One of the objectives of information security is to maintain the confidentiality and integrity of the information by ensuring that information is transferred in a way that is secure from any listener or attacker. There was no comparison experiment conducted in earlier studies regarding different level encoding performance towards multiphoton technique. Multiphoton technique in the earlier study is particular to transmission time for data transfer encoding and extra time for polarizers to change polarisation angles, both of which contribute to longer transmission times. With four different size of qubits, the three simulation experiments are carried out using Python coding with 2,4 and 8 levels of encoding. Experiment results demonstrate that the most efficient average photon transmission derived from 18 qubit size ranges from 98.71% to 98.73% depending on encoding level. With 18 qubit size, the four-level encoding result has the highest average efficiency, followed by the eight-level and two-level encodings, respectively. 4-level encoding exhibits the highest average photon efficiency between 2 and 8 level encoding.
One of the objectives of information security is to maintain the confidentiality and integrity of the information by ensuring that information is transferred in a way that is secure from any listener or attacker. There was no comparison experiment conducted in earlier studies regarding different level encoding performance towards multiphoton technique. Multiphoton technique in the earlier study is particular to transmission time for data transfer encoding and extra time for polarizers to change polarisation angles, both of which contribute to longer transmission times. With four different size of qubits, the three simulation experiments are carried out using Python coding with 2,4 and 8 levels of encoding. Experiment results demonstrate that the most efficient average photon transmission derived from 18 qubit size ranges from 98.71% to 98.73% depending on encoding level. With 18 qubit size, the four-level encoding result has the highest average efficiency, followed by the eight-level and two-level encodings, respectively. 4-level encoding exhibits the highest average photon efficiency between 2 and 8 level encoding.
Quantum secure direct communication (QSDC) is a branch of quantum cryptography which exploits laws of physics and was recently proposed for securing information transferred from sender to receiver without relying on computational complexity. Instead of an entangled photon, the quantum cryptography employs two other approaches, single photon and multiphoton for encoding the messages. The multiphoton was proposed to outperform the weaknesses of a single photon by introducing the multiplicity of a photon to perform data encryption tasks. Despite the advantages of multiphoton, the transmission time to transfer the encoded data is still regarded as a critical issue. Most of the multiphoton approaches require multiple photons to travel along a number of stages. Moreover, extra time is needed to change the polarization angle of the optical device for encoding purposes. These situations have resulted in an increase in source redundancy, which subsequently leads to an increase in the transmission time. In this paper, a compression message approach is proposed to mitigate the substantial increase in time used for the data transmission processes. The proposed compression approach, namely, hybrid M-ary in a braided single stage (HMBSS) is based on the lossless data encoding such that the number of photons is reduced in the data transmission stage. Extensive simulation experiments have been conducted to test the performance of the proposed approach against some selected multiphoton approaches. The results show that the proposed approach outperforms braided single-stage, M-ary three-stage and initialization vector in terms of reducing total average transmission time to encode the photon by about 75.9% and 91.7%, respectively. Furthermore, the HMBSS reduces the overhead on the transmission channel by minimizing the number of message's bits by about 45% in average even when the length of the message increases during the transmission as compared to others.
It was recently proposed to use quantum secure direct communication (QSDC), a branch of quantum cryptography, to secure data transfers from sender to receiver without relying on computational complexity. Despite the benefits of multiphoton, sending secret messages between several parties in a quantum channel still presents a challenge because the current multiphoton only considers two parties. When more parties are included, the scalability problem becomes apparent. Therefore, the scalable multiphoton approach is needed to allow secure sharing between the legal parties. The manipulation of level encoding provides new opportunities for more efficient quantum information processing and message sharing. This research aims to propose a strategy that uses four-level encoding with the multiphoton approach to share secret messages between multi-party. From the analysis conducted, it has been shown that a high number of level encoding can shorten the time taken for photon transmission between parties and an attacker has a lower probability of chances to launch an attack, however, communication will be affected due to high sensitivity to noise.
