Secret Key Establishment Research Articles

Numerical security analysis of the three-state quantum key distribution protocol with realistic devices

Quantum key distribution (QKD) is a secure communication method that utilizes the principles of quantum mechanics to establish secret keys. The central task in the study of QKD is to prove security in the presence of an eavesdropper with unlimited computational power. In this work, we successfully solve a long-standing open question of the security analysis for the three-state QKD protocol with realistic devices, i.e., the weak coherent-state source. We prove the existence of the squashing model for the measurement settings in the three-state protocol. This enables the reduction of measurement dimensionality, allowing for key rate computations using the numerical approach. We conduct numerical simulations to evaluate the key rate performance. The simulation results show that we achieve a communication distance of up to 200 km.

Orbit design of satellite quantum key distribution constellations in different ground stations networks

In the field of Cryptography, Quantum Key Distribution (QKD) is an application of Quantum Information theory that obtained a great deal of attention in recent years. It allows to establish secret keys between two or more parties, in a much safer way than that implemented by classic cryptography (based on discrete logarithms and factorization of prime numbers). The most promising way of realizing a QKD network (especially over great distances) in the near future is by a constellation of satellites. This paper considers the problem of optimizing the orbits of the satellites in order to maximize the minimum key length shared in a network of ground stations over a fixed amount of time. Different networks of stations are considered and the influence of their geographical disposition on the design and the performance index is highlighted. The networks considered are: a global constellation, a regional European constellation, and two in which there are groups of stations in two different narrow bands of latitude. The effect of Inter-satellite links is then taken into account and how, in some cases, they can improve the performances. Finally the daily performance of the considered constellations are analyzed.

RIS-assisted physical layer key generation by exploiting randomness from channel coefficients of reflecting elements and OFDM subcarriers

Physical layer key generation is a lightweight technique to establish secret keys securely between resource-constrained devices, but it is ineffective when wireless channels are static or blocked. Physical layer key generation is improved by the use of reconfigurable intelligent surfaces (RISs) to control massive reflecting elements. The channel coefficients of massive reflecting elements serve as a source of randomness for generating secret keys. However, the correlation between the channel coefficients of reflecting elements and OFDM subcarriers causes measurement redundancy, which poses a threat to secret keys. We analyze the secret key rate (SKR) and construct analytical expressions for it. Furthermore, we propose a preprocessing method for decorrelating the measurements, which greatly reduces the computational complexity. Simulation results validate the SKR, bit disagreement ratio (BDR), and randomness. Compared to existing schemes, the proposed scheme greatly improves the SKR.

An Authentication Protocol for the Medical Internet of Things

The progress in biomedical sensors, Internet of Things technologies, big data, cloud computing, and artificial intelligence is leading the development of e-health medical systems, offering a range of new and innovative services. One such service is remote patient monitoring, where medical professionals are able to collect and examine a patient’s medical data remotely. Of course, in these systems, security and privacy are of utmost importance and we need to verify the identities of system users before granting them access to sensitive patient-related data. To this end, several authentication protocols have been recently designed specifically for e-health systems. We survey several of these protocols and report on flaws and shortcomings we discovered. Moreover, we propose an authentication protocol that enables a medical professional and the network of sensors used by a patient to authenticate each other and share a cryptographic key to be used for security in a communication session. The protocol also enables the dynamic assignment of patients to doctors in order to control access to patients’ data. We perform a security analysis of the protocol both formally, using the ProVerif protocol analysis tool, and informally, demonstrating its security features. We show that our protocol achieves mutual authentication, secret key establishment, forward secrecy, and anonymity. In terms of performance, the protocol is computationally lightweight, as it relies on symmetric key cryptography. This is demonstrated by comparing the computational cost of our protocol (in terms of execution time) with that of other similar protocols.

Data Analysis in an Entanglement Network Using Numerical Methods

While the foundation of quantum theory has been debated, its pragmatism has made it enormously productive. Establishing secret keys over long distances has been realized in the real world. Once considered only a hype, quantum computers have also been implemented in laboratories and are performing computations that are superior to their classical counterparts. In this paper, building on previous work, three 2-level entangled states are studied. In particular, the extensive range of states that yield the near-optimal result when entanglement swapping is applied at joints is numerically examined. This result is useful in establishing long-distance maximally entangled states, which are often preferred to short, non-maximal ones when used in applications. The precise nature of physical reality has been debated ever since the birth of quantum theory about a century ago. In this paper, reality is described not only in its physical aspects, but also as it pertains to consciousness. This physical reality in the context of mind is discussed using various examples, including entanglement and the Chinese room argument.

