Mutual random phase injection can be considered an appropriate solution for tackling the low key generation rate issue in physical layer key generation schemes. In this paper, the confidentiality of a phase-based group secret key generation scheme has been analyzed by employing a geometric secrecy approach in a static environment. Accordingly, we exploit this approach to achieve some common randomness quantities in our group model. For this purpose, the process of key generation is defined for a star topology. Next, both vulnerability and secrecy regions are identified. To address the challenge of security vulnerability in non-proximity areas due to the spatial correlation in static environments with dominant line-of-sight (LoS), multiple carrier frequencies have been employed at the channel probing stage to enhance the secrecy regions. Finally, the key error probability is provided not only to establish an appropriate evaluation of the quality of the generated keys but also to show the efficiency of our proposed scheme in comparison with previous works.
Mutual random phase injection can be considered an appropriate solution for tackling the low key generation rate issue in physical layer key generation schemes. In this paper, the confidentiality of a phase-based group secret key generation scheme has been analyzed by employing a geometric secrecy approach in a static environment. Accordingly, we exploit this approach to achieve some common randomness quantities in our group model. For this purpose, the process of key generation is defined for a star topology. Next, both vulnerability and secrecy regions are identified. To address the challenge of security vulnerability in non-proximity areas due to the spatial correlation in static environments with dominant line-of-sight (LoS), multiple carrier frequencies have been employed at the channel probing stage to enhance the secrecy regions. Finally, the key error probability is provided not only to establish an appropriate evaluation of the quality of the generated keys but also to show the efficiency of our proposed scheme in comparison with previous works.
Given the inherent constraint of low key generation rates in physical layer key generation schemes, mutual random phase injection is considered a viable solution for establishing common randomness quantities among legitimate nodes. This paper analyzes the confidentiality of a phase-based group key generation scheme for uncrewed aerial vehicle (UAV) communications, which is designed for a star topology and evaluated in a static environment. To this end, a geometric secrecy approach is utilized to determine both vulnerability and secrecy regions, incorporating a variety of eavesdropping strategies for a comprehensive analysis. In static environments characterized by a dominant line of sight (LoS), spatial correlation presents a security vulnerability in non-proximity regions. This issue is addressed using multiple carrier frequencies during the channel probing stage to enhance the secrecy regions. Accordingly, the extent of vulnerability regions is substantially affected by the selected carrier frequencies and the intervals between them. Furthermore, the analysis determined the significant dependence of the system’s optimal performance on the number of legitimate nodes and their spatial layouts. The performance of the proposed scheme is evaluated by analyzing both the required number of time slots for key generation and the bit mismatch rate (BMR), which is introduced to measure the quality of the generated keys. Moreover, the analysis confirms the randomness of the generated bit sequences via the NIST test suite and highlights the high scalability of our approach compared to existing work.
In secret key generation (SKG), both communicating parties require access to a reciprocal entropy source. Free-space communication fails to provide this due to its strong line-of-sight (LoS) link and absence of multipath scattering. In general, in a free-space environment, SKG faces two primary challenges: a low key generation rate (KGR) and heightened security threats due to a lack of spatial decorrelation. In static free-space environments, the lack of temporal variation further exacerbates challenges. This paper aims to identify and enhance techniques from SKG literature to enable a location-based approach for secure key establishment. Important solutions include exploiting channel phase information as a common measurable parameter, adopting mutual random phase injection to involve the eavesdropper in the eavesdropping process while improving KGR, and introducing geometric secrecy as a security evaluation framework. A principal design objective in geometric secrecy is reducing the vulnerability region to restrict eavesdropping opportunities. To accomplish this, we propose a cooperative key generation (CKG) scheme to shrink this region. In our proposed CKG scheme, the sampling time is primarily governed by the switching time between transmit and receive modes. For information reconciliation, a selection algorithm for a shortened Bose–Chaudhuri–Hocquenghem (SBCH) code is proposed, and SBCH combined with a cyclic redundancy check (CRC) corrects bit mismatches. Worst-case channel sampling and information reconciliation leakage rates are analyzed. The leftover hash lemma is applied during privacy amplification to render leaked information useless. Simulation results indicate that the proposed CKG scheme achieves enhanced effectiveness with increased the number of quantization levels, while a wider angular guard zone plays a critical role in improving the KGR.
