Secure Key Distribution Scheme Research Articles

Experimental demonstration of 17.5 Gb/s physical layer key distribution over 100 km fiber link based on channel physical intrinsic property and polarization reciprocity.

Secure key distribution (SKD) schemes based on fiber channel reciprocity provide information-theoretic security as well as a simple symmetric structure. However, the nonlinear effects and backscattering effects introduced during the bidirectional transmission process degrade the channel reciprocity. Recent unidirectional SKD schemes avoid non-reciprocal factors but require additional negotiation mechanisms to aggregate the transmitter and receiver data. Here, we propose a unidirectional SKD scheme based on channel physical intrinsic property and polarization reciprocity. The designed loopback structure constructs asymmetry between legitimate and illegitimate parties while aggregating data. The deployment of a broadband chaotic entropy source significantly improves the key generation rate (KGR). In the experiment, the KGR reaches 17.5 Gb/s, and the distribution distance reaches 100 km.

Secure key generation and distribution scheme based on historical fiber channel state information with LSTM.

In this paper, a scheme to realize unclonable physical-layer security key generation and distribution (PL-SKGD) based on historical fiber channel state information (HFCSI) is proposed. PL-SKGD schemes based on channel characteristics for enhancing the physical-layer security of optical networks have been proposed in recent years. However, there are potential disadvantages in these schemes, such as 1) low key generation rate (KGR): the slow frequency of the analog waveform change of the channel characteristic leading to low KGR; 2) incompatibility with existing infrastructure: active scrambling to increase the frequency of channel characteristic changes, or tracking changes of channel characteristics requires additional devices; 3)easy to be cloned: all of the optical channel state information is reflected in the signal transmitted inside the fiber, which makes it easy to reproduce by illegal eavesdropper through features analysis and other methods. In order to solve the above problems, a PL-SKGD scheme is designed which uses the chain structure composed of long short-term memory neural network (LSTM-NN) units to learn and store the unique mapping relationship between historical channel time series and provides unclonability based on the fundamental fact that the eavesdropper Eve can never obtain the full HFCSI. The simulation conducted in a quadrature phase shift keying point-to-point optical link system verified successfully that KGR = 0.82 Gbit/s error-free SKGD. The loss function of LSTM-NN drops sharply in the early stages of training and remains a small value. The security of the SKGD system is analyzed, which effectively improves the unclonability of the system. Finally, it is verified that the optimal fiber channel length for error-free SKGD of the proposed scheme is 150 km considering the error correction capability of information reconciliation and weighing key sequence error rate and valid bit generation rate.

Synchronization of complexity enhanced chaos in semiconductor lasers

In synchronized chaotic lasers based secure key distribution and other encrypted communications, presence of the time delay signature in chaos poses a threat to security. So the transmitter and receiver lasers should preferably be operated in complexity enhanced chaotic regime where the time delay signature is hidden. However, achieving good synchronization in experiments in such regime is challenging. We report experimental demonstration of achieving excellent synchronization between two semiconductor lasers even when both the lasers are operating in complexity enhanced chaotic regime with absolutely no time delay signature present in their output. This chaotic regime is ensured by evaluating the auto correlation function, permutation entropy and spectrum analysis of the time series. As a measure of synchronization, cross-correlation coefficient of 0.923 is achieved between the transmitter and receiver lasers. This results are of immense importance in chaos based secure key distribution and other encrypted communication schemes.

Dynamic Secure Key Distribution Based on Dispersion Equalization and Cellular Automata for Optical Transmission

This paper proposes a dynamic secure key distribution scheme based on dispersion equalization and cellular automata (CAs). The scheme effectively eliminates the key inconsistency problem caused by imperfect channel reciprocity, and dynamic key sequences can be conveniently generated with large key space in long-haul optical transmission. In the process of communication, the legitimate parties obtain the secure core parameter from the frequency domain equalizer algorithm, and a final key sequence is generated through CA iterations on the basis of the core parameter. The randomness and reciprocity characteristics of the channel ensure the security and uniqueness of the core parameter and final key sequence. With 10G Baud 16 quadrature amplitude modulation over 400 km standard single-mode fiber transmission, the proposed scheme is verified with a free key error rate and an unlimited key generation rate. The security robustness of this scheme was theoretically analyzed and verified by sweeping the eavesdropper’s tapping position and improving CA operation processing. The proposed key distribution scheme is compatible with the existing transmission system for different signal modulation formats.

