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Authentication via fingerprint embedding at the physical layer utilizes noise in the wireless channel to attain a certain degree of information theoretic security that traditional HMAC methods cannot provide. Fingerprint embedding refers to a key-aided process of superimposing a low-power tag to the primary message waveform for the purpose of authenticating the transmission. The tag is uniquely created from the message and key and successful authentication is achieved when the correct tag is detected by the receiver. This paper generalizes a framework for embedding physical layer fingerprints to create an authenticated side-channel for minimal cost. Side-channel information is conveyed to the receiver through the transmitter’s choice of tag from a secret codebook generated by the primary message and a shared secret key. In addition, a new linear coding scheme is introduced which enhances the ability to trade off the performance goals of authentication, side-channel rate, secrecy, and privacy. [ABSTRACT FROM PUBLISHER]

Authentication is a fundamental requirement for secure communications. In this article, we describe a general framework for fingerprint embedding at the physical layer in order to provide message authentication that is secure and bandwidth-efficient. Rather than depending on channel or device characteristics that are outside of our control, deliberate fingerprint embedding for message authentication enables control over performance trade-offs by design. Furthermore, low-power fingerprint designs enhance security by making the authentication tags less accessible to adversaries. We define metrics for communications and authentication performance, and discuss the trade-offs in system design. Results from our wireless software-defined radio experiments validate the theory and demonstrate the low complexity, practicality, and enhanced security of the approach. [ABSTRACT FROM PUBLISHER]

The lower VHF band has potential for low-power, short-range communications, as well as for geolocation applications, in both indoor and urban environments. Most prior work at low VHF focuses on longer range path loss modeling, often with one node elevated. In this paper, we study indoor/outdoor near-ground scenarios through experiments and electromagnetic wave propagation simulations. These include the effects of indoor penetration through walls and obstacles, as well as indoor/outdoor cases, for both line of sight (LoS) and nonLoS (NLoS), at ranges up to 200 m. Mounting our receiver (Rx) on a robotic platform enabled the collection of thousands of measurements over an extended indoor/outdoor test area. We measure the channel transfer function, employing bandpass waveform sampling, with pulse and tone probe signals. Based on statistical tests, we show that the measured channels have a nearly ideal scalar attenuation and delay transfer function, with minimal phase distortion, and little to no evidence of multipath propagation. Compared with higher VHF and above, the measured short-range VHF channels do not exhibit small-scale fading, which simplifies communications Rx signal processing, and enables phase-based geolocation techniques. [ABSTRACT FROM PUBLISHER]

We consider authentication of a wireless multiple-input–multiple-output (MIMO) system by deliberately introducing a stealthy fingerprint at the physical layer. The fingerprint is superimposed onto the data and uniquely conveys an authentication message as a function of the transmitted data and a shared secret key. A symbol synchronous approach to fingerprint embedding provides low complexity operation. In comparison with a conventional tag-based authentication approach, fingerprinting conveys much less information on the secret key to an eavesdropper. We study the trade-offs between stealth, security, and robustness, and show that very good operating points exist. We consider the cases when deterministic or statistical channel state information is available to the transmitter, and show how precoding and channel mode power allocation can be applied to both the data and the fingerprint in combination to enhance the authentication process. [ABSTRACT FROM PUBLISHER]