On the Security of Key Extraction From Measuring Physical Quantities

Abstract

Abstract-Key extraction via measuring a physical quantity is a class of information theoretic key exchange protocols that rely on the physical characteristics of the communication channel, to enable the computation of a shared key by two parties that share no prior secret information. The key is supposed to be information theoretically hidden to an eavesdropper. Despite the recent surge of research activity in the area, concrete claims about the security of the protocols typically rely on channel abstractions that are not fully experimentally substantiated. In this work, we propose a novel methodology for the experimental security analysis of these protocols. The crux of our methodology is a falsifiable channel abstraction that is accompanied by an efficient experimental approximation algorithm of the conditional minentropy available to the parties given the view of the eavesdropper.We focus on the signal strength between two wirelessly communicating transceivers as the measured quantity and we use an experimental setup to compute the conditional min-entropy of the channel given the view of the attacker which we find to be linearly increasing. Armed with this understanding of the channel, we showcase the methodology by providing a general protocol for key extraction in this setting that is shown to be secure for a concrete parameter selection. In this way we provide a comprehensively analyzed wireless key extraction protocol that is demonstrably secure against passive adversaries assuming our falsifiable channel abstraction. Our use of hidden Markov models as the channel model and a dynamic programming approach to approximate conditional min-entropy might be of independent interest, while other possible instantiations of our methodology can be feasible and may be motivated by this work.

Authenticated key establishment for low-resource devices exploiting correlated random channels

“…[6] -A multitude of open research questions are formulated in recent works [3,4,5,6,8], all wondering about open, unaddressed issues in previous security analyses and adversarial models of physical-layer security schemes. We collect and address all these questions and present the first pairing protocol tailored for low-cost resourceconstrained wireless platforms and resistant against strong, active attackers.…”

“…syndrome-based secure sketch with BCH codes as proposed in [29] for reconciliation and [5]. Here, we consider a (255, 131, 37)-BCH code.…”

On Performance Analysis of Protective Jamming Schemes in Wireless Sensor Networks

“…We roughly categorize them into three types: (i) lightweight encryption schemes [21,22,23,24]; (ii) generating artificial noise to limit the amount of information that can be extracted by eavesdroppers [25,26,27]; and (iii) mitigating the eavesdropping risk by controlling the transmitting power [28]. Table 1 summarizes these schemes.…”

“…Table 1 summarizes these schemes. In particular, a number of lightweight encryption schemes based on physical layer features of wireless networks have been proposed [21,22,23,24]. The main idea of physical-layer encryption schemes is to exploit the inherent randomness of communication channels so that the amount of information that can be extracted by an eavesdropper is mitigated.…”

Security Analysis of Quantization Schemes for Channel-based Key Extraction

“…Also, lossy schemes need to communicate to select samples and increase the robustness of their key generation. However, Edman et al [6] stated that such reconciliation requires interaction that may result in potentially zeroing the conditional entropy 3 and Eberz et al [5] successfully attacked a guard-band-based quantization scheme, demonstrating that strong characteristics may be observed by a passive adversary.…”