Secure key distribution based on the polarization reciprocity of fiber and a coherent reception architecture.

Secure key distribution (SKD) schemes based on the interaction between a broadband chaotic source and the reciprocity of a fiber channel exhibit reliable security and a high key generation rate (KGR). However, under the intensity modulation and direct detection (IM/DD) architecture, these SKD schemes cannot achieve a long distribution distance due to the limitations on the signal-to-noise ratio (SNR) and the receiver's sensitivity. Here, based on the advantage of the high sensitivity of coherent reception, we design a coherent-SKD structure where orthogonal polarization states are locally modulated by a broadband chaotic signal and the single-frequency local oscillator (LO) light is transmitted bidirectionally in the optical fiber. The proposed structure not only utilizes the polarization reciprocity of optical fiber but also largely eliminates the non-reciprocity factor, which can effectively extend the distribution distance. The experiment realized an error-free SKD with a transmission distance of 50 km and a KGR of 1.85 Gbit/s.

10 Gb/s physical-layer key distribution in fiber using amplified spontaneous emission.

High-speed physical-layer secure key generation and distribution (SKGD) schemes via channel reciprocity are achieved using external electro-optical modulation or random source distribution via additional fiber links. Here, we propose and demonstrate an SKGD scheme using the fluctuation of polarization states from an amplified spontaneous emission (ASE) source, without any external electro-optical modulation or additional fiber link. Experimentally, an error-free key generation rate (KGR) of 10.1 Gb/s is achieved over a 10-km standard single-mode fiber (SSMF), with true randomness originating from ASE. Moreover, the single fiber channel can be shared for SKGD as well as data transmission, allowing the integration of the proposed SKGD with the deployed fiber infrastructure.

Stable secure key distribution scheme via orthogonal polarizations and a joint source-channel model.

Optical secure key distribution (SKD) based on reciprocity has been the subject of increasing discussion, for its inherent information-theoretic safety and because there is less occupation of fiber channels. The combination of reciprocal polarization and broadband entropy sources has proven effective in increasing the rate of SKD. However, the stabilization of such systems suffers from the limited span of polarization states and inconsistent polarization detection. The specific causes are analyzed in principle. To solve this issue, we propose a strategy for extracting secure keys from orthogonal polarizations. Optical carriers with orthogonal polarizations at interactive parties are modulated by external random signals using polarization division multiplexing dual-parallel Mach-Zehnder modulators. After bidirectional transmission through a 10-km fiber channel, error-free SKD with a rate of 2.07 Gbit/s is experimentally realized. The high correlation coefficient of the extracted analog vectors can be maintained for over 30 min. The proposed method is a step toward the development of secure communication with high speed and feasibility.

Secure key distribution based on hybrid chaos synchronization between semiconductor lasers subject to dual injections.

We propose and numerically demonstrate a novel secure key distribution (SKD) scheme by using dynamically synchronized semiconductor lasers (SLs) subject to common dual injections from two mutually coupled SLs. The performance of hybrid chaos synchronization, complexity of chaotic signals, chaos-based key distribution, and the privacy of SKD scheme are systematically discussed. It is shown that high-quality hybrid chaos synchronization of zero lag and lead lag can be both achieved between two local lasers under different injection delay conditions, whereas low cross correlations are observed among the driving lasers and the local lasers. By randomly perturbing the injection delays with four independent random sequences, the outputs of local SLs can be dynamically synchronized. Extracting the outputs in the synchronization time slots of zero lag and lead lag, synchronous entropy sources are obtained and used to generate keys with high consistency at local ends of Alice and Bob, which are robust to the parameter mismatches of local lasers to some extent. Moreover, large BER is calculated in two types of typical illegal attacks, which demonstrates the security of the proposed scheme. This work proposed a high-level secure key distribution solution to one-time pad communication.

Physical secure key distribution based on chaotic self-carrier phase modulation and time-delayed shift keying of synchronized optical chaos.

