Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Quantum cryptography theory has a proven security defect

Abstract:
Researchers at Tamagawa University, Quantum ICT Research Institute, (Director: Osamu Hirota, 6-1-1 Tamagawa Gakuen, Machida, Tokyo, Japan), announced today that they had proved the incompleteness and limit of the security theory in quantum key distribution. They showed that the present theory cannot guarantee unconditional security. Details will be described at the SPIE conference on Quantum Communication and Quantum Imaging held in San Diego on August 15, 2012.

Quantum cryptography theory has a proven security defect

Tokyo, Japan | Posted on August 7th, 2012

Until now, the majority of researchers in quantum information science have believed that quantum cryptography (quantum key distribution) can provide unconditional security. The guarantee of its unconditional security is given by the trace distance, which is a quantum version of the evaluation of a mathematical cipher. However, since 2006, new developments in the field have cast criticism over the meaningful security of cryptography ensured only by the trace distance. Despite these criticisms, many papers have continued to claim that the trace distance guarantees unconditional security in quantum key distribution.

Researchers at Quantum ICT have now succeeded in clarifying a logical path between the present theory and criticisms of it. Consequently, they have proved that the present theory does not work to quantify security, and cannot provide the unconditional security given in Shannon's theory, the theory that rigorously defines the security for an unbreakable cipher.

The details of this work will be presented at the SPIE conference on Quantum Communication and Quantum Imaging held in San Diego on August 15, 2012.

The title of the talk is "Incompleteness and Limit of Quantum Key Distribution Theory".

**************************************************************************

Result Summary

Many papers claim that the trace distance, d, guarantees unconditional security in quantum key distribution (QKD). In our paper, first we explain explicitly the main misconception in the claim of unconditional security for QKD theory. In general terms, the cause of the misunderstanding in the security claim is the Lemma in Renner's paper. It suggests that the generation of a perfect random key is assured by the probability (1-d), and that its failure probability is d. Thus, it concludes that the generated key provides a perfect random key sequence when the protocol succeeds. In this way QKD provides perfect secrecy (unconditional security) to a type of encryption termed ‘the one-time pad'.

H. P. Yuen at Northwestern University proved that the trace distance quantity does not give the probability of such an event. If d is not small enough, the generated key sequence is never perfectly random. The evaluation of the trace distance now requires reconstruction if it is to be used. However, QKD theory groups have not accepted this criticism, and have invented many upper-bound evaluation theories for the trace distance.

We clarified that the most recent upper bound theories for the trace distance are constructed again by the reasoning of Renner, who originally introduced the concept. It is thus unsuitable to quantify the information theoretic security of QKD, and the unconditional security defined by Shannon is not satisfied.

Consequently, Yuen's theory is correct, and at present there is no theoretical proof of the unconditional security for any QKD.

Background

Quantum information science holds enormous promise for entirely new kinds of computing and communications, including important problems that are intractable using conventional digital technology. The most expected field is quantum cryptography. But realizing that promise will depend on theoretical guarantee of the security and the ability to transfer an extremely fragile quantum condition. Recently it has been pointed out sometimes that, in general, scientists are not familiar with practical applications. The quantum cryptography (quantum key distribution: QKD) is a typical example of the stern realities.

Now, despite enormous progress in theoretical QKD, many theory groups are still discussing the security proof for QKD based on Renner's trace distance theory. One of reasons is that H.P.Yuen (Northwestern University) pointed out that the present theory does not guarantee the security of the real QKD system [1,2].

Recently, Renner et al announced that in any practical implementation, the generated key length is limited by the available resources, and the present security proofs are not established rigorously in such a situation. And they published own improvement result in Nature Communication in 2012 [3]. However, without the review of the incompleteness of the theory, it is repeatedly and persistently claimed that a specific trace distance criterion would guarantee unconditional security in QKD. And, unfortunately, almost all the theory groups on QKD ignored the criticisms. This is disagreeable in the development of science and technology. Researchers are obliged to clarify "what is going on" in the discussion of the scientific theory.

