52,667 research outputs found
Estimates for practical quantum cryptography
In this article I present a protocol for quantum cryptography which is secure
against attacks on individual signals. It is based on the Bennett-Brassard
protocol of 1984 (BB84). The security proof is complete as far as the use of
single photons as signal states is concerned. Emphasis is given to the
practicability of the resulting protocol. For each run of the quantum key
distribution the security statement gives the probability of a successful key
generation and the probability for an eavesdropper's knowledge, measured as
change in Shannon entropy, to be below a specified maximal value.Comment: Authentication scheme corrected. Other improvements of presentatio
Eavesdropping on practical quantum cryptography
Practical implementations of quantum cryptography use attenuated laser pulses
as the signal source rather than single photons. The channels used to transmit
are also lossy. Here we give a simple derivation of two beam-splitting attacks
on quantum cryptographic systems using laser pulses, either coherent or mixed
states with any mean photon number. We also give a simple derivation of a
photon-number splitting attack, the most advanced, both in terms of performance
and technology required. We find bounds on the maximum disturbance for a given
mean photon number and observed channel transmission efficiency for which a
secret key can be distilled. We start by reviewing two incoherent attacks that
can be used on single photon quantum cryptographic systems. These results are
then adapted to systems that use laser pulses and lossy channels.Comment: to appear in J. Mod. Op
Quantum cryptography: key distribution and beyond
Uniquely among the sciences, quantum cryptography has driven both
foundational research as well as practical real-life applications. We review
the progress of quantum cryptography in the last decade, covering quantum key
distribution and other applications.Comment: It's a review on quantum cryptography and it is not restricted to QK
Quantum cryptography: a practical information security perspective
Quantum Key Exchange (QKE, also known as Quantum Key Distribution or QKD)
allows communicating parties to securely establish cryptographic keys. It is a
well-established fact that all QKE protocols require that the parties have
access to an authentic channel. Without this authenticated link, QKE is
vulnerable to man-in-the-middle attacks. Overlooking this fact results in
exaggerated claims and/or false expectations about the potential impact of QKE.
In this paper we present a systematic comparison of QKE with traditional key
establishment protocols in realistic secure communication systems.Comment: 5 pages, new title, published version, minor changes onl
Beating the PNS attack in practical quantum cryptography
In practical quantum key distribution, weak coherent state is often used and
the channel transmittance can be very small therefore the protocol could be
totally insecure under the photon-number-splitting attack. We propose an
efficient method to verify the upper bound of the fraction of counts caused by
multi-photon pluses transmitted from Alice to Bob, given whatever type of Eve's
action. The protocol simply uses two coherent states for the signal pulses and
vacuum for decoy pulse. Our verified upper bound is sufficiently tight for QKD
with very lossy channel, in both asymptotic case and non-asymptotic case. The
coherent states with mean photon number from 0.2 to 0.5 can be used in
practical quantum cryptography. We show that so far our protocol is the
decoy-state protocol that really works for currently existing set-ups.Comment: So far this is the unique decoy-state protocol which really works
efficiently in practice. Prior art results are commented in both main context
and the Appendi
- …