High speed physical secure key distribution in a classical optical fiber channel is unprecedentedly desired for modern secure communication, but it still remains a worldwide technical challenge. In this paper, we propose and experimentally demonstrate a novel high-speed physical secure key distribution scheme based on chaotic optical signal processing and private hardware modules, which employs chaotic self-carrier phase modulation for chaotic bandwidth expansion and time-delayed shift keying of commonly driven synchronized optical chaos for physical layer security. In this scheme, the entropy source rate of synchronized chaos output from two remote response lasers is greatly expanded by chaotic self-carrier delayed nonlinear phase disturbance, which facilitates high speed key extraction from the entropy source with guaranteed randomness. Moreover, a synchronization recovery time of sub-nanosecond is achieved by dynamic keying of the chaotic delay time after chaos synchronization to accelerate the key distribution rate. Based on the proposed scheme, a high physical key distribution rate of 2.1 Gb/s over 40 km is successfully demonstrated in the experiment. The proposed solution provides a promising strategy for future high-speed key distribution based on chaotic optical signal processing and classical fiber channel.

Gbit/s secure key generation and distribution based on the phase noise of an amplified spontaneous emission source.

In this paper, a secure key generation and distribution scheme based on the phase noise of an amplified spontaneous emission source is proposed and experimentally verified. A giant key generator that contains two distribution arms is used to generate a specific beat dependent on the path length difference of the arms. Through the method of balanced subtraction of the local signals, the effect of the intensity noise has been mainly excluded, and the two legal users obtain the consistent differential signal that depended on the phase noise. Experiment results show that the correlation coefficient of the key signals reaches to about 0.89, and the bit generation rate of the scheme achieves to 3.06 Gbit/s under a length of 20 km standard single-mode optical fiber route, as the bit error rate stays under 0.02%. Moreover, the converted digital key stream has passed the NIST statistical test suite, which means that the scheme is inherently random in the statistical sense. With the excellent performance mentioned above, the proposed scheme provides a simple and efficient solution for the method of one-time pad.

Perspective—On the thermodynamics of perfect unconditional security

A secure key distribution (exchange) scheme is unconditionally secure if it is unbreakable against arbitrary technological improvements of computing power and/or any development of new algorithms. There are only two families of experimentally realized and tested unconditionally secure key distribution technologies: quantum key distribution (QKD), the base of quantum cryptography, which utilizes quantum physical photonic features, and the Kirchhoff-Law–Johnson-Noise (KLJN) system that is based on classical statistical physics (fluctuation–dissipation theorem). The focus topic of this paper is the thermodynamical situation of the KLJN system. In all the original works, the proposed KLJN schemes required thermal equilibrium between the devices of the communicating parties to achieve perfect security. However, Vadai et al., in (Nature) Sci. Rep. 5, 13653 (2015) show a modified scheme, where there is a non-zero thermal noise energy flow between the parties, yet the system seems to resist all the known attack types. We introduce an attack type against their system. The attack utilizes coincidence events between the line current and voltages. We show that there is a non-zero information leak toward the Eavesdropper, even under idealized conditions. As soon as the thermal equilibrium is restored, the system becomes perfectly secure again. In conclusion, perfect unconditional security requires thermal equilibrium.

Point to multi-point physical-layer key generation and distribution in passive optical networks.

A point to multi-point physical-layer secure key generation and distribution (SKGD) scheme is proposed and demonstrated in passive optical networks (PONs), where the optical line terminal (OLT) broadcasts optical lights with fast fluctuating states of polarization (SOPs) to the optical network units (ONUs). The highly correlated key waveforms are shared between OLT and ONUs, and the high-level security of the SKGD scheme is guaranteed by the high sensitivity of SOP dynamics associated with the specific fiber links. As a proof of concept, a 3.9 Gb/s SKGD is achieved over 11 km single-mode fiber, where a Sagnac interferometer-based polarization scrambler is constructed as the high-speed random source. Moreover, the generated key sequences are verified to be error free and truly random. The proposed SKGD scheme offers a flexible solution for security enhancement in PONs, and is also compatible with the current PON infrastructure.

Enhanced BB84 quantum cryptography protocol for secure communication in wireless body sensor networks for medical applications.