Post-quantum software for distillation of non-orthogonal quantum states through binary frames

Quantum cryptography is a paradigm for the establishment of secret keys and data confidentiality, which represents an alternative in the quantum era because its security properties are based on the principles of quantum physics. Unfortunately, errors that occur during transmission and detection of quantum states have made it difficult to implement this technology globally. However, a new cryptographic key quantum distribution scheme based on non-orthogonal state pairs has recently been published which considerably outperforms known schemes. This article describes the fundamentals of this protocol which are represented as an algorithm and the pseudo-code of the most relevant functions of the system is shown; The current development of the software for the distillation of non-orthogonal quantum states by means of binary frames is presented, which demonstrates the transmission control, reconciliation and privacy amplification of the shared secret bits. Likewise, we present the results obtained from the computer system and its interpretation in relation to the efficiency of the protocol, which exceeds 50% channel error rates and a quadratic growth of the length of the secret key as a function of the number of double detection events. Objectives: Demonstrate the effectiveness of the non-orthogonal state distillation protocol through binary frames using the software developed. Methodology: For the development of this project, the following methodology has been carried out (see Figure 1). Contribution: The results of this software guide tests for quantum distillation in an experimental communications environment in order to provide a useful solution in the era of quantum information transmission and communication technologies.

Horizontal Side-Channel Vulnerabilities of Post-Quantum Key Exchange and Encapsulation Protocols

Key exchange protocols and key encapsulation mechanisms establish secret keys to communicate digital information confidentially over public channels. Lattice-based cryptography variants of these protocols are promising alternatives given their quantum-cryptanalysis resistance and implementation efficiency. Although lattice cryptosystems can be mathematically secure, their implementations have shown side-channel vulnerabilities. But such attacks largely presume collecting multiple measurements under a fixed key, leaving the more dangerous single-trace attacks unexplored. This article demonstrates successful single-trace power side-channel attacks on lattice-based key exchange and encapsulation protocols. Our attack targets both hardware and software implementations of matrix multiplications used in lattice cryptosystems. The crux of our idea is to apply a horizontal attack that makes hypotheses on several intermediate values within a single execution all relating to the same secret, and to combine their correlations for accurately estimating the secret key. We illustrate that the design of protocols combined with the nature of lattice arithmetic enables our attack. Since a straightforward attack suffers from false positives, we demonstrate a novel extend-and-prune procedure to recover the key by following the sequence of intermediate updates during multiplication. We analyzed two protocols, Frodo and FrodoKEM , and reveal that they are vulnerable to our attack. We implement both stand-alone hardware and RISC-V based software realizations and test the effectiveness of the proposed attack by using concrete parameters of these protocols on physical platforms with real measurements. We show that the proposed attack can estimate secret keys from a single power measurement with over 99% success rate.

Statistical inference attack against PHY-layer key extraction and countermeasures

The establishment of secure secret keys ahead of transmissions is one of the key issues in the field of information security. The security of traditional cryptographic secret key establishment mechanisms is seriously challenged by computing-intensive attacks, with the fast growth of high-performance computing. As an alternative, considerable efforts have been made to develop physical (PHY) layer security measures in recent years, such as link-signature-based (LSB) secret key extraction techniques. Those mechanisms have been believed secure, based on the fundamental assumption that wireless signals received at two locations are uncorrelated when separated by more than half a wavelength. However, this assumption does not hold in some circumstances under latest observations, rendering LSB key extraction mechanisms vulnerable to attacks. To address this problem, the formal theoretical analysis on channel correlations in both real indoor and outdoor environments is provided in this paper. Moreover, this paper proposes empirical statistical inference attacks (SIA) against LSB key extraction, whereby an adversary infers the signature of a target link. Consequently, the secret key extracted from that signature has been recovered by observing the surrounding links. In contrast to prior literature that assumes theoretical link-correlation models for the inference, our study does not make any assumption on link correlation. Instead, we employ machine learning (ML) methods for link inference based on empirically measured link signatures. We further propose a countermeasure against the SIAs, called forward-backward cooperative key extraction protocol with helpers (FBCH). In the FBCH, helpers (other trusted wireless nodes) are introduced to provide more randomness in the key extraction. Our experimental results have shown that the proposed inference methods are still quite effective even without making assumptions on link correlation. Furthermore, the effectiveness of the proposed FBCH protocol is validated by our experiment results.

