Original URL: http://www.theregister.co.uk/2013/06/07/temporal_cloaking_offers_the_ultimate_in_data_security/

'Time cloak' can hide data - but not the fact there's something to hide

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By Bill Ray

Posted in Science, 7th June 2013 11:56 GMT

Holes created in light can hide data beyond the wit of any thief, who won't even know it's there thanks to the latest temporal cloaking technique. Or so we're told.

The idea here is to split light, with its wavering signal, into component wavelengths, then offset those wavelengths such that they cancel each other out. Anyone intercepting the beam will see nothing - or an unwavering signal - where the cancelling is in effect, resulting in communications swathed in a temporal cloak.

The work, carried out at Purdue University and published in leading boffinry mag Nature, follows on from a 2010 experiment which used the optical properties of different types of fibre to create holes in the signal. That work used a lens to split the light by colour, then push it into a fibre which let red move faster than blue creating a gap, a different fibre at the other end lets blue move faster so closing the gap.

That approach creating very small gaps, the reconstruction left no evidence: which meant the receiving party wouldn't know about the hidden data either, rather limiting the cryptographic value of the process.

This time the gaps are bigger, up to 90 per cent of the signal, and the kit needed comes off the shelf.

Anyone wanting to intercept the signal could try to disentangle the wavelengths again, assuming he knew what was happening. The timing is a solvable challenge, and the kit is standard, but that's not stopped widespread reports that the technique heralds a new era of enhanced security.

Concealing communications is old hat, Ultra-Wideband radio is indistinguishable from noise unless you know what you're looking for, and even basic frequency hopping can make a signal hard to see, but most miscreants in this league will know what they're doing - certainly anyone prepared to cut into a fibre line will - so pretending there's no signal is probably not going to work.

Hiding signals is also not very important these days. Decent encryption is all but unbreakable: when encrypted data is stolen it's inevitably down to poor implementation, leaked keys or a happy combination of the two. Governments may have need for better security, but they too know that the quickest way to decrypt something is to find someone with the key and hit them until they tell you.

So the experiment is fascinating, and may well have application in making light more robust - phased signals should prove easier to reconstruct so increasing range or throughput - but when it comes to security the ability to drop one's data into a time hole isn't quite as useful as it sounds cool. ®