Group Secret Key Generation via Received Signal Strength: Protocols, Achievable Rates, and Implementation

Abstract

Abstract-Secret key generation among wireless devices using physical layer information of radio channel has been an attractive alternative for ensuring security in mobile environments. Received signal strength (RSS) based secret key extraction gains much attention due to its easy accessibility in wireless infrastructure. However, the problem of using RSS to generate keys among multiple devices to ensure secure group communication in practice remains open. In this work, we propose a framework for collaborative key generation among multiple wireless devices leveraging RSS. To deal with mobile devices not within each other's communication range, we employ relay nodes to achieve reliable key extraction. To enable secure group communication, two protocols are developed to perform collaborative group key generation via star and chain topologies respectively. We further provide the theoretic analysis on the achievable secrecy rate for both star and chain topologies in the presence of an eavesdropper. Our prototype development using MICAz motes and extensive experiments using fading trend based key extraction demonstrate the feasibility of using RSS for group key generation in both indoor and outdoor environments, and concurrently achieving a lower bit mismatch rate compared to existing studies.

Verification of Key Generation from Individual OFDM Subcarrier's Channel Response

“…Therefore, randomness is the most important feature of the generated key sequence. We use National Institute of Standards and Technology (NIST) randomness test suite [27] to verify the randomness of the key sequence, which is also used by many other researchers [9], [10], [12], [13], [18].…”

“…There have been several practical key generation systems reported, employing IEEE 802.11 [9]- [14], IEEE 802.15.4 [15]- [18], ultrawideband (UWB) [19], TV and radio signals [20]. IEEE 802.11 is the most widely adopted wireless technique in key generation due to its widespread application in our daily life.…”

“…Wireless sensor networks (WSNs) are another hot application area of key generation [15]- [18]. The CC2420 is a 2.4 GHz IEEE 802.15.4 compliant RF transceiver and widely used in WSN nodes, such as MicaZ and TelosB.…”

Comparative simulation for physical layer key generation methods

“…Recent researches have turned attentions to quantum cryptography using physical layer characteristics, such as channel and noise measurement, as a source of randomness to generate the secret keys [7]- [17]. As an example, [7] used RSS for key generation in indoor and outdoor environments with lower Bit Mismatch Rate (BMR).…”

Group Secret Key Generation in Wireless Networks: Algorithms and Rate Optimization

“…Since then, several tree-based algorithms have been developed to achieve the group secret key capacity for the multi-terminal pairwise independent network (PIN) [11]- [15]. On the other hand, effective group key generation algorithms have been proposed for wireless networks by exploiting channel characteristics in [28]- [30]. These algorithms are more practical for real systems at the expense of some scarification in the group key rate.…”