7,833 research outputs found
A Generic Security Proof for Quantum Key Distribution
Quantum key distribution allows two parties, traditionally known as Alice and
Bob, to establish a secure random cryptographic key if, firstly, they have
access to a quantum communication channel, and secondly, they can exchange
classical public messages which can be monitored but not altered by an
eavesdropper, Eve. Quantum key distribution provides perfect security because,
unlike its classical counterpart, it relies on the laws of physics rather than
on ensuring that successful eavesdropping would require excessive computational
effort. However, security proofs of quantum key distribution are not trivial
and are usually restricted in their applicability to specific protocols. In
contrast, we present a general and conceptually simple proof which can be
applied to a number of different protocols. It relies on the fact that a
cryptographic procedure called privacy amplification is equally secure when an
adversary's memory for data storage is quantum rather than classical.Comment: Analysis of B92 protocol adde
The Role of Quantum Cryptography under Distributed Protocols for Secured Communication in Ad Hoc Networks
Most of the cryptographic methods employed so far has been using symmetric and asymmetric cryptography, and had involved cryptographic keys extensively. Usually it is observed that many of the cryptographic algorithms are infeasible as the key distribution system is feeble. As an emerging approach Ad Hoc networks is subjected to Quantum cryptography concept or quantum key distribution in distributed environment and has drawn a good attention as an appropriate solution to the Key Distribution issue. QKD extends unconditional secured inter-communication by means of quantum mechanics. The paper focuses on quantum theory as a substitute to conventional key distribution protocols and a comprehensive narration is offered illustrating implementations of quantum key distribution protocols. This paper depicts quantum key distribution protocols (QKDP) to preserve safety in large and Ad hoc networks, guiding towards novel direction. It is aimed to narrate the efficiency of communication in terms of effort, security, suitability and confidentiality by the use of QKDPs
Finite key size analysis of two-way quantum cryptography
Quantum cryptographic protocols solve the longstanding problem of
distributing a shared secret string to two distant users by typically making
use of one-way quantum channel. However, alternative protocols exploiting
two-way quantum channel have been proposed for the same goal and with potential
advantages. Here we overview a security proof for two-way quantum key
distribution protocols, against the most general eavesdropping attack, that
utilize an entropic uncertainty relation. Then, by resorting to the `smooth'
version of involved entropies, we extend such a proof to the case of finite key
size. The results will be compared to those available for one-way protocols
showing some advantages
Experimental investigation of high-dimensional quantum key distribution protocols with twisted photons
Quantum key distribution is on the verge of real world applications, where
perfectly secure information can be distributed among multiple parties. Several
quantum cryptographic protocols have been theoretically proposed and
independently realized in different experimental conditions. Here, we develop
an experimental platform based on high-dimensional orbital angular momentum
states of single photons that enables implementation of multiple quantum key
distribution protocols with a single experimental apparatus. Our versatile
approach allows us to experimentally survey different classes of quantum key
distribution techniques, such as the 1984 Bennett \& Brassard (BB84),
tomographic protocols including the six-state and the Singapore protocol, and
to investigate, for the first time, a recently introduced differential phase
shift (Chau15) protocol using twisted photons. This enables us to
experimentally compare the performance of these techniques and discuss their
benefits and deficiencies in terms of noise tolerance in different dimensions.Comment: 13 pages, 4 figures, 1 tabl
Vulnerabilities in Quantum Key Distribution Protocols
Recently proposed quantum key distribution protocols are shown to be
vulnerable to a classic man-in-the-middle attack using entangled pairs created
by Eve. It appears that the attack could be applied to any protocol that relies
on manipulation and return of entangled qubits to create a shared key. The
protocols that are cryptanalyzed in this paper were proven secure with respect
to some eavesdropping approaches, and results reported here do not invalidate
these proofs. Rather, they suggest that quantum cryptographic protocols, like
conventional protocols, may be vulnerable to methods of attack that were not
envisaged by their designers.Comment: 6 pages, 1 figur
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
Implementation vulnerabilities in general quantum cryptography
Quantum cryptography is information-theoretically secure owing to its solid
basis in quantum mechanics. However, generally, initial implementations with
practical imperfections might open loopholes, allowing an eavesdropper to
compromise the security of a quantum cryptographic system. This has been shown
to happen for quantum key distribution (QKD). Here we apply experience from
implementation security of QKD to several other quantum cryptographic
primitives. We survey quantum digital signatures, quantum secret sharing,
source-independent quantum random number generation, quantum secure direct
communication, and blind quantum computing. We propose how the eavesdropper
could in principle exploit the loopholes to violate assumptions in these
protocols, breaking their security properties. Applicable countermeasures are
also discussed. It is important to consider potential implementation security
issues early in protocol design, to shorten the path to future applications.Comment: 13 pages, 8 figure
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