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BB84-state is the non-orthogonal single-photon state which has the advantage of easy implementation compared with the quantum multi-photon entanglement states. In this paper, based on BB84-state, by introducing a trusted third-party voting center, a quantum voting scheme is proposed. In this scheme, by performing corresponding unitary operation on BB84-state, all voters send their voting information to the tallyman Charlie, then Charlie counts all votes under the supervision of voting management center Bob, which ensures that the protocol can resist inside attacks. Moreover, by utilizing the decoy particles, our scheme can efficiently prevent outside attacks. Compared with other related quantum voting protocols, our protocol has higher qubit efficiency and fewer interactive times.

How to solve the information leakage problem has become the research focus of quantum dialogue. In this paper, in order to overcome the information leakage problem in quantum dialogue, a novel approach for sharing the initial quantum state privately between communicators, i.e., quantum encryption sharing, is proposed by utilizing the idea of quantum encryption. The proposed protocol uses EPR pairs as the private quantum key to encrypt and decrypt the traveling photons, which can be repeatedly used after rotation. Due to quantum encryption sharing, the public announcement on the state of the initial quantum state is omitted, thus the information leakage problem is overcome. The information-theoretical efficiency of the proposed protocol is nearly 100%, much higher than previous information leakage resistant quantum dialogue protocols. Moreover, the proposed protocol only needs single-photon measurements and nearly uses single photons as quantum resource so that it is convenient to implement in practice., 6 pages, 1 table

In a secure communication, a one-time session key is needed to be shared among all participants. Most well-known key distribution schemes, such as Diffie–Hellman public-key key distribution scheme invented in 1976 and quantum key distribution scheme invented in 1984 (also called the BB84 scheme), can only allow two users to share a key in conventional one-to-one communications. There are many research papers in the literature to propose group key distribution schemes for multiple participants in modern group communications. In this study, the authors propose lightweight group key distributions using pre-shared pairwise keys. The authors first propose a three-party group key distribution scheme. They then extend the basic three-party scheme to establish a group key for a large size of group communications. The proposed generalised schemes can be based to any type of pairwise key distribution schemes, e.g. either quantum or non-quantum. Moreover, both generalised multi-party group key distribution schemes are lightweight. The main operations in the proposed schemes are key comparison between two or more than two keys (i.e. logic XOR operation) and the computation of key derivation functions.

Security certification of quantum key distribution systems with a practical device is essential for their social deployment. Considering the transmitter, we investigate quantum state generation affected by degraded electrical signals from practical bandwidth-limited devices on high-speed phase-encoding BB84 quantum key distribution systems. The state preparation flaw caused by this degradation undesirably enhances the distinguishability between the two bases for the BB84 protocol and decreases the key generation rate. We propose the state preparation with a dual parallel modulator for increasing the robustness to signal degradation. To verify the effectiveness of the dual parallel modulator, we characterize the generated states using state tomography and estimate the key generation rate based on the Gottesman-Lo-Liitkenhaus-Preskill theory with fidelity derived from the estimated density matrices. Simulation results show that the key generation rate remains unaffected by modulation voltage shifts up to 20%. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Quantum Cryptography uses the counter-intuitive properties of Quantum Mechanics for performing cryptographic tasks in a secure and reliable way. The Quantum Key Distribution (QKD) protocol BB84 has been proven secure against several important types of attacks: collective attacks and joint attacks. Here we analyze the security of a modified BB84 protocol, for which information is sent only in the z basis while testing is done in both the z and the x bases, against collective attacks. The proof follows the framework of a previous paper (Boyer, Gelles, and Mor, 2009), but it avoids a classical information-theoretical analysis and proves a fully composable security. We show that this modified BB84 protocol is as secure against collective attacks as the original BB84 protocol, and that it requires more bits for testing., Comment: 24 pages; 1 figure; this is an improved version of arXiv:1704.01388 [quant-ph], extended to make the security proof (against collective attacks) fully composable

A typical implementation of BB84 protocol for quantum communication uses four laser diodes for transmitting weak coherent pulses, which may not have the same characteristics. We have characterized these lasers for mismatch in various parameters such as spectral width, pulse width, spatial mode, peak wavelength, polarization and their arrival times at the receiver. This information is utilized to calculate possible information leakage through side channel attacks by evaluating mutual information between source and eavesdropper. Based on our experimental observations of cross correlation between parameter values for different laser diodes, we suggest methods to reduce information leakage to Eve.

