The cluster between Internet of Things (IoT) and Social Networks (SN) enables the connection of people to the ubiquitous computing universe. In this framework, the information coming from the environment is provided by the IoT, and the SN brings the glue to allow human-to-device interactions. This article explores the novel paradigm for ubiquitous computing beyond IoT, denoted by Social Internet of Things (SIoT). Although there have been early-stage studies in social-driven IoT, they merely use one or some properties of SIoT to improve a number of specific performance variables. Therefore, this article first addresses a complete view on SIoT and key perspectives to envision the real ubiquitous computing. Thereafter, a literature review is presented along with the evolutionary history of IoT research from Intranet of Things to SIoT. Finally, this article proposes a generic SIoT architecture, and presents a discussion about enabling technologies, research challenges, and open issues.

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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.Index Terms-Access Control (AC), Internet of Things (IoT),