At present, there is no review on such a dispute. Our purpose is to clarify a story of the argument on the recent theory of QKD and the criticism against them. We introduced the Shannon theory on the cryptography to confirm the basis of the concept of the unconditional security. And we compared the fundamental concept of the current security theory of QKD by R.Renner and. the outline of the Yuen's criticism. Finally, we provided evidence on which there is no theoretical proof of the unconditional security for any QKD, despite that many theoretical papers claimed the perfect proof of the unconditional security.

[1] H.P.Yuen, Key generation: Foundation and a new quantum approach,

IEEE J. Selected topics in Quantum Electronics, vol-15, no-6, pp1630-1645, 2009.

[2] H.P.Yuen, Fundamental quantitative security in quantum key distribution,

Physical Review A, vol-82, 062304, 2010.

[3] M.Tomamichel, C.Lim, N.Gisin, and R.Renner, Tight finite-key analysis for quantum cryptography,

Nature Communication, vol-3, p639, 2012.

####

About Tamagawa University, Quantum ICT Research Institute
Tamagawa K-12 & University was founded in 1929 as an elementary education organization. Later secondary education divisions were added, and in 1947 Tamagawa University received approval for establishment as an "old system" (pre-war) university. As a comprehensive institution (gakuen), we currently provide education from kindergarten to graduate school level within a single campus.

For more information, please click here

Contacts:
Osamu Hirota
Director
Quantum ICT Research Institute
Tamagawa University
6-1-1 Tamagawa Gakuen
Machida, Tokyo, 194-8610, Japan

Copyright © Tamagawa University, Quantum ICT Research Institute

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

NanoTechnology for Defense (NT4D) October 22nd, 2014

Mechanism behind nature's sparkles revealed October 22nd, 2014

TARA Biosystems and Harris & Harris Group Form Company to Improve Safety and Efficacy of New Therapies October 22nd, 2014

Researchers patent a nanofluid that improves heat conductivity October 22nd, 2014

Law enforcement/Anti-Counterfeiting/Security/Loss prevention

Superconducting circuits, simplified: New circuit design could unlock the power of experimental superconducting computer chips October 18th, 2014

IRLYNX and CEA-Leti to Streamline New CMOS-based Infrared Sensing Modules Dedicated to Human-activities Characterization October 15th, 2014

Nanoparticles give up forensic secrets October 2nd, 2014

Light detector to revolutionise night vision technology September 8th, 2014

Discoveries

Mechanism behind nature's sparkles revealed October 22nd, 2014

Researchers patent a nanofluid that improves heat conductivity October 22nd, 2014

‘Designer’ nanodevice could improve treatment options for cancer sufferers October 22nd, 2014

Detecting Cancer Earlier is Goal of Rutgers-Developed Medical Imaging Technology: Rare earth nanocrystals and infrared light can reveal small cancerous tumors and cardiovascular lesions October 21st, 2014

Announcements

NanoTechnology for Defense (NT4D) October 22nd, 2014

Mechanism behind nature's sparkles revealed October 22nd, 2014

TARA Biosystems and Harris & Harris Group Form Company to Improve Safety and Efficacy of New Therapies October 22nd, 2014

Researchers patent a nanofluid that improves heat conductivity October 22nd, 2014

Events/Classes

NanoTechnology for Defense (NT4D) October 22nd, 2014

Ucore's McKenzie to Deliver Presentation to Rare Earths Conference in Singapore as Highlight of Fall 2014 Marketplace Schedule October 19th, 2014

Aspen Aerogels, Inc. Schedules Third Quarter 2014 Earnings Release and Conference Call for November 6, 2014 October 17th, 2014

New VDMA Association "Electronics, Micro and Nano Technologies" founded: Inaugural Meeting in Frankfurt/Main, Germany October 15th, 2014

NanoNews-Digest
The latest news from around the world, FREE





  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE