Michael Brünig

DTLS based security and two-way authentication for the Internet of Things

In this paper, we introduce the first fully implemented two-way authentication security scheme for the Internet of Things (IoT) based on existing Internet standards, specifically the Datagram Transport Layer Security (DTLS) protocol. By relying on an established standard, existing implementations, engineering techniques and security infrastructure can be reused, which enables easy security uptake. Our proposed security scheme is therefore based on RSA, the most widely used public key cryptography algorithm. It is designed to work over standard communication stacks that offer UDP/IPv6 networking for Low power Wireless Personal Area Networks (6LoWPANs). Our implementation of DTLS is presented in the context of a system architecture and the schemes feasibility (low overheads and high interoperability) is further demonstrated through extensive evaluation on a hardware platform suitable for the Internet of Things.

Fast full-search block matching

A fast full-search block-matching algorithm is developed. The matching criterion is the sum of absolute differences or the mean-square error. The algorithm evaluates lower bounds for the matching criteria for subdivided blocks in order to reduce the number of search positions. It also uses the lower bounds for a fast calculation of the matching criterion for the remaining search positions. The computational complexity of the algorithm is evaluated and compared to the three-step search strategy. The search result of the algorithm is identical to the search result of the exhaustive search.

A Bayesian method for probable surface reconstruction and decimation

We present a Bayesian technique for the reconstruction and subsequent decimation of 3D surface models from noisy sensor data. The method uses oriented probabilistic models of the measurement noise and combines them with feature-enhancing prior probabilities over 3D surfaces. When applied to surface reconstruction, the method simultaneously smooths noisy regions while enhancing features such as corners. When applied to surface decimation, it finds models that closely approximate the original mesh when rendered. The method is applied in the context of computer animation where it finds decimations that minimize the visual error even under nonrigid deformations.

A DTLS based end-to-end security architecture for the Internet of Things with two-way authentication

In this paper, we introduce the first fully implemented two way authentication security scheme for the Internet of Things (IoT) based on existing Internet standards, especially the Datagram Transport Layer Security (DTLS) protocol. The proposed security scheme is based on the most widely used public key cryptography (RSA), and works on top of standard low power communication stacks.We believe that by relying on an established standard, existing implementations, engineering techniques and security infrastructure can be reused, which enables easy security uptake. We present an implemented system architecture for the proposed scheme based on a low-power hardware platform suitable for the IoT. We further demonstrate its feasibility (low overheads and high interoperability) through extensive evaluation.

Face detection and tracking for video coding applications

In video communication applications at low bitrates, coding artifacts are especially disturbing in face areas. Encoding faces with higher quality than background regions requires automatic face detection. This paper presents a robust face segmentation and tracking algorithm and investigates the application to region-of-interest coding with H.263+ and object-based coding with MPEG-4.

Springbrook: Challenges in developing a long-term, rainforest wireless sensor network

We describe the design, development and learnings from the first phase of a rainforest ecological sensor network at Springbrook - part of a World Heritage precinct in South East Queensland. This first phase is part of a major initiative to develop the capability to provide reliable, long-term monitoring of rainforest ecosystems. We focus in particular on our analysis around energy and communication challenges which need to be solved to allow for reliable, long-term deployments in these types of environments.

Opal: A Multiradio Platform for High Throughput Wireless Sensor Networks

Design of current sensor network platforms has favored low power operation at the cost of communication throughput or range, which severely limits support for real-time monitoring applications with high throughput requirements. This letter presents the design of the versatile Opal platform that couples a Cortex M3 MCU with two IEEE 802.15.4 radios for supporting sensing applications with high transfer rates without sacrificing communication range. We present experiments that evaluate Opals throughput and range when operating with one or two radios, and we compare these results with an Iris-based node and TelosB nodes. We introduce the spatial energy cost metric that measures the energy to transfer one bit of information in a unit area for comparing the performance of the platforms. The results show that Opal operating with dual radios increases the throughput compared to single radio platforms with the same data-rate by a factor of 3.7, without sacrificing communication range. Opal operating with one radio can deliver a 460% increase in throughput over other single radio nodes at reduced range. We also analyze the implications of Opals design for multihop communication, showing that the dual radio architecture removes the bandwidth bottleneck in multihop communications that is inherent to single radio platforms.

Covariance analysis of motion-compensated frame differences

The second-order statistics of motion-compensated frame differences in a low-bit-rate hybrid video coding scheme with overlapped block motion compensation are investigated. Based on the empirical covariance sequence, an adequate compound covariance model is developed. The prediction gain for motion-compensated frame differences is evaluated, and the performance of the discrete cosine transform for interframe transform coding is discussed.

The Smart Skies project

The Smart Skies project is an ambitious and world-leading research endeavor exploring the development of key enabling technologies, which support the efficient utilization of airspace by manned and unmanned airspace users. This provides a programmatic description of the research and development of: an automated separation management system; a mobile aircraft tracking system; and aircraft-based sense-and-ad technologies. A summary of the results from a series of real-world flight testing campaigns is also presented.

Segmentation of human faces in color images using connected operators

In this paper we present a face segmentation algorithm for color images based on connected operators. Using a skin color model, we construct a skin probability image that indicates the probability of each pixel representing skin. Morphological filters are applied to this probability images instead of applying them to the original image. A hierarchy of operators with geometrical criteria (size, compactness, orientation) is employed to simplify the skin probability image and a gray level criterion based on principal components analysis is used for final classification. Using connected operators, regions with different probabilities of being skin are analyzed which leads to a more robust segmentation compared to a single threshold classification.