Feeds

Optical boffins cut the cost of quantum cryptography

Time shift dances the light fantastic

Choosing a cloud hosting partner with confidence

Boffins at the National Institute of Standards and Technology are trialling advanced optical techniques aimed at reducing the price of quantum cryptography systems.

The new quantum key distribution approach reduces the required number of single photon detectors, which can cost anything between $5K-$20K and are the most costly component of quantum cryptography systems.

Quantum cryptography allows two users on an optical fibre network to exchange secret keys. Each bit of the key is encoded upon a single light particle (or 'photon'). Intercepting this data randomly changes the polarization of the light, irreversibly altering the data.

Because of this quantum mechanics effect any attempt by an eavesdropper to determine a key corrupts the same key with noise. Quantum cryptography systems discard these corrupt keys and only use codes that are known to be secure. These quantum keys, once exchanged, can be used in a one-time pad.

Conventional cryptography setups involve at least two photon detectors, and more commonly four. By adding an optical component that delays the travel of photons to the detector, NIST researchers have been able to halve the number of detectors needed.

The most common polarization-based protocol, BB84, uses four single-photon detectors. One pair of detectors looks for photons with either vertical or horizontal polarization, which signify either 0 or 1. The other set of detectors record diagonally polarized photons.

NIST researchers have reduced the number of detectors required by using an optical component to make these diagonally polarized photons rotate by a further 45 degrees and arrive at the horizontal/vertical detector, but slightly later than photons that started off with this orientation. As such the approach is a type of time division multiplexing.

The same technique was used to number of detectors needed to implement the B92 protocol from two to one.

The approach cuts transmission rates by half but the advantage of lower costs far outweighs this minor disadvantage. The NIST team, led by researcher Xiao Tang, reckon the approach avoids introducing noise and might actually be more secure than conventional approaches.

NIST researchers intend to explain their detection time bin shift (DTBS) scheme in a paper due to be published by the IEEE Communications Letters next month.

In additional research carried out after the publication of this paper, the NIST team has further developed its approach so that the popular BB84 protocol requires only one detector instead of four.

A summary of the research, including diagrams, can be found on the NIST website. ®

Beginner's guide to SSL certificates

More from The Register

next story
Russian hackers exploit 'Sandworm' bug 'to spy on NATO, EU PCs'
Fix imminent from Microsoft for Vista, Server 2008, other stuff
FYI: OS X Yosemite's Spotlight tells Apple EVERYTHING you're looking for
It's on by default – didn't you read the small print?
Microsoft pulls another dodgy patch
Redmond makes a hash of hashing add-on
'LulzSec leader Aush0k' found to be naughty boy not worthy of jail
15 months home detention leaves egg on feds' faces as they grab for more power
Kill off SSL 3.0 NOW: HTTPS savaged by vicious POODLE
Pull it out ASAP, it is SWISS CHEESE
Facebook slurps 'paste sites' for STOLEN passwords, sprinkles on hash and salt
Zuck's ad empire DOESN'T see details in plain text. Phew!
Admins! Never mind POODLE, there're NEW OpenSSL bugs to splat
Four new patches for open-source crypto libraries
prev story

Whitepapers

Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
Cloud and hybrid-cloud data protection for VMware
Learn how quick and easy it is to configure backups and perform restores for VMware environments.
Three 1TB solid state scorchers up for grabs
Big SSDs can be expensive but think big and think free because you could be the lucky winner of one of three 1TB Samsung SSD 840 EVO drives that we’re giving away worth over £300 apiece.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.