We present an overview of the field of anonymous communications, from its establishment in 1981 from David Chaum to today. Key systems are presented categorized according to their underlying principles: semi-trusted relays, mix systems, remailers, onion routing, and systems to provide robust mixing. We include extended discussions of the threat models and usage models that different schemes provide, and the trade-offs between the security properties offered and the communication characteristics

Modern vehicles are increasingly equipped with more sensors which are connected to control units through cables for transmitting crucial real-time sensing data. To reduce the complexity and cost brought to the automotive design and production by the sensor wiring harness, replacing cables with wireless links has been proposed in [1].With its fine capability of solving multipath fading and interference resilience, as well as its freely available spectrum, the ultra-wideband (UWB) technology is considered as a highly promising candidate for such intra-vehicle wireless network. For the purpose of evaluating UWB based sensor network, compared with wired system, from the aspects of performance and reliability in transmitting automotive sensing data, an UWB communication testbed is needed. In this paper we present our first attempt in building an intra-vehicle UWB wireless sensor network to transmit automotive speed data from four wheel speed sensors to the electronic control unit (ECU) 1. Assembly of the testbed consists of ABS motor control simulating system, wheel speed sensors, UWB transmitting nodes and the UWB network coordinator interfacing with ECU. The paper also includes the description of the main testbed software modules and the report of initial measurement result. Future measurement plan and further work needed to improve the testbed are discussed in the conclusion section. 1

Side-channel information leaks have been reported in various online applications, especially, in wireless local area networks (WLANs) due to the shared-medium nature of wireless links and the ease of eavesdropping. Even when Wi-Fi traffic is encrypted, its characteristics are identifiable, which can be used to infer sensitive user activities and data. Existing countermeasures do not offer effective and efficient protection: packet padding and traffic morphing often bring in substantial communication overheads; attempts to anonymize user identifiers are vulnerable to the analysis based upon traffic statistics, which allows the adversary to link traffic traces to individual users. In this paper, we present a new technique, called traffic demultiplexing, which offers effective protection against Wi-Fi traffic analysis without incurring noticeable overhead and performance degradation. Our approach utilizes Media Access Control (MAC) layer virtualization and packet scheduling over multiple virtual MAC interfaces to shape the traffic on each virtual MAC interface, so as to hide the original traffic characteristics. Different from the higher-layer defensive approaches designed for specific applications, traffic demultiplexing operates at the MAC layer and therefore provides a general defense for various applications. In addition, it is transparent to users and other protocol stacks. We implemented our technique over Multiband Atheros Driver for Wi-Fi (MadWifi) and evaluated it in real WLAN environments. Our experimental study demonstrates that traffic demultiplexing is effective and efficient in defending against traffic analysis attacks and also easy to deploy. 1

We present an overview of the field of anonymous communications, from its establishment in 1981 by David Chaum to today. Key systems are presented categorized according to their underlying principles: semitrusted relays, mix systems, remailers, robust & verifiable mixes, and onion routing systems. We include extended discussions of the threat models and usage models that different schemes provide, and the tradeoffs between the security properties offered and the communication characteristics