Time synchronization is crucial for quantum key distribution (QKD) systems. In order to compensate for the time drift caused by the Doppler effect and adapt to the unstable optical link in satellite-to-ground QKD, previous demonstrations generally adopted synchronization methods requiring additional hardware. In this paper, we present a novel synchronization method based on the detected quantum photons, thus simplifying additional hardware and reducing the complexity and cost. This method adopts target frequency scanning to realize fast frequency recovery, utilizes polynomial fitting to compensate for the Doppler effect, and takes use of the vacuum state in the decoy-state BB84 protocol to recover the time offset. This method can avoid the influence of synchronization light jitter, thus improving the synchronization precision and the secure keys as well. Successful satellite-to-ground QKD based on this new synchronization scheme has been conducted to demonstrate its feasibility and performance. The presented scheme provides an effective synchronization solution for quantum communication applications.

A source of bright and pure single photons is an essential tool for photonic quantum technologies, predicted to enable secure communication and networking. Self-assembled quantum dots are among the leading candidates to realise such a source. The currently highest-performing quantum dots emit at wavelengths unsuitable for fibre transmission, with telecom quantum dots lagging in performance. An intermediate step is to use quantum frequency conversion. Here we report to our knowledge the brightest quantum dot based source of telecom photons by frequency converting a near-infrared quantum dot embedded in a micropillar cavity to the telecom C-band. In a single-photon BB84 protocol, this source is capable of producing asymptotic keys rates of 1 kbps at over 150 km of optical fibre.

The transmission security between ground station and satellite is challenging. Some existing multistep algorithms leave lots of loopholes for eavesdropping and attacking in satellite-to-ground communication. For high security, optical communication is a promising solution. In this paper, we propose a control code multiple encryption algorithm (CCMEA) for the single-photon-transmission between satellite and ground station. CCMEA can utilize the control code to respectively encrypt three cognitive optimization sections: loop iteration, polarization coding and order rearrangement, and simulation shows that CCMEA can realize one step transmission to decrease loopholes compared with multistep encryption algorithm. In addition, we design a security detection method by combining the decoy photon analysis and the quantum bit error rate (QBER) analysis. The numerical results show that CCMEA can reduce the security threshold by 27% compared with multistep encryption algorithm of BB84 scheme. Finally, for satellite-to-ground communication, we construct an analytic QBER model on CCMEA with four factors: quantum channel transmission rate, single-photon acquisition probability, measurement factor and data filtering factor. The result demonstrates the effectiveness of CCMEA on satellite-to-ground communication.

Quantum cryptography, the principles of which are based on classical mechanics laws, solves exceptionally the issue of key distribution in classical cryptography. BB84, the first quantum key distribution created by Charles Bennett and Gilles Brassard in 1984 offers unconditional security and allows the transmission of a key with the length equal to the length of the message. According to Vernom, using the key with the above feature once together with an encryption algorithm leads to the formation of a most secure cryptographic system. The paper presents a method for improving the BB84 quantum protocol, using ten states of polarization, quantum memory and direct communication in both directions. The implementation of both the proposed method and the BB84 protocol was done through a C# application.

Quantum key distribution (QKD), ensuring the unconditional security of information, attracts a significant deal of interest. An important task is to design QKD systems as a platform for education as well as for research and development applications and fast prototyping new QKD protocols. Here we present a modular QKD setup driven by National Instruments (NI) cards with open source LabView code, open source Python code for post-processing procedures, and open source protocol for external applications. An important feature of the developed apparatus is its flexibility offering possibilities to modify optical schemes and verify novel QKD protocols. Another distinctive feature of the developed setup is the implementation of the decoy-state protocol, which is a standard tool for secure long-distance quantum communications. By testing the plug-and-play scheme realizing BB84 and decoy-state BB84 QKD protocols, we demonstrate that developed QKD setup shows a high degree of robustness beyond laboratory conditions. We demonstrate the results of the use of the developed modular setup for urban QKD experiments., Comment: 6 pages, 3 figures; published version

In this paper, we study the Big Data security based on quantum information theory. In fact, we discuss the opportunities offered by quantum Key distribution (QKD) protocols and quantum algorithms to increase the security level of Big data. In this respect, we used the BB84 protocol to transfer the sent qubits via a quantum channel and Grover’s algorithm to search in NoSql databases in quantum environment. In order to analyze the effectiveness of quantum information theory on big data, we compare the obtained results with those of classical approaches

