A secret key agreement scheme with multi-level quantization and parity check using fluctuation of radio channel property

2008 ◽  
Author(s):  
Shimpei Yasukawa ◽  
Hisato Iwai ◽  
Hideichi Sasaoka
Keyword(s):  
Key Agreement ◽  
Radio Channel ◽  
Parity Check ◽  
Secret Key ◽  
Multi Level ◽  
Secret Key Agreement ◽  
Level Quantization

Information reconciliation for QKD

2011 ◽  
Vol 11 (3&4) ◽  
pp. 226-238
Author(s):  
David Elkouss ◽  
Jesus Martinez-Mateo ◽  
Vicente Martin
Keyword(s):  
Quantum Key Distribution ◽  
Key Agreement ◽  
Information Leakage ◽  
Error Rates ◽  
Parity Check ◽  
Random String ◽  
Secret Key ◽  
Information Reconciliation ◽  
Low Density Parity Check ◽  
Secret Key Agreement

Quantum key distribution (QKD) relies on quantum and classical procedures in order to achieve the growing of a secret random string ---the key--- known only to the two parties executing the protocol. Limited intrinsic efficiency of the protocol, imperfect devices and eavesdropping produce errors and information leakage from which the set of measured signals ---the raw key--- must be stripped in order to distill a final, information theoretically secure, key. The key distillation process is a classical one in which basis reconciliation, error correction and privacy amplification protocols are applied to the raw key. This cleaning process is known as information reconciliation and must be done in a fast and efficient way to avoid cramping the performance of the QKD system. Brassard and Salvail proposed a very simple and elegant protocol to reconcile keys in the secret-key agreement context, known as \textit{Cascade}, that has become the de-facto standard for all QKD practical implementations. However, it is highly interactive, requiring many communications between the legitimate parties and its efficiency is not optimal, imposing an early limit to the maximum tolerable error rate. In this paper we describe a low-density parity-check reconciliation protocol that improves significantly on these problems. The protocol exhibits better efficiency and limits the number of uses of the communications channel. It is also able to adapt to different error rates while remaining efficient, thus reaching longer distances or higher secure key rate for a given QKD system.

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