In order to mitigate the problem of low transmission rate and limited communication distance in Quantum Communication (QCs), multiphoton over multi-stages approach has been proven to be a possible alternative to the conventional single photon approach. Multiphoton has the ability to improve the range of distances and key generation rate over multi-stages photon transmission. However, the determination of optimal mean photon numbers and number of stages in multiphoton approach remains a key challenge to make the protocols well utilized during their operations. Following this concern, three problems and their corresponding proposed solutions in this thesis are presented below: Firstly, the existing multiphoton approaches involve multiple photons to travel throughout a number of stage. Furthermore, extra time is required to update the polarization angle of optical device for encoding purposes. These conditions would result in an increase in the total transmission time of the photons to be transmitted over the quantum channel. Accordingly, a Hybrid M-Ary in Braided Single-Stage (HMBSS) approach by utilizing data compression concept is proposed to address these issues. In HMBSS, the sender is able to compress the secret message using Huffman encoding over the braided single-stage operation. This compression mechanism has reduced the number of bits required to represent a string of symbols, thereby reducing the time to encode the photons. The simulation experiments shows that HMBSS achieved promising result by 75.9% and 91.7% total average transmission time decrease as compared to the well-known Multiphoton-BSS, Multiphoton-M-ary and Multiphoton-TSIV. Secondly, providing strong authentication is the main focus in this research which aims to make multiphoton QC secure against variety types of attacks. Current authentication procedure in multiphoton QC requires public agreement to pre-share the authentication key and secret angles before onset of the transmission, therefore increasing the communication cost. As a solution, a Secure Secret Authentication Key (SSAK) is proposed. In SSAK, the quantum handshake scheme is used to share initial secret polarization angle and authentication key which is utilized before quantum communication session. The results of simulation experiments reveal that SSAK significantly outperformed the Three-stage protocol in terms of average covered angle by Eve. The simulation experiments and security analysis of initial authentication and transmission of messages verified that an eavesdropper is unable to disclose any information about the transmitted message or the authentication key. Lastly, most of the proposed QKD protocol employs a single-beam set up to transmit the photons over the free space optic which results in low bit rate and limited distance coverage due to high impact of geometrical loss. To deal with this, a transmission technique of Multiphoton Quantum Communication using multiple beam concept (MQC-MB) is proposed. Comparison is conducted in terms of total loss and received power on different number of beam shows that 4-beam is acceptable to be adapted in MQC-MB. The statistical analysis shows that such approach has reduced the total attenuation by 6dB compared to single-beam setup.
A one-way quantum secure direct communication protocol with quantum identification utilizing two-photon three-qubit linear cluster states is proposed. The protocol can be used to transmit a secret message and identify user's identification simultaneously. The transmission of information is instantaneous, i.e. the information can be decoded during the transmission and no final transmission of additional information is needed. We prove its robustness against attacks: Any attempt of an adversary to obtain information (and even a bit of information) necessarily induces some errors that the legitimate parties could notice, even in noisy environments. Moreover, this protocol achieves a high efficiency and source capacity since more qubits can be encoded on the same photon.
