Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Linköping University researchers break "unbreakable" crypto

16.04.2008
Quantum cryptography has been regarded as 100-percent protection against attacks on sensitive data traffic. But now a research team at Linköping University in Sweden has found a hole in this advanced technology.

The risk of illegal accessing of information, for example in money transactions, is necessitating more and more advanced cryptographic techniques.

When you send an encrypted message via the computer network, one of the most difficult problems to solve is how the key should be transmitted. One way is to send it by courier (either by regular mail or, as in spy movies, a person with a briefcase attached to his wrist). Another way is a "public key," which is used for online banking and security functions in Web browsers (https://).

A courier must of course be reliable, otherwise there is a risk that the key will be secretly copied on the way. A public key is regarded as secure, since enormous calculations are required to break the long strings of data bits - some 2,000 - that make up the key.

But a new technology called quantum cryptography is supposed to be absolutely secure. Thus far, however, very few people have made use of it. It requires special hardware, for example with a type of laser that emits polarized light particles (photons) via optic fiber or through the air. Some companies and banks in Austria are testing the system, and trials are underway with satellite-TV transmission.

The security is guaranteed by the laws of quantum mechanics.
Quantum-mechanical objects have the peculiar property that they cannot be measured upon or manipulated without being disturbed. If somebody tries to copy a quantum-cryptographic key in transit, this will be noticeable as extra noise. An eavesdropper can cause problems, but not extract usable information.

But Jan-Åke Larsson, associate professor of applied mathematics at Linköping University, working with his student Jörgen Cederlöf, has shown that not even quantum cryptography is 100-percent secure. There is a theoretical possibility that an unauthorized person can extract the key without being discovered, by simultaneously manipulating both the quantum-mechanical and the regular communication needed in quantum cryptography.

"The concern involves authentication, intended to secure that the message arriving is the same as the one that was sent. We have scrutinized the system as a whole and found that authentication does not work as intended. The security of the current technology is not sufficient," says Jan-Åke Larsson.

In the article, published in the prestigious journal IEEE Transactions on Information Theory, the authors propose a change that solves the problem.

"We weren't expecting to find a problem in quantum cryptography, of course, but it is a really complicated system. With our alteration, quantum cryptography will be a secure technology," says Jan-Åke Larsson.

Contact: Jan-Åke Larsson, phone: +46 (0)13-281468; e-mail: jalar@mai.liu.se

Åke Hjelm | alfa
Further information:
http://www.liu.se

More articles from Information Technology:

nachricht First machine learning method capable of accurate extrapolation
13.07.2018 | Institute of Science and Technology Austria

nachricht A step closer to single-atom data storage
13.07.2018 | Ecole Polytechnique Fédérale de Lausanne

All articles from Information Technology >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Research finds new molecular structures in boron-based nanoclusters

13.07.2018 | Materials Sciences

Algae Have Land Genes

13.07.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>