Attribute-based Encryption on Ethereum for Smart City Access Control

Smart city infrastructures are resulting in a concern regarding proper security and fine- grained access control for the access of the sensitive data generated by the interconnected devices and services. Having rich yet heterogeneous environments is a common scenario for organizations nowadays, and conventional access control mechanisms often do not suffice to provide support for flexible, scalable and decentralized authorization. Here, we develop a new access control method that leverages Cipher text-Policy Attribute-Based Encryption (CP-ABE) and Ethereum smart contracts to realize decentralized and fine-grained data access in smart city applications. Users are allowed to access and decrypt information only if they own a suitable set of attribute. They leverage smart contracts on the Ethereum blockchain to perform attribute verification, issue keys, and log access actions, which removes the need to trust a centralized authority. We also describe the architecture of the system, the design of smart contracts, and an implementation prototype. The experimental results can validate the computational efficiency, the gas consumption and the policy expressiveness of our approach, showing that it is a promising solution for secure and transparent data access control model in smart cities.