Secret Key Generation Scheme Research Articles

A secure data transmission framework for IoT enabled healthcare

The Internet of Medical Things (IoMT) has transformed healthcare by connecting medical devices, sensors, and patients, significantly improving patient care. However, the sensitive data exchanged through IoMT is vulnerable to security attacks, raising serious privacy concerns. Traditional key sharing mechanisms are susceptible to compromise, posing risks to data integrity. This paper proposes a Timestamp-based Secret Key Generation (T-SKG) scheme for resource-constrained devices, generating a secret key at the patient's device and regenerating it at the doctor's device, thus eliminating direct key sharing and minimizing key compromise risks. Simulation results using MATLAB and Java demonstrate the T-SKG scheme's resilience against guessing, birthday, and brute force attacks. Specifically, there is only a 9 % chance of key compromise in a guessing attack if the attacker knows the key sequence pattern, while the scheme remains secure against brute force and birthday attacks within a specified timeframe. The T-SKG scheme is integrated into a healthcare framework to securely transmit health vitals collected using the MySignals sensor kit. For confidentiality, the Data Encryption Standard (DES) with various Cipher Block modes (ECB, CBC, CTR) is employed.

A new practical physical layer secret key generation in the presence of an untrusted relay

Physical layer secret key generation (SKG) has recently been introduced as a lightweight and efficient solution for sixth-generation (6G) networks. In this area, schemes based on local random generators are used for high-rate key generation. One of these schemes is random phase injection, where channel probe signals with random phases are exchanged between communication parties (source and destination). This paper proposes an SKG scheme in the presence of an untrusted relay, which helps the SKG process while cannot extract the secret key. To make the scheme operational, for the first time, the channel probe signals are considered discrete random phase based on M-PSK signals and a multi-bit quantizer is used in the reception. In addition, to reduce the key error rate, quantization with guard bands (GB) is used for key extraction. For such a scenario, we derive expressions for key agreement rate, key mismatch rate (KMR), key discarding rate (KDR) and key generation rate (KGR). Additionally, for the first time, this work examines the context of geometric secrecy for the proposed discrete phase key generation scheme for both direct and relaying scenarios. Through simulations, several engineering insights are presented to enhance the quality of the proposed SKG and its security.

A Channel Frequency Response-Based Secret Key Generation Scheme in In-Band Full-Duplex MIMO-OFDM Systems

Physical layer-based secret key generation (PHY-SKG) schemes have attracted significant attention in recent years due to their lightweight implementation and ability to achieve information-theoretical security. In this paper, we study a channel frequency response (CFR)-based SKG scheme for in-band full-duplex (IBFD)-multi-input and multi-output (MIMO) systems. We formulate the intrinsic practical imperfections and derive their effects on the probing errors. Then we derive closed-form expressions for the secret key capacity (SKC) in the presence of a passive eavesdropper accordingly. We analyze the asymptotic behavior of the SKC in the high-SNR regime and reveal the fundamental limits for IBFD and HD probing. Based on the asymptotic SKC, we investigate the conditions under which IBFD can outperform HD. Numerical results illustrate that effective analog self-interference cancellation (ASIC) depth is the basis for IBFD probing to gain benefits over HD. Finally, we analyze the properties of the collected samples of the CFR-based SKG scheme and propose an averaging pre-processing and a segmental quantization, which reduce the key disagreement rate and remove the effects of large-scale fading to guarantee randomness. 3GPP specification-based simulations and the National Institute of Standards and Technology (NIST) test suite verify the theoretical analysis and the effectiveness of the proposed SKG scheme.

Implementation of Secret Key Generation on Mobile Crowdsensing Application to Secure Tracking Location of Motorcyclists

Mobile crowdsensing is a method for collecting many data from sensors on smartphone. In this research, mobile crowdsensing application will be developed to display location of motorcyclits who connected in an Ad-Hoc network along with a security system using the Secret Key Generation (SKG) scheme to generate a secret key that will be used to encrypt and decrypt the data. From the results it can be concluded that the highest measurement correlation is 0.0398 and the lowest is 0.0018 but after randomness extraction proccess, the highest correlation is 0.996 and the lowest is 0.978. After encryption, information of Alice and Bob is stored as random character in database and decrypted as plaintext as shown as in application. In the attacking result, the data after encrypted just shown random character in traffic monitor. When the eavesdroppers manipulate its IP address like Alice's, they can’t connect to Bob.

