Chaotic Quantum Key Distribution

Round 1

Reviewer 1 Report

Unconditional Security is a basic and essential property in Quantum Key distribution system. This paper applies an idea of Chaotic signals to enhance the practical security of Quantum Key Distribution. Specifically to overcome the photon number splitting attack ‌in the BB84 protocol. It is an interesting approach where authors have considered an chaotic QKD approach and applied new encoding/decoding based on Chaotic signal to overcome existing experimental challenges in the present QKD systems. While this approach is not entirely novel, there are several bits of novelty especially in regards to limiting Eve's secret key accessibility.  

 

I think the paper would benefit from a discussion about why Chaotic encoding is so good at avoid Photon number splitting attack compare to existing optical chaotic schemes. It's important to understand this for many reasons. First, it tells us something about the relevance of the encoding and decoding to the QKD protocol. Second, it might tell us something about the evasion resilience of the proposed Chaotic QKD protocol. These two points are really important to cover as part of the revision process.  please consider and add the following reference. do Nascimento, José Cláudio, R. L. C. Damasceno, G. L. de Oliveira, and Rubens Viana Ramos. "Quantum-chaotic key distribution in optical networks: from secrecy to implementation with logistic map." Quantum Information Processing 17, no. 12 (2018): 329.  

 

Otherwise, the paper is fairly good. If the recommended analysis is included, it would definitely be worth publishing. As of now it's not clear why the Chaotic encoding and decoding is working so well to make QKD system more secure.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

The submitted work proposes a new approach to the implementation of a quantum key distribution system using synchronized chaos bypassing side-channel attacks. This is an interesting and relevant work that demonstrates a new perspective under study of quantum information. The protocol is described in sufficient detail and can be implemented, which is reported in the final part of the work.
Among the shortcomings of the work, I would like to note the redundant introduction with a simplified but too detailed description of the well-known protocol. Nevertheless, a brief analysis of side-channel attacks (such as photon number splitting) with existing countermeasures is not presented yet, hence the advantage of the proposed solution regarding countermeasures is not obvious. So it will be enough at this stage of research to make at least several references to such works. There are also schemes where the security proof takes into account the use of a weak coherent laser, not a single-photon source. They are also worth mentioning.
I can recommend this work for publication only if authors will correct the indicated shortcomings and make the necessary additions.

Author Response

Point 1: 
 a brief analysis of side-channel attacks (such as photon number splitting) with existing countermeasures is not presented yet, hence the advantage of the proposed solution regarding countermeasures is not obvious. So it will be enough at this stage of research to make at least several references to such works. There are also schemes where the security proof takes into account the use of a weak coherent laser, not a single-photon source. They are also worth mentioning. 

 

Response 1: Thank you very much for your insightful feedback. The addition of a short review of the other methods proposed to mitigate side channel attacks is important to give a full background of the solutions to this problem. To this end I have added a section outlined in black addressing your comments (line 55-59 and 72-81). I have provided a description of a common decoy state method and talked about its application and implementation drawbacks. I have done this to provide further incentive for the proposed communication protocol.

As for the proofs of security considering the use of weak coherent lasers the work, I have referenced a work defining the security parameters for a weak coherent source. In this polarization encoding was discussed, but with a stricter requirement on the state preparation, namely that appropriate phases must be selected for the security of the protocol to be applied. In the proposed protocol, the security is foundationally provided by the incomplete knowledge an eavesdropper has on the communication. Meaning no such phase association is required in the state preparation. This allows for a simpler implementation of communication schemes while still supplying robust security.

Reviewer 3 Report

The paper is well written. The topic is really relevant. This paper explore a novel application of quantum key distribution and synchronized chaos which is utilized to mask a transmitted message. Some pictures are of low resolution. Quantum key distribution systems have a synchronization process. This process precedes the quantum protocol key distribution process. It is not entirely clear whether the author is considering this process of synchronization, or he proposes a modification of the quantum protocol ..? I would recommend inserting a sentence or two to clarify this. I recommend using the following literature sources:

[1] Anton Pljonkin, Pradeep Kumar Singh. The Review of the Commercial Quantum Key Distribution System. 2018 Fifth International Conference on Parallel, Distributed and Grid Computing. Publisher: IEEE. DOI: 10.1109/PDGC.2018.8745822

Author Response

Point 1: Quantum key distribution systems have a synchronization process. This process precedes the quantum protocol key distribution process. It is not entirely clear whether the author is considering this process of synchronization, or he proposes a modification of the quantum protocol ..? I would recommend inserting a sentence or two to clarify this. I recommend using the following literature sources: 


 

Response 1: Thank you very much for your insightful suggestions, the additions to the paper made from your suggestions are outlined in red (line 112-116). In the protocol application I assumed as a given that this would occur, but I do believe it is worth mentioning to avoid confusion. Therefore, I have added a step to the protocol that addresses this problem. Synchronization of the transmitter and receiver is imperative to successful QKD and without this no correlation between sent and received photon could be made. So, upon your suggestion I have added a section to the paper describing this and made use of the reference you provided.

Round 2

Reviewer 1 Report

I am satisfied with the authors responses and the improved quality of the manuscript. It can be accepted in its current form for publication in Cryptography Journal.