Cited by 8,299Quantum Information and CryptographyCryptography and Data SecurityWireless Communication Security Techniques

The DOI matches its Crossref record; 6 of the 6 references it cites were found in a registry or an index; none of the 6 sources its claims cite is checked for support yet.

Quantum cryptography: Public key distribution and coin tossing

Open access
Bennett, Charles H., Brassard, Gilles·2014·Theoretical Computer Science

Abstract

When elementary quantum systems, such as polarized photons, are used to transmit digital information, the uncertainty principle gives rise to novel cryptographic phenomena unachievable with traditional transmission media, e.g. a communications channel on which it is impossible in principle to eavesdrop without a high probability of disturbing the transmission in such a way as to be detected. Such a quantum channel can be used in conjunction with ordinary insecure classical channels to distribute random key information between two users with the assurance that it remains unknown to anyone else, even when the users share no secret information initially. We also present a protocol for coin-tossing by exchange of quantum messages, which is secure against traditional kinds of cheating, even by an opponent with unlimited computing power, but ironically can be subverted by use of a still subtler quantum phenomenon, the Einstein-Podolsky-Rosen paradox.

Overview

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TL;DR

The paper introduces quantum cryptography using non-orthogonal polarized photon states to distribute a secret random key between users who initially share no secret, with eavesdropping detectable in principle. It also presents a quantum coin-tossing protocol secure against traditional cheating even with unlimited computing power, except for a theoretical EPR-based attack requiring perfect photon storage and detection.

Key findings

  • In quantum key distribution, an eavesdropper informed of a photon’s original basis only after measuring it can obtain at most 1/2 expected bits about the key bit; any measurement yielding \(b\) bits (\(b \le 1/2\)) must induce disagreement with probability at least \(b/2\) when the photon is later re-measured in its original basis. The optimum tradeoff example: measuring and retransmitting all intercepted photons rectilinearly learns the correct polarizations of half the photons and induces disagreements in 1/4 of those later re-measured in the original basis.
  • Alice and Bob can test for eavesdropping by publicly comparing a random subset—say one third—of correctly received bits; if comparisons agree, the remaining same-basis bits can be used as a one-time pad.
  • For coin tossing, Alice sends about one thousand random bits encoded in one basis; Bob guesses the basis; Alice reveals the basis and her original bit string; Bob verifies against his rectilinear and diagonal tables. The honest protocol gives each party exactly 50 per cent chance of winning.
  • Cheating by Bob would require guessing Alice’s basis with probability greater than 1/2, which would imply distinguishing randomly polarized photon trains and enable faster-than-light communication via the Einstein-Podolsky-Rosen effect. Alice can cheat using EPR photon pairs, but this requires perfect efficiency of storage and detection of photons, beyond current technology.

Methods

  • Theoretical protocol design and security analysis based on quantum mechanics of single polarized photons, Hilbert-space formalism, conjugate rectilinear and diagonal bases, the uncertainty principle, and the no-cloning theorem.
  • Quantum key distribution protocol: Alice sends random bits in randomly chosen bases; Bob measures randomly in one of the two bases; public classical discussion identifies successful same-basis bits; optional Wegman-Carter authentication can relax the need for an active-eavesdropping-immune public channel if a small secret key is shared.
  • Coin-tossing protocol: Alice sends a photon train in one basis, Bob guesses the basis, Alice reports the actual basis and certifies by revealing her original bit sequence, and Bob verifies against his two measurement tables. The paper provides illustrative examples but no empirical data.

Limitations

  • Stated: quantum transmissions are necessarily very weak and cannot be amplified in transit; quantum cryptography does not provide digital signatures, certified mail, or the ability to settle disputes before a judge.
  • Stated: the public channel must be immune to active eavesdropping unless Alice and Bob share a small secret key for Wegman-Carter authentication; an eavesdropper can still suppress communication, though users can detect suppression with high probability.
  • Stated: the EPR cheating attack is merely theoretical because it requires perfect efficiency of photon storage and detection, beyond current technology; the honestly followed protocol could be realized with current technology. Evident from the text: no experimental implementation or empirical data are reported, and the security arguments are theoretical.

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Integrity signals

Registry

Crossref · 10.1016/j.tcs.2014.05.025

Cites

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Claims the paper makes

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  • The quote only partly states this claim. 4
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  • The authors state this as an assumption.

    The public classical channel used in the protocol is susceptible to eavesdropping but not to injection or alteration of messages.

    “susceptible to eavesdropping but not to the injection or alteration of messages.”
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Citations

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Research works printed but not linked: 1

  1. David Bohm, Quantum Theory (Prentice-Hall, Englewood Cliffs, NJ, 1951), pp. 614–619.

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Metadata

Authors
Bennett, C. H., & Brassard, G.
Affiliations
IBM (United States) (US)
Corresponding author
Bennett, Charles H.
Venue
Theoretical Computer Science
Publisher
Elsevier BV
Published
2014-12
Volume
560
Pages
7-11
ISSN
0304-3975 (ISSN-L)
OpenAlex
W2015179126
Cited by
8,299
References
6
Citations by year
2026: 479 · 2025: 773 · 2024: 554 · 2023: 518 · 2022: 463 · 2021: 616 · 2020: 519 · 2019: 512 · 2018: 374 · 2017: 377 · 2016: 326 · 2015: 343 · 2014: 308
FWCI
449.98
Type
journal article
Language
en
Open access
Locations
  • Theoretical Computer Science (publishedVersion, cc-by-nc-nd)
  • arXiv (Cornell University) (submittedVersion)
  • arXiv (Cornell University)
Topics
  • Physical Sciences › Physics and Astronomy › Atomic and Molecular Physics, and Optics › Quantum Information and Cryptography
  • Physical Sciences › Computer Science › Computer Networks and Communications › Cryptography and Data Security
  • Physical Sciences › Engineering › Electrical and Electronic Engineering › Wireless Communication Security Techniques
Keywords
quantum cryptography, public key distribution, quantum key distribution, polarized photons, uncertainty principle, eavesdropping detection, quantum channel security, EPR paradox

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