Feeds

Quantum crypto backdoor closed

Cambridge boffins patch photon-splitting vuln

High performance access to file storage

Researchers believe they have secured a potential backdoor in a cryptography technique known as Quantum Key Distribution (QKD).

The QKD method involves the use of laser diodes to transmit crypto keys along fibre optic lines as streams of light quanta – individual photons. Any attempt to eavesdrop on the transmission involves measuring it in some way at a quantum level, which will necessarily alter the transmitted data and reveal to the communicating parties that the key is compromised.

The scientists at the Toshiba Research Europe Labs at Cambridge found that the laser diodes sometimes transmitted an extra photon in response to an energy pulse designed to elicit only one. This would allow an attacker to measure the second photon and leave the first untouched, potentially reading the secret key without being rumbled. This problem was especially prevalent when using stronger pulses so as to increase the rate at which key data could be sent.

But a team bossed by Dr Andrew Shields, Quantum Information group leader at Toshiba Research Europe, has stymied such so-called "pulse-splitting" attacks by introducing lower-intensity "decoy photons" to verify that a transmission is unmonitored.

According to Shields and his team, these decoy pulses seldom have a trailing partner and as such are impossible to read covertly. The communicating parties can use the decoys to check that no eavesdropping has taken place, so be assured that their higher-intensity, higher-bandwidth multiphoton stream of keys is uncompromised.

"Using these new methods for QKD we can distribute many more secret keys per second, while at the same time guaranteeing the unconditional security of each," says Shields. "This enables QKD to be used for a number of important applications such as encryption of high bandwidth data links."

QKD can now transmit at 5.5kbits/sec over a 25km optical fibre, a hundred times the previous rate.

Shields' crew has also, in a further burst of enthusiasm, rendered its own research ultimately irrelevant. The team has developed a new class of nano-diodes which are so small – at 45nm across – they can contain only a few electrons. This means they can only ever emit a single photon at the selected wavelength, so sidestepping the multi-photon minefield entirely. ®

High performance access to file storage

More from The Register

next story
Obama allows NSA to exploit 0-days: report
If the spooks say they need it, they get it
Parent gabfest Mumsnet hit by SSL bug: My heart bleeds, grins hacker
Natter-board tells middle-class Britain to purée its passwords
Web data BLEEDOUT: Users to feel the pain as Heartbleed bug revealed
Vendors and ISPs have work to do updating firmware - if it's possible to fix this
OpenSSL Heartbleed: Bloody nose for open-source bleeding hearts
Bloke behind the cockup says not enough people are helping crucial crypto project
One year on: diplomatic fail as Chinese APT gangs get back to work
Mandiant says past 12 months shows Beijing won't call off its hackers
Call of Duty 'fragged using OpenSSL's Heartbleed exploit'
So it begins ... or maybe not, says one analyst
German space centre endures cyber attack
Chinese code retrieved but NSA hack not ruled out
Experian subsidiary faces MEGA-PROBE for 'selling consumer data to fraudster'
US attorneys general roll up sleeves, snap on gloves
prev story

Whitepapers

Securing web applications made simple and scalable
In this whitepaper learn how automated security testing can provide a simple and scalable way to protect your web applications.
Five 3D headsets to be won!
We were so impressed by the Durovis Dive headset we’ve asked the company to give some away to Reg readers.
HP ArcSight ESM solution helps Finansbank
Based on their experience using HP ArcSight Enterprise Security Manager for IT security operations, Finansbank moved to HP ArcSight ESM for fraud management.
The benefits of software based PBX
Why you should break free from your proprietary PBX and how to leverage your existing server hardware.
Mobile application security study
Download this report to see the alarming realities regarding the sheer number of applications vulnerable to attack, as well as the most common and easily addressable vulnerability errors.