University of Glasgow Philips Research Philips Research The IP-based Internet of Things (IoT) refers to the pervasive interaction of smart devices and people enabling new applications by means of IP protocols. Traditional IP protocols will be further complemented by 6LoWPAN and CoAP to make the IoT feasible on small devices. Security and privacy are a must for such an environment. Due to mobility, limited bandwidth, resource constraints, and new communication topologies, existing security solutions need to be adapted. We propose a security architecture for the IoT in order to provide network access control to smart devices, the management of keys and securing unicast/multicast communication. Devices are authenticated and granted network access by means of a pre-shared key (PSK) based security handshake protocol. The solution is based on Datagram Transport Layer Security (DTLS). Through the established secure channels, keying materials, operational and security parameters are distributed, enabling devices to derive session keys and group keys. The solution relies on the DTLS Record Layer for the protection of unicast and multicast data flows. We have prototyped and evaluated the security architecture. The DTLS architecture allows for easier interaction and interoperability with the Internet due to the extensive use of TLS. However, it exhibits performance issues constraining its deployment in some network topologies and hence would require further optimizations.