121 research outputs found
Blind Reconciliation
Information reconciliation is a crucial procedure in the classical
post-processing of quantum key distribution (QKD). Poor reconciliation
efficiency, revealing more information than strictly needed, may compromise the
maximum attainable distance, while poor performance of the algorithm limits the
practical throughput in a QKD device. Historically, reconciliation has been
mainly done using close to minimal information disclosure but heavily
interactive procedures, like Cascade, or using less efficient but also less
interactive -just one message is exchanged- procedures, like the ones based in
low-density parity-check (LDPC) codes. The price to pay in the LDPC case is
that good efficiency is only attained for very long codes and in a very narrow
range centered around the quantum bit error rate (QBER) that the code was
designed to reconcile, thus forcing to have several codes if a broad range of
QBER needs to be catered for. Real world implementations of these methods are
thus very demanding, either on computational or communication resources or
both, to the extent that the last generation of GHz clocked QKD systems are
finding a bottleneck in the classical part. In order to produce compact, high
performance and reliable QKD systems it would be highly desirable to remove
these problems. Here we analyse the use of short-length LDPC codes in the
information reconciliation context using a low interactivity, blind, protocol
that avoids an a priori error rate estimation. We demonstrate that 2x10^3 bits
length LDPC codes are suitable for blind reconciliation. Such codes are of high
interest in practice, since they can be used for hardware implementations with
very high throughput.Comment: 22 pages, 8 figure
Rate Compatible Protocol for Information Reconciliation: An application to QKD
Information Reconciliation is a mechanism that allows to weed out the
discrepancies between two correlated variables. It is an essential component in
every key agreement protocol where the key has to be transmitted through a
noisy channel. The typical case is in the satellite scenario described by
Maurer in the early 90's. Recently the need has arisen in relation with Quantum
Key Distribution (QKD) protocols, where it is very important not to reveal
unnecessary information in order to maximize the shared key length. In this
paper we present an information reconciliation protocol based on a rate
compatible construction of Low Density Parity Check codes. Our protocol
improves the efficiency of the reconciliation for the whole range of error
rates in the discrete variable QKD context. Its adaptability together with its
low interactivity makes it specially well suited for QKD reconciliation
- …