Blind information reconciliation with variable step sizes for quantum key distribution

Abstract

Quantum key distribution (QKD) generates symmetric keys between two authenticated parties with the guarantee of information-theoretically security. A vital step in QKD to obtain fully-matched key between two parties is information reconciliation. the blind reconciliation protocol provides a useful tool that corrects the mismatch in a wide range of qubit error rate (QBeR) but without a prior error estimation. However, there is a contradiction between the reconciliation efficiency and the processing time in this protocol. in this work, we propose a blind reconciliation protocol with variable step sizes to relieve this contradiction. the analysis and simulation results show that the improved protocol inherits all the advantages of the original blind reconciliation protocol and can obtain better reconciliation efficiency with less operation time. The improved blind reconciliation protocol enhances the final secret key rate and accelerates the processing speed of a QKD system.Quantum key distribution (QKD) 1,2 allows two parties, usually called Alice and Bob, to share a pair of secret key via an insecure channel. QKD is proved to be information-theoretically secure owing to the solid foundation of quantum physics without computational assumptions 3-5 . The technology of QKD has been developed quickly in the past three decades and has achieved remarkable milestones. For example, QKD products has been commercialized with growing market 6 ; QKD networks has been constructed in several countries around the world 7-9 ; a QKD satellite realizes secure communication in global scale 10,11 . Thus, QKD is one of the most mature fields in quantum information.In the implementation of QKD, a system operates two main phases to establish the shared key -the phase of quantum raw key exchange and the phase of classical post-processing 12 . At the first phase, Alice and Bob share the raw key by transmitting quantum states prepared by Alice through a quantum channel and measuring them by Bob. Then, sifting as the first step of classical post-processing helps Alice and Bob to maintain the cases that they are using the matched bases. The raw key is obtained after this step. However, the raw key shared between Alice and Bob may contain errors due to the channel noise and adversary's attacks. To eliminate the mismatch of the raw key between Alice and Bob, the system runs information reconciliation to guarantee that the same string of key shared at both sides. The reconciled key maybe partially correlated with an adversary, since the adversary can interact with the quantum states during the raw key exchange via quantum channel and listen to the public information during the information reconciliation via the classical channel. Thus, privacy amplification is applied to remove the leaked information, thereby obtaining the final secret key share between Alice and Bob. The sifting, information reconciliation, and privacy amplification are called as the post-processing phase.In the post-processing, it is obvious that information reconciliation is...

Blind information reconciliation with polar codes for quantum key distribution

“…Moreover, additional optimizations and fine-tuning of parameters (e.g. varying of step size in a way as it was implemented for LDPC codes version [17]), can be also considered.…”

“…Information reconciliation methods proposed so far mainly rely on the Cascade method [7][8][9] or low-density parity-check (LDPC) codes [10][11][12][13][14][15][16][17]. The latter approach has been studied in various aspects and it is used in commercial QKD devices.…”

High-Efficient Syndrome-Based LDPC Reconciliation for Quantum Key Distribution

“…In addition, this protocol could achieve high efficiencies within a wider QBER range even with frame-length of 2 kb, which made it suitable for hardware implementations. Later in [26], an increasing number instated of a fixed number of punctured bits were revealed in each additional communication round. With the help of this optimization, Bob could receive increasing help from Alice in the later communication round, thereby the convergence of IR was accelerated.…”

Error Reconciliation based on Integer Linear Programming in Quantum Key Distribution

“…If QBER is higher than the determined threshold, because of the nocloning theorem [10], it shows that Eve spoofs the connection and the key is not safe anymore. Otherwise, the next step is begun, 3-B uses a reconciliation algorithm [11][12][13][14][15][45][46][47] to correct the errors and then uses some privacy amplification methods [16,17] to remove the disclosed information along the reconciliation step. Key reconciliation is important because using an efficient approach with minimum information leakage, in addition to increase secure key generation rate, it impacts on the security of the communication between two sides.…”