Attribute-Based Encryption and Sticky Policies for Data Access Control in a Smart Home Scenario: a Comparison on Networked Smart Object Middleware

Regulating the access to the Internet of Things (IoT) network's resources is a complex-prone task, which requires to pay a great attention on how policies are defined, shared, and enforced. The present paper considers the specific context of a smart home, which represents one of the main IoT application domains, and it focuses on two solutions proposed in the literature to cope with the aforementioned issues. On the one side, approaches based on Attribute-Based Encryption (ABE) allow one to encrypt data for multiple recipients, in such a way that only those recipients whose attributes satisfy a given access policy can decrypt afterwards. ABE guarantees a high level of customization due to the variety of attributes which can be defined, and it is also flexible enough to be adapted to different kinds of scenarios. On the other side, approaches based on sticky policies allow to attach an access policy directly to the data itself, and to employ a trusted authority to evaluate and enforce the policy itself. Sticky policies also guarantee a highly distributed and customizable enforcement of access control rules. In this paper, we compare the advantages and the drawbacks in terms of performance and robustness of such two techniques by means of their integration within the prototype of an IoT middleware, named NetwOrked Smart object (NOS). Hence, the effectiveness of the presented solutions is validated by means of a real test-bed in the smart home scenario, in terms of storage occupancy, CPU load, and data retrieval delay. The final goal is to reveal the best approach to be used depending on the application's requirements.