We present a versatile transmitter capable of performing both discrete variable and continuous variable quantum key distribution protocols (DV-QKD and CV-QKD, respectively). Using this transmitter, we implement a time-bin encoded BB84 DV-QKD protocol over a physical quantum channel of 47 km and a GG02 CV-QKD protocol with true local oscillator over a 10.5 km channel, achieving secret key rates of 4.1 kbps and 1 Mbps for DV- and CV-QKD, respectively. The reported transmitter scheme is particularly suitable for re-configurable optical networks where the QKD protocol is selected to optimize the performance according to the parameters of the links.

In recent years, the feasibility of quantum key distribution (QKD) in a water channel has been verified by theory and experiment. Here, we present an experimental investigation of QKD and decoy-state QKD based on the BB84 protocol. The experiment was carried out in a 10 m water tank. The attenuation coefficient of tap water is 0.08/m, which is close to Jerlov Type II seawater. We measured the probability-of-detection matrix of polarization states, and the average fidelity of the four polarization states is up to 98.39%. For the 10 m underwater QKD experiment, 20 MHz optical pulses are generated by modulating the laser diode (LD) and attenuated to an average of 0.1 photons per pulse. The security key rate can reach 563.41 kbits/s and the quantum bit error rate (QBER) is 0.36%. Two decoy states (one of which is the vacuum state) was used in the 10 m underwater decoy-state QKD experiment, and the average QBER of signal state is 0.95%, the security key rate reaches 711.29 kbits/s. According to the parameters of the decoy-state experiment, the maximum secure transmission distance of the underwater decoy-state QKD is predicted to be 19.2 m, while it can be increased to 237.1 m in Jerlov Type I seawater with a lower dark count single photon detector (SPD).

Based on the security problems emerged in development process of quantum key distribution, it is introduced that the working principles and basic process of three classical protocols including BB84 protocol, decoy-state protocol, measurement-device-independent protocol, and two new protocols including twin-field protocol, phase-matching protocol as the main line. We deduce the relationship between the key generation rate and channel transmission efficiency of each protocol, and simulate security transmission performance of the above-mentioned protocol. Finally, the characteristics of each protocol are compared analyzed. Relevant research results show that the security transmission performance of phase-matching protocol is better than the others.

The quantum key distribution (QKD) protocol provides an absolutely secure way to distribute secret keys, where security can be guaranteed by quantum mechanics. To raise the key generation rate of classical BB84 QKD protocol, Hwang et al. (Phys Lett A 244(6):489–494, 1998) proposed a subtle variation (Hwang protocol), in which a pre-shared secret string is used to generate the consistent basis. Although the security of Hwang protocol has been verified in ideal condition, its practicality is still being studied in more depth. In this work, we propose a simple attack strategy to obtain all preparation basis by stealing partial information in each round. To eliminate this security threat, we further propose an improved QKD protocol using the idea of iteratively updating the basis. Furthermore, we apply our improved method to decoy-state QKD protocol and double its key generation rate.

The Web clients are consistently expanding step by step. After the starting of the 4G or IMT—Advanced administrations, correspondence over Web expanded definitely. Individuals over every one of the networks like social, monetary, business, money related, and so forth are doing correspondence or trading their esteemed reports over Web. The interest for verifying the information in productive manner has been expanded. As cryptography is the most ideal approach to verify the correspondence. In FRQI, the compression ratio of quantum images is more efficient and achieves quadratic speed in quantum images. Here, BB84 protocol convention is used to execute QKD. It manages the harmonization states that want to transmit the media transmission information with elevated level of security utilizing a glass or optical fiber.

The cryptographic system ensures authentication between the communicating parties through keys, and it cannot be sent over insecure communication channel due to eavesdropping adversary. Distribution approaches are required to support either private or public key cryptosystem that allows key sharing secretly. We represent the existing classical key distribution protocols and relevant quantum methods that overcome the challenges in classical protocols. The keys must be shared at the end of distribution process, and continuum to this, we have quantum key distribution that uses quantum principles which guarantee that key cannot be intercepted. The objective of this paper is to explore quantum key distribution protocols like BB84 and Eckert’s protocol in detail and then to analyze them with classical approaches in comparative parameters and lastly concludes the quantum protocol to be highly secure, advantageous and superior to classical existing protocols.

