OAuth 2.0 meets Blockchain for Authorization in Constrained IoT Environments

We present models for utilizing blockchain and smart contract technology with the widely used OAuth 2.0 open authorization framework to provide delegated authorization for constrained IoT devices. The models involve different trade-offs in terms of privacy, delay, and cost, while exploiting key advantages of blockchains and smart contracts. These include linking payments to authorization grants, immutably recording authorization information and policies in smart contracts, and offering resilience through the execution of smart contract code on all blockchain nodes.