Secret Key Establishment Using Modified Quantization Log For Vehicular Ad-Hoc Network

Traditional cryptographic approaches such as symmetric and asymmetric cryptography are commonly employed to solve network security issues. The Secret Key Generation (SKG) system has the advantage of extracting secret keys from a wireless channel's physical layer information. It allows two wireless devices within the transmission range to extract a shared symmetric key without the use of a fixed key distribution infrastructure, allowing vehicular ad hoc networks to exchange information (VANET). This study aims to create a secure data communication system on the Vehicular Ad-Hoc Network using RSS Key Generation. Starting from the Modified Quantization Log, the results of the Modified Quantization Log show that the average KDRM between Alice and Bob is the average KDRM between Alice and Bob is 9.4%; meanwhile, the average KGR is 71.4 bps. This shows that the number of bit mismatches after the Modified Quantization Log process between the two valid users is already small, because they have used the pre-processing process in front of them, namely using the Kalman Filter and from the results of the BCH Code to be matched again so that it becomes the key. The next process is Universal Hash which is tested with the NIST test. The NIST Test parameters used are approximately entropy, frequency, block frequency, longest run, cumulative sum forward, and cumulative sum reverse. The existing results are appropriate; namely, the threshold in p whose value is above 0.01 is achieved. From the results of the Average Approximate Entropy, it is found that the largest value is obtained by the 40k10ms scheme, which is 0.7352.

Adaptive and Optimum Secret Key Establishment for Secure Vehicular Communications

In intelligent transportation systems (ITS), communications between vehicles, i.e. vehicle-to-vehicle (V2V) communications are of greatest importance to facilitate autonomous driving. The current state-of-the-art for secure data exchange in V2V communications relies on public-key cryptography (PKC) consuming significant computational and energy resources for the encryption/decryption process and large bandwidth for the key distribution. To overcome these limitations, physical-layer security (PLS) has emerged as a lightweight solution by exploiting the physical characteristics of the V2V communication channel to generate symmetric cryptographic keys. Currently, key-generation algorithms are designed via empirical parameter settings, without resulting in optimum key-generation performance. In this paper, we devise a key-generation algorithm for PLS in V2V communications by introducing a novel channel response quantisation method that results in optimum performance via analytical parameter settings. Contrary to the current state-of-the-art, the channel responses incorporate all V2V channel attributes that contribute to temporal variability, such as three dimensional (3D) scattering and scatterers’ mobility. An extra functionality, namely, Perturbe-Observe (PO), is further incorporated that enables the algorithm to adapt to the inherent non-reciprocity of the V2V channel responses at the legitimate entities. Optimum performance is evidenced via maximisation of the key bit generation rate (BGR) and key entropy (H) and minimisation of the key bit mismatch rate (BMR). A new metric is further introduced, the so-called secret-bit generation rate (SBGR), as the ratio of the number of bits which are successfully used to compose keys to the total amount of channel samples. SBGR unifies BGR and BMR and is thus maximised by the proposed algorithmic process.

Feasibility of satellite-to-ground continuous-variable quantum key distribution

Establishing secure communication links at a global scale is a major potential application of quantum information science but also extremely challenging for the underlying technology. Although milestone experiments using satellite-to-ground links and exploiting singe-photon encoding for implementing quantum key distribution have shown recently that this goal is achievable, it is still necessary to further investigate practical solutions compatible with classical optical communication systems. Here, we examine the feasibility of establishing secret keys in a satellite-to-ground downlink configuration using continuous-variable encoding, which can be implemented using standard telecommunication components certified for space environment and able to operate at high symbol rates. Considering a realistic channel model and state-of-the-art technology, and exploiting an orbit subdivision technique for mitigating fluctuations in the transmission efficiency, we find positive secret key rates for a low-Earth-orbit scenario, whereas finite-size effects can be a limiting factor for higher orbits. Our analysis determines regions of values for important experimental parameters where secret key exchange is possible and can be used as a guideline for experimental efforts in this direction.

