Access control in the Internet of Things: a survey of existing approaches and open research questions

The Internet of Things operates in a personal-data-rich sector, which makes security and privacy an increasing concern for consumers. Access control is thus a vital issue to ensure trust in the IoT. Several access control models are today available, each of them coming with various features, making them more or less suitable for the IoT. This article provides a comprehensive survey of these different models, focused both on access control models (e.g., DAC, MAC, RBAC, ABAC) and on access control architectures and protocols (e.g., SAML and XACML, OAuth 2.0, ACE, UMA, LMW2M, AllJoyn). The suitability of each model or framework for IoT is discussed. In conclusion, we provide future directions for research on access control for the IoT: scalability, heterogeneity, openness and flexibility, identity of objects, personal data handling, dynamic access control policies, and usable security.