Quantum key distribution (QKD) allows two parties to establish a shared secret key that is secure against adversaries with unlimited computational power. One such protocol named B92 is quite appealing due to its simplicity but is highly sensitive to channel noise. In this work, we investigate a high-dimensional variant of an extended version of the B92 protocol and show that it can distill a key over high noise channels. The protocol we consider requires that Alice sends only three high-dimensional states and Bob only performs partial measurements. We perform an information-theoretic security analysis of our protocol and compare its key rate to that of a high-dimensional BB84 protocol over depolarization and amplitude damping channels.

In this work, we propose a new protocol for data transmission, using both the potential of quantum encryption expressed by the BB84 protocol and the possibilities offered by distributed ledgers and...

In this article we present the BB84 quantum key distribution scheme from two perspectives. First, we provide a theoretical discussion of the steps Alice and Bob take to reach a shared secret using this protocol, while an eavesdropper Eve is either involved or not. Then, we offer and discuss two distinct implementations that simulate BB84 using IBM’s Qiskit framework, the first being an exercise solved during the “IBM Quantum Challenge” event in early May 2020, while the other was developed independently to showcase the intercept-resend attack strategy in detail. We note the latter’s scalability and increased output verbosity, which allow for a statistical analysis to determine the probability of detecting the act of eavesdropping.

We demonstrate that adaptive optics (AO) can be used to improve tolerance to atmospheric turbulence in free-space optical (FSO) quantum communications. Both the overall secret-key rate and quantum bit-error rate for BB84 protocol have been significantly improved by the AO.

Quantum key distribution (QKD) provides a means of secure communication between two parties. QKD exploits the principle that you cannot eavesdrop on a quantum communication channel without producing a detectable disturbance.

Silica-based planar lightwave circuit (PLC) devices can offer great potential for quantum key distribution (QKD) with the benefits of low-loss, low-cost, large-scale integration, miniaturization, stability and mass production. A quantum decoding integrated chip for QKD based on silica PLC technology was demonstrated, which consists of a variable optical splitter (VOS), an asymmetric Mach–Zehnder interferometer (AMZI) with a thermo-optic phase modulator (TOPM) and a delay line (DL) whose delay time is 400ps, and a variable directional coupler (VDC). The balanced pulsepairs of double channels with measured delay times of 396ps and 398ps respectively were obtained in the conditions of both classical optics and single-photon transmissions. The chip has advantageous to achieve high interference visibilities of double channels simultaneously for BB84 phase and time-bin protocols.

The analysis of the foundations of modern cryptographic systems is carried out. Problems of classical cryptography arising in the development of quantum computers are considered. Considered are cryptographic protocols of quantum key distribution, their advantages and disadvantages. The analysis of stands for simulation of quantum key distribution available on the market is carried out. The rationale for the need to develop a training system has been made. The authors have developed a system for modeling and demonstrating quantum cryptographic protocols BB84, B92 and BB84 (4 + 2), intended for a detailed study of the principles of quantum cryptographic protocols in dynamics. The system provides the process of work both in text and graphic form. The developed system fully meets the needs of teaching students modern quantum information security technologies.

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.

The main purpose of quantum key distribution protocols is to provide a practical and secure transmission of the single-use key used in encryption at the sender and receiver side. In the classical method, both parties cannot be sure that the key has not been taken over by an attacker. Since the quantum key exchange method basically relies on quantum physics, it provides higher security than conventional key distribution methods. In this study, the first and most used BB84 protocol, which is one of the quantum key distribution (QKD) protocols, and the distribution of the key between the receiver and the sender in the simulation environment and the attempt of the attacker to achieve the key was performed in the simulation environment. The results obtained in the last section are analyzed and suggestions are made for future studies.

Quantum key distribution introduces a new way of key exchange through a public quantum channel between two communicating nodes. However, the first introduced BB84 protocol was theoretically verifying security based on single photon sources. At this time, it was hard to achieve such device. Therefore, it was a challenging aspect to prove the security of QKD system using coherent light sources or “multi emitting photon source”, which introduces Photon number splitting attacks. We are interested to simulate and investigate the QKD system using coherent laser sources and study the PNS attack. The idea involves that; Eve can crash a beam of light, absorbing some photons using QND measurement and transmit the others. Such attack can make Eve dominant to the situation and gain much information of the key without the fear of getting exposed to the communicating parties. Herein, this paper discusses some useful solution to detect such attack and proves the security of QKD even with weak laser sources.