Recently, there has been great interest in physical layer security techniques that exploit the randomness of wireless channels for securely extracting cryptographic keys. Several interesting approaches have been developed and demonstrated for their feasibility. The state-of-the-art, however, still has much room for improving their practicality. This is because i) the key bit generation rate supported by most existing approaches is very low which significantly limits their practical usage given the intermittent connectivity in mobile environments; ii) existing approaches suffer from the scalability and flexibility issues, i.e., they cannot be directly extended to support efficient group key generation and do not suit for static environments. With these observations in mind, we present a new secret key generation approach that utilizes the uniformly distributed phase information of channel responses to extract shared cryptographic keys under narrowband multipath fading models. The proposed approach enjoys a high key bit generation rate due to its efficient introduction of multiple randomized phase information within a single coherence time interval as the keying sources. The proposed approach also provides scalability and flexibility because it relies only on the transmission of periodical extensions of unmodulated sinusoidal beacons, which allows effective accumulation of channel phases across multiple nodes. The proposed scheme is thoroughly evaluated through both analytical and simulation studies. Compared to existing work that focus on pairwise key generation, our approach is highly scalable and can improve the analytical key bit generation rate by a couple of orders of magnitude.
With the increasing demands for sharing confidential information among massive Internet of Things (IoT) devices in 5G and beyond wireless networks, many applications require the common secret key generation for a group of IoT devices. However, most of the existing works on physical layer secret key generation (PLKG) only focus on the pairwise key generation between two users, which is a low efficient and high cost to be extended to the scenarios of group key generation. In this work, we propose a new efficient multiple-input–multiple-output (MIMO) physical layer group secret key generation scheme to reduce the consumption of channel probing and improve the efficiency for group key generation. Different from current schemes, in the proposed scheme, the transmitter randomly generates the group secret key and directly broadcasts the downlink data symbols to the group users. At the receiver end, each group user can efficiently “observe” the common group key through the downlink broadcasting data symbols, while keeping perfect secrecy of the shared group key against eavesdroppers. The performance of reliability, security, and the group key generation rate is fully investigated, which shows the advantages of high efficiency, low consumption, and strong robustness of the proposed scheme. Extensive simulations are conducted to validate the effectiveness of the proposed scheme.
Physical layer secret key generation exploits the inherent randomness of wireless channels. However, for wireless channels with long coherence time, key generation rate can be extremely low due to lack of randomness in channels. In this paper, a novel key generation scheme is proposed for a general wireless network where channels are static and each transmitter is equipped with two antennas. It integrates opportunistic beamforming and frequency diversity to achieve fast secret key generation. In this scheme, channel fluctuations are first induced by controlling amplitude and phase of each symbol in the training sequence on each antenna. Thus, key generation rate is significantly increased. However, the induced channel fluctuations lead to correlation between the legitimate channel and the eavesdropping channel, which compromises key secrecy. To this end, frequency diversity is then exploited to ensure that key secrecy grows with the key size. The secret key generation scheme is investigated in both narrowband and wideband systems, and its performance is evaluated through both theoretical analysis and simulations. Performance results have validated randomness and secrecy of secret keys and also illustrate that the proposed scheme can generate secret keys at a rate of 2Kb/s for narrowband systems and 20Kb/s for wideband systems.
Physical layer secret key generation exploits the reciprocal channel randomness for key generation and has proven to be an effective addition security layer in wireless communications. However, static or scarcely random channels require artificially induced dynamics to improve the secrecy performance, e.g., using intelligent reflecting surface (IRS). One key challenge is that the induced random phase from IRS is also reflected in the direction to eavesdroppers (Eve). This leakage enables Eve nodes to estimate the legitimate channels and secret key via a globally known pilot sequence. To mitigate the secret key leakage issue, we propose to exploit random matrix theory to inform the design of a new physical layer secret key generation (PL-SKG) algorithm. We prove that, when sending appropriate random Gaussian matrices, the singular values of Alice's and Bob's received signals follow a similar probability distribution. Leveraging these common singular values, we propose a random Gaussian matrix based PL-SKG (RGM PL-SKG), which avoids the usages of the globally known pilot and thereby prevents the aforementioned leakage issue. Our results show the following: (i) high noise resistance which leads to superior secret key rate (SKR) improvement (up to 300%) in low SNR regime, and (ii) general improved SKR performance against multiple colluded Eves. We believe our combination of random matrix theory and PL-SKG shows a new paradigm to secure the wireless communication channels.