  Internet of Things (IoT) data are increasingly viewed as a new form of
massively distributed and large scale digital assets, which are continuously
generated by millions of connected devices. The real value of such assets can
only be realized by allowing IoT data trading to occur on a marketplace that
rewards every single producer and consumer, at a very granular level.
Crucially, we believe that such a marketplace should not be owned by anybody,
and should instead fairly and transparently self-enforce a well defined set of
governance rules. In this paper we address some of the technical challenges
involved in realizing such a marketplace. We leverage emerging blockchain
technologies to build a decentralized, trusted, transparent and open
architecture for IoT traffic metering and contract compliance, on top of the
largely adopted IoT brokered data infrastructure. We discuss an Ethereum-based
prototype implementation and experimentally evaluate the overhead cost
associated with Smart Contract transactions, concluding that a viable business
model can indeed be associated with our technical approach.
