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Researchers in Germany had the Alphasat I-XL communications satellite send laser beams in the infrared range to a measuring station located 38,000km away, on the holiday island of Tenerife. They then analysed the light quanta of the laser beam, thus generating a code to be used to read an encrypted message. — dpa |
Researchers turn to the universe in the name of quantum cryptography
Quantum computing is one of those terms likely to make the hair of data privacy activists stand on end.
The development of these superfast computers is progressing rapidly, and one day, they are expected to become so powerful that they'll be able to crack encryption methods commonly used today in a flash.
Experts say that in as little as 10 to 15 years' time, quantum computing could be capable of deciphering what is now considered secure: banking and healthcare data in the private sector, but also highly sensitive information of governments and military institutions. That's why encryption experts are now looking for alternatives.
One of them makes use of satellites in space.
The first few quantum computers already exist. It's difficult to estimate when they will reach their critical scale, says Frank Termer, software division manager at German IT association Bitkom.
The new computers are little marvels. "They can be used to dramatically accelerate computing processes," says Termer. "Instead of years, they may only take hours or less."
However, this will leave current security and encryption procedures vulnerable.
"In order not to be outpaced by this development, the preparations for the post-quantum period must begin today," says the German Office for Information Security (BSI) on progress in quantum computing.
Researchers at the Max Planck Institute for the Science of Light in Erlangen, Germany, are picking up the gauntlet.
"Our goal is to be faster than the developments threatening us," says the institute's Christoph Marquardt. Along with his colleagues, he is conducting research on so-called quantum cryptography.
This method is based on the laws of quantum physics. A photon, also known as a light quantum, can only be measured completely once.
There's a reason for this: The procedure itself changes the state of the particle, leading to a different result in a second examination.
This basic idea can be used to encrypt information.
A transmitter sends photons to a receiver. Together, they can then create a secret code that can be used to read encrypted information.
This technique is considered to be safe from eavesdropping, because any attempt to secretly read the code leaves traces in the signals, making it obvious immediately.
One of the biggest problems so far has been the distance over which information can be transmitted using quantum cryptography, Marquardt explains.
Although there are already companies offering quantum communication via fibre optic cables, the quality of the signal diminishes significantly beyond a distance of around 100km, making it necessary to amplify it.
The issue is, this won't work with quantum technology.
However, one can take a detour through space to keep interference to a minimum. "There is absorption in the atmosphere," says Marquardt. "But it's only 10km thick. After that, there's a vacuum."
The researchers are taking advantage of this fact: They had the Alphasat I-XL communications satellite send laser beams in the infrared range to a measuring station located 38,000 kilometres away, on the holiday island of Tenerife.
In collaboration with the company Tesat-Spacecom based in Backnang, Germany, and the German Aerospace Center, Marquardt and his team then analysed the light quanta of the laser beam, thus generating the code that can be used to read an encrypted message.
Marquardt stresses that Alphasat I-XL wasn't originally built for quantum communication.
Something akin to a coincidence enabled the researchers to carry out the tests: A colleague joined the Max Planck Institute after working for Tesat-Spacecom, a provider of laser-assisted satellite communications.
He had noticed that the technology used there was a good match for the laboratory experiments conducted by the institute.
"We can use existing systems," says Marquardt. Now it's about making quantum cryptography affordable using satellites.
In five to 10 years, a whole cluster of satellites could communicate on a quantum basis, both with each other and with base stations.
But the essential prerequisite for all the delicate issues surrounding data protection remains: "You'll have to trust the operator of the satellite." — dpa
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