Wireless body sensor network (WBSN) is an interdisciplinary field that could permit continuous health monitoring with constant clinical records updates through the Internet. WBAN is a special category of wireless networks. Coronavirus disease 2019 (COVID-19) pandemic creates the situation to monitor the patient remotely following the social distance. WBSN provides the way to effectively monitor the patient remotely with social distance. The data transmitted in WBSN are vulnerable to attacks and this is necessary to take security procedure like cryptographic protocol to protect the user data from attackers. Several physiological sensors are implanted in the human body that will collect various physiological updates to monitor the patient’s healthcare data remotely. The sensed information will be transmitted wirelessly to doctors all over the world. But it has too many security threats like data loss, masquerade attacks, secret key distribution problems, unauthorized access, and data confidentiality loss. When any attackers are attacking the physiological sensor data, there is a possibility of losing the patient’s information. The creation, cancellation, and clinical data adjustment will produce a mass effect on the healthcare monitoring system. Present-day cryptographic calculations are highly resistant to attacks, but the only weak point is the insecure movement of keys. In this paper, we look into critical security threats: secure key distribution. While sharing the secret key between communicating parties in the wireless body sensor networks in the conventional method like via phone or email, the attackers will catch the private key. They can decrypt and modify more sensitive medical data. It can cause a significant effect like death also. So need an effective, secure key distribution scheme for transmission of human body health related data to medical professional through wireless links. Moreover, a new enhanced BB84 Quantum cryptography protocol is proposed in this paper for sharing the secret key among communicating parties in a secure manner using quantum theory. Besides, a bitwise operator is combined with quantum concepts to secure the patient’s sensed information in the wireless environment. Instead of mail and phone via sharing secret key, quantum theory with the bitwise operator is used here. Therefore, it is not possible to hack the secret key of communication. The body sensor’s constrained assets as far as battery life, memory, and computational limit are considered for showing the efficiency of the proposed security framework. Based on experimental results, it is proven that the proposed algorithm EBB84QCP provides high secure key distribution method without direct sharing the secret key and it used the quantum mechanism and bitwise operator for generating and distributing secret key value to communicating parties for sensitive information sharing in the wireless body sensor networks.

Lightweight Secure Authentication and Key Distribution Scheme for Vehicular Cloud Computing

A vehicular ad-hoc network (VANET) is the basic block in building an intelligent transportation system that improves the traffic flow and makes needed information conveniently accessible. VANET depends on a dense exchange of sensed data between vehicles and Road Side Units (RSUs). A large amount of sensed data requires a huge computation and storage capabilities, which is provided by the vehicular cloud computing (VCC). However, the security problems of data confidentiality, access control, vehicles’ authentication, and conductors’ privacy in VCC are issues that need to be solved. In this paper, we propose an efficient algorithm to ensure VCC security and privacy. We use Pseudo-ID instead of vehicles’ real ID to provide conductors’ privacy, Identifier-Based Signature mechanism is used to guarantee vehicles’ authentication, and Ciphertext-Policy Attribute-Based Encryption (CP-ABE) algorithm is used for key distribution. Our liGhtweight secURe AutheNticaTion and keY distribution scheme for vehicular cloud computing (GUARANTY) ensures a secure keys distribution to minimize the encryption and decryption computation cost. Vehicles use a symmetrical cryptography in their communication. We analyze the security of our algorithm using AVISPA tool. We use this tool to simulate insiders and outsiders attacks. We evaluate our algorithm’s performance in terms of computation delay and reception rate.

2.7 Gb/s Secure Key Generation and Distribution Using Bidirectional Polarization Scrambler in Fiber

A physical-layer secure key generation and distribution (SKGD) scheme in classical fiber channel is proposed and demonstrated using a bidirectional wide-band polarization scrambler (WBPS), to alter rapidly and symmetrically the state of polarization (SOP) for the two counter-propagating optical signals in fiber. Due to the optical channel reciprocity, highly-consistent key bits can be extracted from the correlated SOP fluctuations, while the key secrecy is ensured by the fiber channel uniqueness. A final key generation rate (KGR) of 2.7 Gb/s is demonstrated over 10 km single mode fiber (SMF), where error-free and true randomness of the generated key are achieved after post-processing. The obtained KGR at Gb/s makes a further step towards the implementation of one-time-pad data encryption with perfect secrecy in fiber networks.

Secure key generation and distribution scheme based on two independent local polarization scramblers.

