
