Feeds

Quantum crypto backdoor closed

Cambridge boffins patch photon-splitting vuln

Choosing a cloud hosting partner with confidence

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. ®

Intelligent flash storage arrays

More from The Register

next story
Webcam hacker pervs in MASS HOME INVASION
You thought you were all alone? Nope – change your password, says ICO
You really need to do some tech support for Aunty Agnes
Free anti-virus software, expires, stops updating and p0wns the world
USB coding anarchy: Consider all sticks licked
Thumb drive design ruled by almighty buck
Attack reveals 81 percent of Tor users but admins call for calm
Cisco Netflow a handy tool for cheapskate attackers
Privacy bods offer GOV SPY VICTIMS a FREE SPYWARE SNIFFER
Looks for gov malware that evades most antivirus
Patch NOW! Microsoft slings emergency bug fix at Windows admins
Vulnerability promotes lusers to domain overlords ... oops
prev story

Whitepapers

Why cloud backup?
Combining the latest advancements in disk-based backup with secure, integrated, cloud technologies offer organizations fast and assured recovery of their critical enterprise data.
A strategic approach to identity relationship management
ForgeRock commissioned Forrester to evaluate companies’ IAM practices and requirements when it comes to customer-facing scenarios versus employee-facing ones.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
Managing SSL certificates with ease
The lack of operational efficiencies and compliance pitfalls associated with poor SSL certificate management, and how the right SSL certificate management tool can help.
Saudi Petroleum chooses Tegile storage solution
A storage solution that addresses company growth and performance for business-critical applications of caseware archive and search along with other key operational systems.