A public key infrastructure (PKI) has been widely deployed and well tested on the Internet. However, this standard practice of delivering scalable security has not yet been extended to the rapidly growing Internet of Things (IoT). Thanks to vendor hardware support and standardization of resource-efficient communication protocols, asymmetric cryptography is no longer unfeasible on small devices. To migrate IoT from poorly scalable, pair-wise symmetric encryption to PKI, a major obstacle remains: how do we certify the public keys of billions of small devices without manual checks or complex logistics? The process of certifying a public key in form of a digital certificate is called enrollment. In this paper, we design an enrollment protocol, called Indraj, to automate enrollment of certificate-based digital identities on resource-constrained IoT devices. Reusing the semantics of the Enrollment over Secure Transport (EST) protocol designed for Internet hosts, Indraj optimizes resource usage by leveraging an IoT stack consisting of Constrained Application Protocol (CoAP), Datagram Transport Layer Security (DTLS) and IPv6 over Low-Power Wireless Personal Area Networks (6LoWPAN).We evaluate our implementation on a low power 32-bit MCU, showing the feasibility of our protocol in terms of latency, power consumption and memory usage. Asymmetric cryptography enabled by automatic certificate enrollment will finally turn IoT devices into well behaved, first-class citizens on the Internet.

The Internet of Things, or the IoT, is an emerging, disruptive technology that enables physical devices to communicate across disparate networks. IP has been the de facto standard for seamless interconnectivity in the traditional Internet; and piggybacking on the success of IP, 6LoWPAN has been the first standardized technology to realize it for networks of resource-constrained devices. In the recent past Bluetooth Low Energy (BLE) a.k.a Bluetooth Smart - a subset of the Bluetooth v4.0 and the latest v4.2 stack, has surfaced as an appealing alternative, with many competing advantages over available low-power communication technologies in the IoT space such as IEEE 802.15.4. However, BLE is a closed standard and lacks open hardware and firmware support, something that hinders innovation and development in this field. In this article, we aim to overcome some of the constraints in BLE's core building blocks by making three contributions: first, we present the design of a new open hardware platform for BLE; second, we provide a Contiki O.S. port for the new platform; and third, we identify research challenges and opportunities in 6LoWPAN-connected Bluetooth Smart. We believe that the knowledge and insights will facilitate IoT innovations based on this promising technology

Glossy networks make use of concurrent transmissions to achieve rapid network flooding in wireless networks with high reliability. They are robust against jamming and header injection attacks. We find that Glossy floods can be hijacked by a packet injection attacker to penetrate into the network and cause severe loss. We demonstrate the design of such an attacker by evaluating its effectiveness in a 30-node testbed.

The past couple of years have seen a heightened interest in the Internet of Things (IoT), transcending industry, academia and government. As with new ideas that hold immense potential, the optimism of IoT has also exaggerated the underlying technologies well before they can mature into a sustainable ecosystem. While 6LoWPAN has emerged as a disruptive technology that brings IP capability to networks of resource constrained devices, a suitable radio technology for this device class is still debatable. In the recent past, Bluetooth Low Energy (LE) - a subset of the Bluetooth v4.0 stack - has surfaced as an appealing alternative that provides a low-power and loosely coupled mechanism for sensor data collection with ubiquitous units (e.g., smartphones and tablets). When Bluetooth 4.0 was first released, it was not targeted for IP-connected devices but for communication between two neighboring peers. However, the latest release of Bluetooth 4.2 offers features that makes Bluetooth LE a competitive candidate among the available low-power communication technologies in the IoT space. In this paper, we discuss the novel features of Bluetooth LE and its applicability in 6LoWPAN networks. We also highlight important research questions and pointers for potential improvement for its greater impact.

In this paper we present a new kind of Denial-of-Service attack against the PHY layer of low power wireless sensor networks. Overcoming the very limited range of jamming-based attacks, this attack can penetrate deep into a target network with high power efficiency. We term this the Droplet attack, as it attains enormous disruption by dropping small, payload-less frame headers to its victim's radio receiver, depriving the latter of bandwidth and sleep time. We demonstrate the Droplet attack's high damage rate to full duty-cycle receivers, and further show that a high frequency version of Droplet can even force nodes running on very low duty-cycle MAC protocols to drop most of their packets.

In this position paper, we advocate the use of bus snooping to trace radio events. Highly precise and unintrusive, the technique leads to potentially more efficient code and enables more insightful protocol analysis than conventional code instrumentation techniques.

Link quality estimation of reliability-crucial wireless sensor networks (WSNs) is often limited by the observability and testability of single-chip radio transceivers. The estimation is often based on collection of packer-level statistics, including packet reception rate, or vendor-specific registers, such as CC2420's Received Signal Strength Indicator (RSSI) and Link Quality Indicator (LQI). The speed or accuracy of such metrics limits the performance of reliability mechanisms built in wireless sensor networks. To improve link quality estimation in WSNs, we designed a powerful wireless communication monitor based on Software Defined Radio (SDR). We studied the relations between three implemented link quality metrics and packet reception rate under different channel conditions. Based on a comparison of the metrics' relative advantages, we proposed using a combination of them for fast and accurate estimation of a sensor network link.

Abstract—Intermediate-quality links often cause vulnerable connectivity in wireless sensor networks, but packet losses caused by such volatile links are not easy to trace. In order to equip link layer protocol designers with a reliable test and debugging tool, we develop a reactive interferer to generate packet loss patterns precisely. By using intentional interference to emulate parameterized lossy links with very low intrusiveness, our tool facilitates both robustness evaluation of protocols and flaw detection in protocol implementation.

Link quality estimation has been an important research topic in the wireless sensor networking community and researchers have developed a large number of different methods to estimate link quality. The commonly used CC2420 radio provides simple signal quality indicators. These are agile in that they react fast to changing link quality but they are inaccurate under complicated channel conditions. More sophisticated link quality estimators combine these simple metrics with packet reception statistics collected by the network stack. These approaches compensate the hardware-based metrics to a limited degree but they compromise agility and incur extra overhead. In this paper, we take a novel approach and develop a number of link quality metrics using a software defined radio. We evaluate our metrics under several channel conditions. The results show that they have good accuracy and can handle complicated channel conditions if combined properly.