Physical Layer Key Generation for Secure OAM Communication Systems

In this paper, we propose a physical layer secret key (PLSK) generation scheme for secure encrypted transmissions in orbital angular momentum (OAM) communication systems which improves the secret key capacity via taking advantage of OAM orthogonal modes. Based on the line-of-sight (LoS) quasi-static channel conditions in OAM systems, we propose a mode-based active defense phase in the PLSK scheme to invalidate keys generated by an eavesdropper when it is extremely close to the legitimate user. Our simulation results highlight that the key information generated by the eavesdropper is almost zero in the case of highly correlated legitimate and eavesdropping channels under LoS conditions. In addition, our proposed OAM PLSK scheme achieves a higher key generation rate (KGR) than existing works since mode-based active defense can disrupt the process of PLSK by the eavesdropper.

Sharing Secrets via Wireless Broadcasting: A New Efficient Physical Layer Group Secret Key Generation for Multiple IoT Devices

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.

A one-time pad encryption scheme based on efficient physical-layer secret key generation for intelligent IoT system

The one-time pad (OTP) is an application-layer encryption technique to achieve the information-theoretic security, and the physical-layer secret key generation (SKG) technique is a promising candidate to provide the random keys for OTP. In this paper, we propose a joint SKG and OTP encryption scheme with the aid of a reconfigurable intelligent surface (RIS) to boost secret key rate. To maximize the efficiency of secure communication, we divide the process of secure transmission into two stages: SKG and then encrypted packet transmission. Meanwhile, we design an optimal algorithm for allocating time slots for SKG to maximize SKG efficiency without security risk. Furthermore, we design a key updating protocol based on our SKG scheme for OTP encryption. Simulation results verify that our scheme can generate keys securely and efficiently, and significantly improve the secure communication performance in an intelligent IoT system.

Performance Improvement of Secret Key Generation Scheme in Wireless Indoor Environment

The Secret Key Generation (SKG) scheme that exploits the reciprocity and uniqueness of wireless channel between two users plays a significant part in a new increasing distributed security system. The scheme performance can be distinguished based on the low value of Key disagreement Rate (KDR), the high value of Key Generation Rate (KGR), as well as the fulfillment of the NIST randomness standard. The previous SKG scheme has a high KDR due to a direct quantization of a measurement result of the Received Signal Strength (RSS). To overcome the above issue, we conduct a pre-processing of measurement result before quantization with the Kalman method. The pre-process is carried out to improve the channel reciprocity between two legitimate users with the objective to reduce the bit mismatch. Through an experiment, we propose a new quantization scheme called a Modified Multi-Bit (MMB) that uses a multi-bit system on every level of quantization. The test results show that the proposed combination of preprocessing and the MMB scheme has a better performance compared to the existing schemes in terms of KDR and KGR. The Secret Key generated by our scheme also fulfills the NIST randomness standard.

Hardware-Impaired PHY Secret Key Generation With Man-in-the-Middle Adversaries

In this letter, we examine the PHY layer secret key generation (PHY-SKG) scheme in the presence of man-in-the-middle (MiM) adversary, while legitimate parties suffer from <i>hardware impairments</i> (HIs). Different from previous works on PHY-SKG that consider adversaries who simply try to make an interference in the communication link, the MiM aims to deceive legitimate entities about the source of common randomness. To conquer the MiM attack, legitimate parties utilize randomized pilots (RPs) in our proposed scheme. We analyze the effect of HIs on the performance of system by deriving the achievable secret key rate (SKR). Our results highlight a fundamental limit, as a ceiling phenomena, on the SKR when having practical imperfections. Top-level guidelines for selecting impairment levels along the transceiver chains is also provided to maximize the performance of the PHY-SKG protocol. Our numerical results verify the analytic expressions derived, while providing insights on system design. We show that by properly considering the HIs, about 25&#x0025; improvement in the SKR is achievable.