Prepare-and-measure quantum key distribution (QKD) schemes with polarization encoding require the minimization of polarization degradation, i.e., undesired variations in the state of polarization, in the transmitter and receiver designs. In particular, the polarization extinction ratio (PER) should be maintained as high as possible to reduce the quantum bit error rate (QBER). In this paper, we analyze the polarization degradation and its correction in the design of free-space QKD systems. The polarization of a wavefront can be degraded in two different ways: uniformly, or non-uniformly; the latter known as polarization aberrations. While uniform polarization degradation of the beam wavefront can be easily corrected with standard retardation plates, polarization aberrations are more complex and require a different correction approach. BB84 diagonal linearly-polarized states are especially affected by polarization degradation as they are reflected off certain optical elements, and its correction is essential to achieve a low QBER. We have experimentally characterized the polarization degradation in a QKD transmitter and its impact in the QBER and achieved an almost perfect correction of the diagonal linearly polarized states when choosing a specific optical design.

Quantum key distribution from satellites becomes particularly valuable when it can be used on a large network and on-demand to provide a symmetric encryption key to any two nodes. A constellation model is described which enables QKD-derived encryption keys to be established between any two ground stations with low latency. This is achieved through the use of low earth orbit trusted-node QKD satellites which create a buffer of keys with the ground stations they pass over, and geostationary relay satellites to transfer secure combinations of the keys to the ground stations. Regional and global network models are considered and the use of inter-satellite QKD links for balancing keys is assessed.

Communication in the present information era needs to tread beyond the scopes of codes to provide security. If on one hand advances in encryption technology has made progress, the sanctity of conventional methods has also been breached time and again on the other. In search of a better security providing methodology, algorithms involving the principles of Quantum Key Distribution (QKD) have shown promising results. They use laws of physics to provide unprecedented information security while rendering a wide scope of being the next big breakthrough in the field. While QKD is subjected to ongoing research, several vulnerabilities have been encountered for its algorithms which need to be addressed with strong countermeasures, thereby making QKD practically robust for wide-range applications.

The problem of providing secrecy at quantum key distribution was analyzed. A two-pass self-compensation fiber-optic quantum key distribution system (QKDS) with phase coding photons states that operate on the BB84 protocol and implemented by the «plug&play» technology are reviewed. The synchronization process of quantum key distribution system and field test results of quantum cryptographic network basis on the QKDS Clavis2 are analyzed. Abstract strategies of unauthorized access to information in a quantum key distribution system by attacks such as “Trojan horse” and “Brute force” are described. One of the principles of protection the synchronization process of self-compensation quantum key distribution system from unauthorized access was described.

The field of quantum information is becoming more known to the general public. However, effectively demonstrating the concepts underneath quantum science and technology to the general public can be a challenging job. We investigate, extend, and much expand here “quantum candies” (invented by Jacobs), a pedagogical model for intuitively describing some basic concepts in quantum information, including quantum bits, complementarity, the no-cloning principle, and entanglement. Following Jacob’s quantum candies description of the well known quantum key distribution protocol BB84, we explicitly demonstrate various additional quantum cryptography protocols using quantum candies in an approachable manner. The model we investigate can be a valuable tool for science and engineering educators who would like to help the general public to gain more insights about quantum science and technology: most parts of this paper, including many protocols for quantum cryptography, are expected to be easily understandable by a layperson without any previous knowledge of mathematics, physics, or cryptography.

The authors present a comparison between the basic BB84 Quantum Key Distribution (QKD) and its optimised version based on Quantum Dense Coding, in terms of theoretical modelling and feasibility of circuits implementations. These circuits are mainly composed of probabilistic quantum gates, single photon sources, beam splitters (BSs), polarising BS and single photon detectors. They assume that the photonic devices composing the circuits are not perfect. They assess the average success probabilities of the two protocols depending on the success probability of the photonic sources used and the distance between Alice and Bob. They demonstrate that typical real-world photonic devices permit the implementation of secure communication with 0.65 of success probability over 120 km, while it could reach more than 0.9 over 148 km if just deterministic sources are provided.

