Feeds

Quantum crypto backdoor closed

Cambridge boffins patch photon-splitting vuln

5 things you didn’t know about cloud backup

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. ®

Secure remote control for conventional and virtual desktops

More from The Register

next story
One HUNDRED FAMOUS LADIES exposed NUDE online
Celebrity women victimised as Apple iCloud accounts reportedly popped
Goog says patch⁵⁰ your Chrome
64-bit browser loads cat vids FIFTEEN PERCENT faster!
Rubbish WPS config sees WiFi router keys popped in seconds
Another day, another way in to your home router
NIST to sysadmins: clean up your SSH mess
Too many keys, too badly managed
Scratched PC-dispatch patch patched, hatched in batch rematch
Windows security update fixed after triggering blue screens (and screams) of death
Researchers camouflage haxxor traps with fake application traffic
Honeypots sweetened to resemble actual workloads, complete with 'secure' logins
Attack flogged through shiny-clicky social media buttons
66,000 users popped by malicious Flash fudging add-on
New Snowden leak: How NSA shared 850-billion-plus metadata records
'Federated search' spaffed info all over Five Eyes chums
Three quarters of South Korea popped in online gaming raids
Records used to plunder game items, sold off to low lifes
prev story

Whitepapers

Endpoint data privacy in the cloud is easier than you think
Innovations in encryption and storage resolve issues of data privacy and key requirements for companies to look for in a solution.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Advanced data protection for your virtualized environments
Find a natural fit for optimizing protection for the often resource-constrained data protection process found in virtual environments.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
Next gen security for virtualised datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.