LoRa-LiSK: A Lightweight Shared Secret Key Generation Scheme for LoRa Networks

Physical-layer security (PLS) schemes use the randomness of the channel parameters, namely, channel state information (CSI) and received signal strength indicator (RSSI) to generate the secret keys. There has been limited work in PLS schemes in long-range (LoRa) wide-area networks (LoRaWANs) which hinder their widespread application. Limitations observed in existing studies include the requirement of high correlation between channel parameter measurements for secret key generation in the proposed schemes and the evaluation of the schemes has only been done in either fully indoor or outdoor environments. The real-world wireless sensor networks (WSNs) and LoRa use cases might not meet both requirements thus making the current PLS schemes inappropriate for these systems. By considering the limitations found in existing PLS schemes, this article proposes LoRA-LiSK, a practical and efficient shared secret key generation scheme for LoRa networks. Our proposed LoRa-LiSK scheme consists of several preprocessing techniques (timestamp matching, two sample Kolmogorov–Smirnov tests, and a Savitzky–Golay filter), multilevel quantization, information reconciliation using Bose–Chaudhuri–Hocquenghem (BCH) codes, and finally, privacy amplification using secure hash algorithm SHA-2. The LoRa-LiSK scheme is extensively evaluated on real WSN/IoT devices in practical application scenarios: 1) indoor to outdoor and 2) LoRa static and mobile outdoor links. It outperforms existing schemes by generating keys with channel parameter measurements of low correlation values (0.2–0.6), while still essentially achieving high key generation rates, and low key disagreement rates (10%–20%). The scheme updates a key in approximately 1 h using an application profile with high transmission rate compared to 3 h reported by existing works while still respecting the duty cycle regulation. It also incurs less communication overhead compared to the existing works.

Secret key generation scheme based on RIS antenna for static environments

A conventional secret key generation scheme achieves a low secret key rate in static environments. To solve this problem, the reconfigurable intelligent surface (RIS) antenna is merged with the device at the base station and is firstly proposed for secret key generation. By tuning the phase shifts at the RIS, a random varying beam can be generated and combined with the original wireless channel to form a new equivalent channel so that the key capacity is not subject to the time variance of the wireless channel. Then the closed-form solution is derived. Theoretical analysis and simulation show that the performance can be increased to that of a fast varying channel with limited radiating units. Moreover, the proposed scheme is superior to the existing schemes, in which the RIS is used as a reflective surface, over performance gain and preventing information disclosure. To further develop the gain of RIS, a joint design scheme is proposed, where some units are used for key generation, and some units are used for beamforming. Finally, the joints closed-form solution scheme is derived. Finally, on the basis of satisfying the key capacity and communication performance, an optimal resource allocation strategy is proposed. Simulation results illustrate that the key capacity and communication performance can be improved simultaneously.

Half-Duplex Mode-Based Secure Key Generation Method for Resource-Constrained IoT Devices

The physical layer secret key generation scheme is a preferred solution designed for resource-constrained Internet of Things (IoT) devices. But it suffers from a severe attack, the signal manipulating attack, which aims at controlling the generated key. The existing solutions either cannot prevent all kinds of signal manipulation attacks or require working in full-duplex mode, which is not suitable for resource-constrained IoT devices. In this article, we introduce a secret key generation scheme with the help of an untrusted relay to address this dilemma. Also, our method can protect the privacy of legitimate users from the untrusted relay. We conclude a general signal manipulation attack model from existing practical signal manipulation attacks and analyze the security strength and privacy preserving ability of our scheme based on this model. Finally, we compare our method with existing signal manipulation attack solutions. The result shows that our method is the best solution for resource-constrained IoT systems.