With the development of the intelligent transportation system (ITS) and increasing application of vehicular ad-hoc networks (VANETs), the security of VANETs has become a crucial issue for VANETs and ITS. In this study, we propose a quantum VANETs protection scheme to address the security issue of vehicular identity authentication. It based on BB84 quantum key distribution protocol and quantum mechanics. Furthermore, the novel quantum scheme can defend most VANETs-aimed attacks. It also can be applied on connection of vehicle to everything (V2X), this is because reliability and security problem can be solved in proposed quantum scheme. By tactfully exploiting properties of quantum mechanics, our proposed scheme offers remarkable advantages which include remote identity authentication, identity revocation and irreversibility. The security analysis shows that our proposed scheme can further insure the security of VANETs identity authentication.

The present cryptography systems security depends on the hardness of factorizing an integer number with a large number of digits to its prime integer factors. In 1994, Peter Shor proposed a quantum procedure (Shor's algorithm) that easily factorizes large integer numbers to its prime factors compared with other algorithms. Consequently, present cryptography systems became endangered and once quantum computers exist, conventional cryptography systems could breakdown. On the other hand, quantum cryptography security is based on the well-known quantum mechanics uncertainty principle, and so the quantum cryptography enhances the cryptography field with a mechanism for eavesdropper detecting. Here, a hardware implementation was proposed for two types of key distribution protocols based on quantum computing, the one-way quantum key distribution protocol (BB84 protocol), and the two-way quantum key distribution protocol.

We report the first quantum key distribution (QKD) systems capable of delivering sustainable, real-time secure keys continuously at rates exceeding 10 Mb/s. To achieve such rates, we developed high speed post-processing modules, achieving maximum data throughputs of 60 MC/s, 55 Mb/s, and 108 Mb/s for standalone operation of sifting, error correction and privacy amplification modules, respectively. The photonic layer of the QKD systems features high-speed single photon detectors based on self-differencing InGaAs avalanche photodiodes, phase encoding using asymmetric Mach-Zehnder interferometer, and active stabilization of the interferometer phase and photon polarisation. An efficient variant of the decoy-state BB84 protocol is implemented for security analysis, with a large dataset size of $10^8$ bits selected to mitigate finite-size effects. Over a 2 dB channel, a record secure key rate of 13.72 Mb/s has been achieved averaged over 4.4 days of operation. We confirm the robustness and long-term stability on a second QKD system continuously running for 1 month without any user intervention., Comment: 7 pages, 8 figures, 1 table

Quantum key distribution is a secure way of transferring the keys among entities involved in communication. BB84 is the first protocol for QKD in year 1984. In this paper we are giving the simulati...

In this work, we represent the principle of quantum cryptography (QC) that is based on fundamental laws of quantum physics. QC or Quantum Key Distribution (QKD) uses various protocols to exchange a secret key between two communicating parties. This research paper focuses and examines the quantum key distribution by using the protocol BB84 in the case of encoding on the single-photon polarization and shows the influence of optical components parameters on the quantum key distribution. We also introduce Quantum Bit Error Rate (QBER) to better interpret our results and show its relationship with the intrusion of the eavesdropper called Eve on the optical channel to exploit these vulnerabilities.

We have developed an integrated polarization beam splitter (PBS) module with silica planar lightwave circuit technology for use in BB84 quantum key distribution (QKD). The PBS module is designed to operate on four linear polarizations of the horizontal/vertical/diagonal/antidiagonal direction, and shows the minimum polarization extinction ratio of 17.6 dB. When the module is loaded on the free-space BB84 QKD test-bed, quantum bit error rate and sifted key rate are 2.81% and 415 kb/s at clock rate of 100 MHz, respectively.

BB84 is a single photon that has been widely used since 1984 as the unconditional security of key distribution. Recently, the idea of multiphoton QKD was proposed to exchange the key using the rotational of polarization by over multi-stages protocol. By utilizing the state of polarization, the system does not require one of the four states like it did in the BB84 scheme. The multiphoton has the ability to improve the key rate generation and range of distances as well. Indeed, multiphoton QKD needs to be setup properly to gain the optimal performance over the fiber optic. This paper presents the fundamental implementation of multi-stages and multiphoton approach over the fiber optic by applying secret unitary transformation between Alice and Bob. The step by step operation of unitary transformation is applied using half-wave plates represented as Mueller matrix. This paper also evaluates the effects of parameters in the QKD model. The result reveals that channel loss, dark count rate, detector efficiency, photons' repetition rate, and the average number of photons will affect the QBER and SKR.