We propose a practical secure key generation and distribution (SKGD) scheme for actual application. Based on the experiment results of the polarization properties of the actual optical-fiber link, we propose a SKGD method by the active modulation of the state of polarization of the optical-fiber by two polarization scramblers placed at the local end of the legal users in the point-to-point communication system. Experiment results prove that the signals received by legal users share high correlation using 20 km standard single-mode fiber and 1 KHz polarization scrambling rate, and the bit generation rate can reach to 1216 bit/s with a bit error rate of ∼0.33%. Security of the system is also analyzed in terms of the polarization properties of the system; the theoretical and experimental results indicate that the proposed scheme possesses high security due to the invisibility of the key signal and the technical difficulty of the recovery of the key sequence.

High-Rate Secure Key Distribution Based on Private Chaos Synchronization and Alternating Step Algorithms

We propose and numerically demonstrate a high-rate secure key distribution scheme based on private chaos synchronization of two semiconductor lasers subject to common driving injection and an alternating step algorithm (ASA). By exchanging the random control parameters that correspond to different feedback delays of local external-cavity semiconductor lasers, the legitimate users Alice and Bob can identify the time slots in which high-quality private chaos synchronization is achieved. Based on this property, a true random seed key can be independently and privately generated by Alice and Bob, in virtue of symmetric post-processing. Moreover, an ASA is designed to generate a new high-rate key as the final key. By the ASA iterations, random final key distribution with an extended rate significantly higher than that of the seed key can be achieved. The feasibility and performance of the proposed high-rate secure key distribution scheme are verified by numerical simulations. This work provides a high-level security and high-rate random key distribution scheme that has the potential to implement one-time-pad encryption in high-speed secure optical communications.

SSKM: Scalable and Secure Key Management Scheme for Group Signature Based Authentication and CRL in VANET

The security in vehicular ad hoc networks (VANETs) has become a large consideration in safeguarding growing applications and intelligent transport systems. A group signature, a popular authentication approach for VANETs, can be implemented to protect vehicular communications against malicious users. However, the issue of securely distributing group keys to fast-moving vehicular nodes arises. The growing size of the certificate revocation list (CRL) has provided the corresponding complication in its management and distribution in VANETs. In this paper, an efficient key management protocol for group signature based authentication is proposed. A group is extended to a domain with various roadside units forming a hierarchical topology. Our proposed scheme provides a secure method to deliver group keys to vehicular nodes, ensuring the security requirements. Similarly, through utilizing the two Bloom filters in our hierarchical topology, an efficient and scalable vehicle revocation mechanism can be achieved that can minimize the CRL size. Our experiment results demonstrate a scalable, efficient, and secure key distribution scheme in vehicular networking. Moreover, an effective CRL management mechanism can be accomplished using the hierarchical topology.

Error-free secure key generation and distribution using dynamic Stokes parameters.

This paper proposes and experimentally demonstrates an error-free secure key generation and distribution (SKGD) scheme in classical optical fiber link by exploiting Stokes parameters (SPs) of the state of polarization (SOP). Due to the unique birefringence distribution of the optical fiber channel, random but high-correlated SPs are shared between Alice and Bob. The dynamic SPs are also affected by the time-varying environmental factors, providing the source of randomness for the secret key extraction. As a proof of concept, key generation rate (KGR) of 213-bits/s is successfully demonstrated over 25-km standard single-mode fiber (SSMF). The error-free SKGD is realized in fiber channel using the information reconciliation (IR) technology, where Bose-Chaudhuri-Hocquenghem (BCH) codes are applied. Due to the channel uniqueness and the high-sensitivity to the initial SOP of optical signals, high-level security is provided by the proposed scheme, which is analyzed and verified against the possible fiber-tapping attacks. Moreover, the proposed SKGD scheme offers additional benefits such as simple structure, low cost, and suitablity for long-haul transmission.

Semiconductor-laser-based hybrid chaos source and its application in secure key distribution.

An analog-digital hybrid optical chaos source and a corresponding secure key distribution (SKD) scheme are proposed. An analog-digital hybrid electro-optic feedback loop is introduced to enhance the robustness of the chaotic semiconductor lasers. The source, which can adopt robust digital synchronization strategies, could generate a broadband analog optical chaotic signal of high dynamical complexity. Furthermore, the source reduces the requirement on the processing speed of digital components and simplifies the hybrid system structure markedly. For demonstrating, we build a SKD system with the proposed chaos source. Since this SKD scheme is compatible with digital optical networks, the commercially available communication techniques can help to make it insensitive to impairments in fiber optic links. This feature has potential in long-haul SKD.