Physical-Layer Secret Key Generation in Power Line Communication Networks

Due to the inherent broadcast nature, power line communication (PLC) is vulnerable to eavesdropping. Traditionally, the secret keys are generated/distributed by pre-shared keys, adaptive tone mapping, or asymmetric encryption algorithm. All of these methods face problems such as high computational complexity, high cost, or less security. To solve the problem, a physical layer security (PLS)-based secret key generation (SKG) scheme aiming at the typical in-home broadband PLC network is proposed in this paper. However, the slowly time-varying characteristic and the serious noise interference in PLC channels will degrade the performance of the PLS-based SKG scheme. To break through the limitation of the randomness of PLC channels, two-way random signals are introduced. To make the SKG system more resistant to noise, the channel frequency response-based adaptive quantization (CFR-AQ) algorithm is designed, in which the amplitude threshold and the quantization level are adaptive to the noise power and the target key disagreement rate (KDR) to maximize the key generation rate (KGR). The performance is analyzed in two scenarios: single eavesdropper and multiple eavesdroppers. The simulation results demonstrate that the proposed scheme has a good overall performance in terms of KDR, KGR, and security with a lower complexity in the presence of single or multiple non-collusive eavesdroppers, and it can be regarded as an alternative solution to generate secret keys in PLC networks.

Intelligent Reflecting Surface-Assisted Secret Key Generation With Discrete Phase Shifts in Static Environment

Physical layer secret key generation is a promising candidate to achieve one-time-pad encryption approach for the wireless communication system. However, in a static environment, the secret key rate is low due to the lack of channel time-variation. To solve this problem, this letter proposes a novel secret key generation scheme assisted by an intelligent reflecting surface with discrete phase shifts. In the scheme, legitimate nodes construct the dynamic time-varying channel by rapidly and randomly switching the phase of IRS elements. Then, channel coefficients are used to generate the secret key. Based on the IRS channel model, we derive the probability distribution of the channel coefficient and the expressions of the secret key rate. Furthermore, we optimize the secret key rate by adjusting the switching time of the IRS phase. Monte Carlo simulation and numerical results show that our proposed scheme can update the secret key in a static environment.

Protecting Physical Layer Secret Key Generation from Active Attacks.

Lightweight session key agreement schemes are expected to play a central role in building Internet of things (IoT) security in sixth-generation (6G) networks. A well-established approach deriving from the physical layer is a secret key generation (SKG) from shared randomness (in the form of wireless fading coefficients). However, although practical, SKG schemes have been shown to be vulnerable to active attacks over the initial “advantage distillation” phase, throughout which estimates of the fading coefficients are obtained at the legitimate users. In fact, by injecting carefully designed signals during this phase, a man-in-the-middle (MiM) attack could manipulate and control part of the reconciled bits and thus render SKG vulnerable to brute force attacks. Alternatively, a denial of service attack can be mounted by a reactive jammer. In this paper, we investigate the impact of injection and jamming attacks during the advantage distillation in a multiple-input–multiple-output (MIMO) system. First, we show that a MiM attack can be mounted as long as the attacker has one extra antenna with respect to the legitimate users, and we propose a pilot randomization scheme that allows the legitimate users to successfully reduce the injection attack to a less harmful jamming attack. Secondly, by taking a game-theoretic approach we evaluate the optimal strategies available to the legitimate users in the presence of reactive jammers.

A Method for Detecting Amplitude-Phase Joint Characteristic Parameters of Wireless Channel for Generating Key Parameters

Aiming at the problems of poor adaptability and low secret key generation rate of secret key generation scheme based on single characteristic parameter of wireless channel, a secret key generation method based on joint characteristic parameters of amplitude and phase of wireless channel is proposed. This method is based on the single-eavesdropping wireless fading channel model; the joint characteristic model of amplitude and phase of wireless fading channel is established; it detects and extracts the joint characteristic parameters of amplitude and phase of channel, and then the proposed characteristics are quantified by using the equal probability joint quantization strategy of amplitude and phase to generate the secret key random parameters. In this paper, the amplitude and phase joint feature parameter detection method of wireless channel can not only improve the generation rate of random secret key parameters but also make the eavesdropping party’s eavesdropping error rate closer to 0.5. The test results show that the proposed scheme can significantly improve the rate, reliability, and security of generating key random parameters.

