Blockchain-based authentication and authorization for smart city applications

The platforms supporting the smart city applications are rarely implemented from scratch by a municipality and/or totally owned by a single company, but are more typically realized by integrating some existing ICT infrastructures thanks to a supporting platform, such as the well known FIWARE platform. Such a multi-tenant deployment model is required to lower the initial investment costs to implement large scale solutions for smart cities, but also imposes some key security obstacles. In fact, smart cities support critical applications demanding to protect the data and functionalities from malicious and unauthorized uses. Equipping the supporting platforms with proper means for access control is demanding, but these means are typically implemented according to a centralized approach, where a single server stores and makes available a set of identity attributes and authorization policies. Having a single root of trust is not suitable in a distributed and cooperating scenario of large scale smart cities due to their multi-tenant deployment. In fact, each of the integrated system has its own set of security policies, and the other systems need to be aware of these policy, in order to allow a seamless use of the same credentials across the overall infrastructure (realizing what is known as the single-sign-on). This imposes the problem of consistent and secure data replicas within a distributed system, which can be properly approached by using the blockchain technology. Therefore, this work proposes a novel solution for distributed management of identity and authorization policies by leveraging on the blockchain technology to hold a global view of the security policies within the system, and integrating it in the FIWARE platform. A detailed assessment is provided to evaluate the goodness of the proposed approach and to compare it with the existing solutions