SOFT-PROCESSING FOR INFORMATION RECONCILIATION IN QKD APPLICATIONS

2011 ◽  
Vol 09 (supp01) ◽  
pp. 155-164 ◽  
Author(s):  
MARINA MONDIN ◽  
MARIA DELGADO ◽  
FABIO MESITI ◽  
FRED DANESHGARAN

In this manuscript, a composite channel model for quantum key distribution is considered, including both a "hard output" quantum channel and a "soft output" classic channel. The metrics derived from the two channels are jointly processed at the receiver, exploiting capacity achieving soft-metric based iteratively decoded block codes, and soft-information based information reconciliation and privacy amplification techniques are proposed. The performance of the proposed mixed-soft-metric algorithms is analyzed as a function of the system parameters.

2018 ◽  
Vol 18 (9&10) ◽  
pp. 795-813
Author(s):  
Sunghoon Lee ◽  
Jooyoun Park ◽  
Jun Heo

Quantum key distribution (QKD) is a cryptographic system that generates an information-theoretically secure key shared by two legitimate parties. QKD consists of two parts: quantum and classical. The latter is referred to as classical post-processing (CPP). Information reconciliation is a part of CPP in which parties are given correlated variables and attempt to eliminate the discrepancies between them while disclosing a minimum amount of information. The elegant reconciliation protocol known as \emph{Cascade} was developed specifically for QKD in 1992 and has become the de-facto standard for all QKD implementations. However, the protocol is highly interactive. Thus, other protocols based on linear block codes such as Hamming codes, low-density parity-check (LDPC) codes, and polar codes have been researched. In particular, reconciliation using LDPC codes has been mainly studied because of its outstanding performance. Nevertheless, with small block size, the bit error rate performance of polar codes under successive-cancellation list (SCL) decoding with a cyclic redundancy check (CRC) is comparable to state-of-the-art turbo and LDPC codes. In this study, we demonstrate the use of polar codes to improve the performance of information reconciliation in a QKD system with small block size. The best decoder for polar codes, a CRC-aided SCL decoder, requires CRC-precoded messages. However, messages that are sifted keys in QKD are obtained arbitrarily as a result of a characteristic of the QKD protocol and cannot be CRC-precoded. We propose a method that allows arbitrarily obtained sifted keys to be CRC precoded by introducing a virtual string. Thus the best decoder can be used for reconciliation using polar codes and improves the efficiency of the protocol.


2012 ◽  
Vol 10 (03) ◽  
pp. 1250032 ◽  
Author(s):  
PIOTR ZAWADZKI

A modified version of the well known ping-pong protocol is proposed and analyzed in the paper. The operation of the improved version exploits inevitable errors introduced by the eavesdropping in the message mode — a feature which has not been exploited so far. A proposed protocol improvement is in its role similar to the privacy amplification known from the quantum key distribution schemes, but no randomization of transferred information is introduced and deterministic character of communication is preserved. Messages are processed in blocks which guarantees that an eavesdropper is faced with a computationally infeasible problem as long as the system parameters are within reasonable limits. Information processing does not require quantum memory registers and confidential communication is possible without prior key agreement or some shared secret.


2021 ◽  
Vol 21 (3&4) ◽  
pp. 0181-0202
Author(s):  
Khodakhast Bibak ◽  
Robert Ritchie ◽  
Behrouz Zolfaghari

Quantum key distribution (QKD) offers a very strong property called everlasting security, which says if authentication is unbroken during the execution of QKD, the generated key remains information-theoretically secure indefinitely. For this purpose, we propose the use of certain universal hashing based MACs for use in QKD, which are fast, very efficient with key material, and are shown to be highly secure. Universal hash functions are ubiquitous in computer science with many applications ranging from quantum key distribution and information security to data structures and parallel computing. In QKD, they are used at least for authentication, error correction, and privacy amplification. Using results from Cohen [Duke Math. J., 1954], we also construct some new families of $\varepsilon$-almost-$\Delta$-universal hash function families which have much better collision bounds than the well-known Polynomial Hash. Then we propose a general method for converting any such family to an $\varepsilon$-almost-strongly universal hash function family, which makes them useful in a wide range of applications, including authentication in QKD.


2017 ◽  
Vol 37 (2) ◽  
pp. 0227002
Author(s):  
刘翼鹏 Liu Yipeng ◽  
郭建胜 Guo Jiansheng ◽  
崔竞一 Cui Jingyi

2014 ◽  
Vol 560 ◽  
pp. 46-61 ◽  
Author(s):  
Marco Lucamarini ◽  
Stefano Mancini

Author(s):  
Jonathan C Denton ◽  
Douglas D Hodson ◽  
Richard G Cobb ◽  
Logan O Mailloux ◽  
Michael R Grimaila ◽  
...  

This work presents a model to estimate the performance of space-based, optical-based, quantum communication protocols. This model consists of components to account for optical channel propagation effects based on orbit selection and atmospheric conditions. The model presented is general purpose and can be leveraged to evaluate the performance of a variety of quantum communication protocols, of which, Quantum Key Distribution (QKD) systems served as our motivating use case of particular interest. To verify correctness, the model is used to produce estimates for QKD system scenarios and compared to published results. The performance of QKD systems is of interest as distance limitations for terrestrial-based systems have hindered their practical use, and satellite-based designs that can generate a shared key between two distant geographic locations have been proposed. For this application domain, a review of space-based designs that illuminate the need for a free space downlink channel model is presented followed by its development to estimate the performance of quantum exchanges between a satellite and ground site.


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