Efficient secret key generation scheme of physical layer security communication in ubiquitous wireless networks

This paper focuses on high efficiency secret key generation mechanism of physical-layer communication over fading channels in ubiquitous wireless networks. The secret key rate via traditional physical-layer approach could be limited when the wireless propagation channels connecting two sensors change slowly. To generate a high-rate secret key and improve the communication efficiency over quasi-static block fading channels, a novel multi-randomness device-to-device secret key generation strategy and a cooperative communication mechanism aided by relay nodes are proposed. In the proposed schemes, the legitimate members to send random signals rotationally in every coherent time T are set; thus, two legitimate ubiquitous wireless network members, Alice and Bob, can obtain the potential correlated information by exploiting the randomness and the reciprocity of the wireless propagation channels. Considering the reciprocity of wireless channels is variable while the forward channel gain and backward channel gain are correlated in coherent time, a modified secret key generation scheme is proposed via layered coding with theoretical secret key rates derived. The simulation results show that the proposed scheme outperforms traditional approaches with favourable application prospects in ubiquitous wireless communications networks and internet of things.

Secret Key Generation by Exploiting Traffic Load for Mobile Adhoc Networks

Nowadays the security assurance of information in Mobile Adhoc Networks (MANETs) is achieved by using secret keys. The dynamic and unpredictable nature of the network places challenges before the researchers in developing a suitable key generation method. Many of the present-day works aim at identifying passive attackers in the network and to protect the information from them. Active attackers are still posing difficulties in effective communication over Adhoc network. This paper proposes a point to point secret key generation scheme with the metadata traffic load suitable for Dynamic Source Routing (DSR) based MANETs. This work aims to extract correlated random data from the routing information and traffic matrix to develop a secret key and to study the effectiveness of this in identifying passive and active attackers. This scheme also ensures an optimum packet overhead and less computational complexity.

Channel covariance matrix based secret key generation for low‐power terminals in frequency division duplex systems

The existing secret key generation (SKG) techniques are not applicable for frequency division duplex (FDD) Internet of Things networks due to the low power constraints and limited computing resources. This letter proposes a SKG scheme based on the channel covariance matrix in FDD systems. First of all, a novel algorithm is proposed for inferring the downlink channel covariance matrix from the observed uplink channel covariance matrix with the aid of the transformation matrix. Then, a complete SKG scheme for low-power terminals in FDD systems is designed to generate keys from the downlink channel covariance matrix. Finally, simulation results show that this scheme can generate high-agreement secret keys in FDD systems. Compared with the loopback mechanism-based SKG scheme, this scheme is suitable for low-power terminals and can achieve significant performance improvement in terms of the key disagreement ratio.

On Quantization for Secret Key Generation From Wireless Channel Samples

Physical layer security (PLS) techniques hold promise for augmenting secure communications in the 5 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> generation of mobile wireless networks. Secret key generation (SKG) is a PLS technique which exploits the wireless propagation channel's randomness to generate symmetric key bits for information encryption and decryption. This work proposes symmetric key generation based on non-uniform quantization of the received signal strength (RSS) samples of a Nakagami-$m$ fading channel. The proposed strategy for non-uniform quantization for SKG aims to set quantization thresholds for maximal key randomness and high values of key generation rate (KGR) and key agreement probability (KAP). Finally, a framework is proposed to use single node RSS measurements, readily available in the literature, to generate RSS samples at the other link end. This framework facilitates the testing of new SKG algorithms that require simultaneous RSS measurements by the legitimate nodes, which are not readily available in the open literature. The effectiveness of the proposed SKG scheme is validated through Monte Carlo methods and the National Institute of Standards and Technology (NIST) test suite for assessing the randomness of the generated key sequence.