Wireless-Assisted Key Establishment Leveraging Channel Manipulation

Wireless communication is easily eavesdropped due to the broadcast nature of the wireless medium. This has spurred extensive research into secret key establishment using physical layer characteristics of wireless channels. In all these schemes, the secret keys directly originate from the physical features of the real wireless channel, which is highly dependent on the communication environment nearby. Also, previous schemes require performing information reconciliation, which increases both the costs and the risk of key leakage. In this paper, we exhibit a novel wireless key establishment method allowing the transmitter to specify arbitrary content as the key and cause the receiver to obtain the same key leveraging a channel manipulation technique. We furthermore enable the transmitter to apply error-correction code to the key, so that the receiver can automatically correct any mismatched bits without sending key-related information back to the transmitter over the public channel. Experimental results demonstrate that our key establishment method reaches a success rate as high as 91.0 percent for establishing a 168-bit key between the transmitter and the receiver, and meanwhile the chance that the eavesdropper can infer the key in meter-order range of the receiver is subdued into the range of 0~0.10 percent.

A Lightweight and Robust Secure Key Establishment Protocol for Internet of Medical Things in COVID-19 Patients Care.

Due to the outbreak of COVID-19, the Internet of Medical Things (IoMT) has enabled the doctors to remotely diagnose the patients, control the medical equipment, and monitor the quarantined patients through their digital devices. Security is a major concern in IoMT because the Internet of Things (IoT) nodes exchange sensitive information between virtual medical facilities over the vulnerable wireless medium. Hence, the virtual facilities must be protected from adversarial threats through secure sessions. This article proposes a lightweight and physically secure mutual authentication and secret key establishment protocol that uses physical unclonable functions (PUFs) to enable the network devices to verify the doctor’s legitimacy (user) and sensor node before establishing a session key. PUF also protects the sensor nodes deployed in an unattended and hostile environment from tampering, cloning, and side-channel attacks. The proposed protocol exhibits all the necessary security properties required to protect the IoMT networks, like authentication, confidentiality, integrity, and anonymity. The formal AVISPA and informal security analysis demonstrate its robustness against attacks like impersonation, replay, a man in the middle, etc. The proposed protocol also consumes fewer resources to operate and is safe from physical attacks, making it more suitable for IoT-enabled medical network applications.

Sum Secret Key Rate Maximization for TDD Multi-User Massive MIMO Wireless Networks

Physical-layer key generation (PKG) based on channel reciprocity has recently emerged as a new technique to establish secret keys between devices. Most works focus on pairwise communication scenarios with single or small-scale antennas. However, the fifth generation (5G) wireless communications employ massive multiple-input multiple-output (MIMO) to support multiple users simultaneously, bringing serious overhead of reciprocal channel acquisition. This paper presents a multi-user secret key generation in massive MIMO wireless networks. We provide a beam domain channel model, in which different elements represent the channel gains from different transmit directions to different receive directions. Based on this channel model, we analyze the secret key rate and derive a closed-form expression under independent channel conditions. To maximize the sum secret key rate, we provide the optimal conditions for the Kronecker product of the precoding and receiving matrices and propose an algorithm to generate these matrices with pilot reuse. The proposed optimization design can significantly reduce the pilot overhead of the reciprocal channel state information acquisition. Furthermore, we analyze the security under the channel correlation between user terminals (UTs), and propose a low overhead multi-user secret key generation with non-overlapping beams between UTs. Simulation results demonstrate the near-optimal performance of the proposed precoding and receiving matrices design and the advantages of the non-overlapping beam allocation.

Load Based Key Generation for MANETs: A Comparative Study with DSR and AODV

Automatic key establishment schemes are the root of secure communication in Mobile adhoc networks(MANETs). These schemes are not universal, their performance depends on many factors like routing protocols, type of attackers aimed at, the parameter used for key generation, etc. Among the routing protocols used in MANETs the most popular ones are reactive routing protocols DSR and AODV. In this paper, an efficient secret key establishment technique using traffic matrix is simulated in the two reactive routing protocol scenarios: DSR (Dynamic Source Routing) and AODV (Ad hoc On-demand Distance Vector routing). The simulation results are compared and analyzed in terms of the key generation complexity, packet loss ratio and active attacker detection. Finally the paper concludes the fact that traffic load based key generation scheme is preferable for reactive routing protocol based systems.