Untrusted node networks initially implemented by measurement-device-independent quantum key distribution (MDI-QKD) protocol are a crucial step on the roadmap of the quantum Internet. Considering extensive QKD implementations of trusted node networks, a workable upgrading tactic of existing networks toward MDI networks needs to be explicit. Here, referring to the nonstandalone (NSA) network of 5G, we propose an NSA-MDI scheme as an evolutionary selection for existing phase-encoding BB84 networks. Our solution can upgrade the BB84 networks and terminals that employ various phase-encoding schemes to immediately support MDI without hardware changes. This cost-effective upgrade effectively promotes the deployment of MDI networks as a step of untrusted node networks while taking full advantage of existing networks. In addition, the diversified demands on security and bandwidth are satisfied, and network survivability is improved.

Various imperfections of the hardware in quantum key distribution (QKD) lead to discrepancies between the theory and real-world devices. An eavesdropper can use these discrepancies to compromise the QKD security, thus legitimate sides need to estimate the influence of imperfections to prevent the loss of security. Here we investigate explicit eavesdropping attacks on passive side channels of the light source for a BB84 decoy states QKD protocol. We consider an optimal phase-covariant cloning attack, followed by unambiguous state discrimination and a joint measurement. Our calculations provide a hint that for state-of-the-art light sources the inherent presence of passive side channels still allows the protocol to be secure, albeit with the reduced secret key rates.

Passive generation of quantum states in quantum key distribution (QKD) is an elegant solution to utilise an internal source of quantum randomness of the transmitter’s scheme. It can be profitable, for example, in setups running at high repetition rates. However, the original analysis of passive protocol doesn’t consider real-life effects of a laser source, therefore possibly breaches the unconditional security of the scheme. Here we take into account the influence of various laser imperfections and make a refined comparison between active and passive setups. We show that the new bound on the secret key rate of the passive protocol stays similar to the one of an active scheme, thus proving passive generation to be a practical means of constructing QKD systems.

To increase the security and efficiency of information transmission, the technology of Quantum Key Distribution is developed. A simulation of secure key rate of BB84 protocol is done to give a visualized comparison of efficiency of the protocol using different light sources and detectors. The simulation shows that the Poisson light source is less efficient than single photon source and the secure key rate of using continuous variable detectors is lower than using discrete variable detectors.

Access control is a mechanism that is used to decide which agent has access to which resource with some specific operations. This paper is devoted to the investigation of quantum cryptography in access control. We develop three quantum protocols and use them for key distribution, identity authentication and digital certification, respectively. We analyze our protocols by the graphical language of categorical quantum mechanics. These protocols are unconditionally secure and implementable by the current technology.

It is found that there is the information leakage problem in the secure quantum dialogue (QD) protocol via cavity QED [Int J Theor Phys 54(3):772–779 (2015)]. To be specific, one out of the four bits about the secret messages is leaked out. Finally, an improved QD protocol without information leakage is put forward. It is sincerely hoped that researchers pay more attention to the information leakage problem in quantum secure communication to design truly secure protocols.

Based on quantum multi-proxy blind signature, a new E-payment protocol is proposed in this paper. Adopting the techniques of quantum key distribution, one-time pad and quantum proxy blind signature, our E-payment protocol could protect user’s anonymity as the traditional E-payment systems do, and also have unconditional security which the classical E-payment systems cannot provide. Additionally, the quantum operation can be transmitted successfully with the probability 1, which can make the protocol reliable and practical.

Quantum key distribution (QKD) is an innovative solution in the cryptography world to prevent the information leakage that can sometimes be deliberate. Several QKD protocols were recently presented for building a secure shared key, of which the BB84 protocol is one of those interesting protocols. The authentication between the communicating parties is one of the issues that cause a huge argument. Furthermore, the current well-known QKD protocols are not yet ready to realize the personality of either the sender or the receiver, although the QKD protocol is already protected by the rules of physics and quantum mechanics to detect any interruption. This paper introduces a new QKD protocol that utilizes two quantum channels to provide authenticated communications for legitimate parties. Moreover, the proposed QKD protocol uses two type of physical behaviors, entanglement and superposition states. The entangled states are utilized to confirm the authentication between the end users, while the superposition states carry the secret key that will be shared between the users.