This dissertation presents a study of the security and performance of a quantum communication system using multi-stage multi-photon tolerant protocols. Multi-stage protocols are a generalization of the three-stage protocol proposed in 2006 by Subhash Kak. Multi-stage protocols use “Polarization Hopping,” which is the process of changing the polarization state at each stage of transmission. During the execution of a multi-stage protocol, the message transfer always starts by encoding a bit of information in a polarization state; for example, bit 0 is encoded using state |0⟩ and bit 1 is encoded using state|1⟩ whereas, on the channel, the state of polarization is given by α|├ 0⟩┤+β|├ 1⟩┤. In the following α and β are restricted to the real numbers i.e., the polarization stays on the equator of the Poincare sphere. A transformation applied by one communicating party at a given stage will result in new values of α and β. \nThis dissertation analyzes the security of multi-stage, multi-photon tolerant protocols and proposes an upper bound on the average number of photons per pulse in the cases where Fock states and the cases where coherent states are used in the implementation of the three-stage protocol. The derived average number of photons is the maximum limit at which the three-stage protocol can operate at a quantum secure level while operating in a multi-photon domain. In addition, this dissertation studies the vulnerability of the multi-stage protocol to the Trojan horse attack, Photon Number splitting attack (PNS), Amplification attack, as well as the man-in-the middle attack. Moreover, this dissertation proposes a modified version of the multi-stage protocol. This modified version uses an initialization vector and implements a chaining mode between consecutive implementations of the protocol. The modified version is proposed in the case of the three-stage protocol and named a key/message expansion four variables three-stage protocol. The proposed nomenclature is based on the fact that an additional variable is added to secure the three-stage protocol. The introduction of this additional variable has the potential to secure the multi-stage protocol in the multi-photon regime. It results in the eavesdropper having a set of simultaneous equations where the number of variables exceeds the number of equations. \nThe dissertation also addresses the performance of the multi-stage, multi-photon tolerant protocol. An average photon number of 1.5 photon/stage is used to calculate the maximum achievable distance and key transfer rates while using the single-stage protocol over fiber optic cables. We compute the increase in distance as well as data transfer rate while using the single-stage protocol. Channel losses as well as the detector losses are accounted for. \nFinally, an application of the multi-stage protocol in IEEE 802.11 is proposed. This application provides wireless networks with a quantum-level of security. It proposes the integration of multi-stage protocols into the four-way handshake of IEEE 802.11.
By studying the properties of the mixture of Bell state particles and single photons,in the paper we design a quantum code scheme with high coding capacity,and propose a novel quantum secure direct communication protocol with high transmission efficiency.Alice prepares Bell state particles and single photons,and divides Bell state particles into two sequences SA and SB.SB is sent to Bob for the first security check through using quantum correlation properties of particles.When the check result shows that the quantum channel is safe,by using the designed quantum code scheme, Alice encodes her classical message on the mixed quantum state sequence of Bell sequence SA and single photon sequence SS.Then,some single photons that are used for security check are re-inserted randomly into the encoded sequence,and the order of particles is rearranged to ensure checking Eve's attack.Alice sends the new sequence to Bob.Bob delays and receives it.And then,the quantum channel conducts the second-time security check.The transmission error rate is calculated,and if the error rate is lower than the tolerance threshold,the channel is safe.Bob decodes and reads Alice's message.The first security check is to determine whether quantum channel is safe.The second security check is to test whether there are eavesdroppers during information transmission.Safety analysis is done by applying the quantum information theory for the proposed protocol.The error rate introduced by Eve and the amount of information by Eve are calculated.It is shown that this pro-tocol can effectively resist measurement-resend attack,intercept-resend attack, auxiliary particle attack,denial of service attack and Trojan attack.Among them,auxiliary particle attack is analyzed in detail.The transmission efficiency and coding capacity are also analyzed.The transmission efficiency is 2,the quantum bit rate is 1,and the coding capacity is that a quantum state can encode three bits of classical messages.We also compare the proposed protocol with many existing popular protocols in the sense of efficiency,e.g.,Ping-Pong protocol, Deng F G et al.'s two-step and one-pad-time quantum secure direct communication protocol,Wang J et al.'s quantum secure direct communication protocol based on entanglement swapping and Quan D X et al.'s one-way quantum secure direct communication protocol based on single photon.It is proved that this proposed protocol has higher transmission efficiency.In addition,neither complex U operation nor entanglement swapping is used,and implementation process is simplified.However,this protocol is devoted to theoretical research of quantum secure direct communication.There are still some difficulties in the practical application.For example,the storage technology of quantum states is not mature at present.It is not easy to prepare and measure Bell state particles nor to combine them with single photons,and so on.The implementation of this protocol depends on the development of quantum technology in the future.