IbPaKdE: identity-based pairing free authenticated key and data exchange protocol for wireless sensor networks

This piece of work addresses the challenges, such as less computational complexity, energy efficient, low communication overhead, and low memory overhead for the design of a key distribution approach by combining identity-based cryptography (IBC) with symmetric key cryptography (SKC). The proposed identity-based pairing free authenticated key and data exchange protocol (IbPaKdE) avails advantages of both IBC and SKC. IbPaKdE supports pairing free key distribution i.e., prior communication for secret key establishment is not required. The proposed IbPaKdE uses IBC strategy for secure exchange of keys and SKC to provide security to the data to be transmitted. The on demand establishment of keys eliminates the permanent storage of important credentials in the sensor nodes. Simulation results of the proposed IbPaKdE approach is compared with that of hashed identity-based secure key and data exchange (HISKDE). The results show that the IbPaKdE incur better results compared to HISKDE in terms of the above challenges.

Secure Random Phase Key Exchange Schemes for Image Cryptography

We propose novel random phase key exchange schemes for image cryptography, which are complex sinusoidal waveform versions of the Diffie–Hellman (DH) key exchange algorithm. We demonstrate that the proposed schemes can be particularly helpful to establish a shared secret key in Fourier optics-based image cryptosystems since the problem of symmetric secret key establishment is one of the fundamental difficulties in Fourier optics-based image cryptography. We also propose a ring-type key exchange system in which multiple users can securely share a secret key, which is an extension of the key exchange scheme for two users. The schemes are verified by numerical simulations.

Using mm-Waves for Secret Key Establishment

The fact that millimeter-wave (mmWave) communication needs to be directional is usually perceived as a challenge; in this letter, we argue that it enables efficient secret key sharing that is unconditionally secure from passive eavesdroppers by building on packet erasures. We showcase the potential of our approach in two setups: 5G networks and vehicle platooning. In both cases, with the right choice of parameters, we can potentially establish keys in the order of tenths of Mb/s. These first results are based on some simplifying assumptions, yet we believe that they give incentives to further explore such techniques.

Physical Layer Key Generation in 5G and Beyond Wireless Communications: Challenges and Opportunities

The fifth generation (5G) and beyond wireless communications will transform many exciting applications and trigger massive data connections with private, confidential, and sensitive information. The security of wireless communications is conventionally established by cryptographic schemes and protocols in which the secret key distribution is one of the essential primitives. However, traditional cryptography-based key distribution protocols might be challenged in the 5G and beyond communications because of special features such as device-to-device and heterogeneous communications, and ultra-low latency requirements. Channel reciprocity-based key generation (CRKG) is an emerging physical layer-based technique to establish secret keys between devices. This article reviews CRKG when the 5G and beyond networks employ three candidate technologies: duplex modes, massive multiple-input multiple-output (MIMO) and mmWave communications. We identify the opportunities and challenges for CRKG and provide corresponding solutions. To further demonstrate the feasibility of CRKG in practical communication systems, we overview existing prototypes with different IoT protocols and examine their performance in real-world environments. This article shows the feasibility and promising performances of CRKG with the potential to be commercialized.

On the using of Rényi’s quadratic entropy for physical layer key generation

As a promising way for establishing secret keys, physical layer key generation has been broadly studied, which typically extracts secret keys with wireless channel characteristics. The existing schemes proved that temporal channel variations, channel reciprocity and spatial de-correlation of wireless channel greatly affected the performance of physical layer key generation. In this paper, the application of collision entropy (Rényi’s quadratic entropy) for improving physical layer key generation is discussed. Specifically, after collecting sufficient channel measurements, a channel measurement evaluation mechanism based on collision entropy is implemented to determine the adequacy of these measurements. Consequently, some consecutive measurements with smaller collision entropies are dropped and the reserved measurements are applied as input of the following process. Based on the evaluation mechanism, an adaptive and efficient key generation scheme is proposed. The proposed scheme consists of five components: channel probing, the evaluation mechanism, the adaptive quantization, information reconciliation and privacy amplification. To validate this scheme, several experiments in real environments are conducted. Different from the existing schemes, the received signal strength (RSS) measurements derived by heterogeneous devices are used as channel measurements. The results show that: (1) compared with homogeneous devices, RSS sequences of heterogeneous devices have more discrepancies and these discrepancies make key generation more challenging; (2) the proposed evaluation mechanism can effectively reduce bit mismatch rate and enhance the efficiency of information reconciliation; (3) compared with other schemes, the proposed key generation scheme can efficiently generate shared secret keys between heterogeneous transceivers in real environments.