QKD aims to banish man-in-the-middle eavesdropping of fiber networks.
Of all the announcements Verizon will make in 2020, the completion of a simple video trial between three offices in Washington D.C. might turn out to be the one people remember.
Completed in June but only made public last week, Verizon engineers streamed video from the company’s 5G Lab to screens at two offices two miles distant. It sounds mundane because the remarkable part of this demo was completely invisible – the background use of Quantum Key Distribution (QKD) to secure the communication.
QKD, or course, is a hugely demanding technology that’s spent the last 30 years being honed in physics labs around the world with the occasional proof-of-concept demo to record milestones such as new distance records and advancing bit rates.
Progress has inched forward, almost a matter of waiting for the telecom, fiber optic, and microprocessor technologies it needs to flourish to be invented. Then there’s the important issue of why anyone would want to use QKD at all. It’s this that’s suddenly become more pressing, and not simply for its effect on communications security.
Today’s secure communication depends on the distribution of asymmetric RSA encryption keys using a web of public key infrastructure (PKI). This creates two problems, the first of which is that an attacker in the middle can secretly intercept the keys and decrypt the data without anyone knowing.
QKD doesn’t stop an attacker intercepting the keys but makes it impossible for that eavesdropping to be hidden because doing so will introduce errors in a way guaranteed by the physics of quantum-entangled photons.
Although this should happen before any keys are sent, the second problem rears its head: a combination of Shor’s or Grover’s famous algorithms and the quantum computers that have evolved from them will at some point break RSA public key cryptography, rendering vast amounts of sensitive data encrypted with it over decades immediately vulnerable.
However, using QKD in conjunction with a second technology called Quantum Random Number Generation (QRNG) promises the ability to create symmetric encryption keys with enough entropy to resist being cracked by any quantum computer.
If you like, it’s a race between two quantum technologies – quantum computers on one side and the QKD/QRNG antidote on the other, with no prizes for coming second.
Quantum cybersecurity
It’s the latter that Verizon tested for the first time, which I understand reached a key bitrate of 1 megabit per second, modest considering the sites were only two miles away (the use of network repeaters could extend this to 60km).
“The initial trial was a point-to-point connection, but point-to-multipoint architectures are possible and may be integrated in a future enhancement,” director of Verizon technology development, Gina Otts, said via email.
P2P connections are the simplest because they use dedicated fiber links. Verizon’s press statement doesn’t say whether Verizon has started testing QKD communication multiplexed with other data on the same fiber – essential for practical QKD – although this has been tested by other carriers.
As to the underlying design used: “Verizon is evaluating multiple suppliers for both Quantum Key Distribution and Quantum Random Number Generation,” said Otts.
“Things are really taking off at the moment in QKD,” agrees Dr Andrew Shields, assistant managing director of Toshiba Labs in Cambridge UK, who has been working on QKD development since the 1990s.
“Now it’s getting to the stage where it can be used for commercial applications. We see a lot of interest from other telcos,” he adds, naming BT, Telefónica and Deutsche Telekom as companies trialing Toshiba’s own QKD system.
Toshiba’s system was now “plug-and-play,” able to slip into a standard networking rack with a 3U form factor, says Shields.
Shields mentions the OPENQKD project, a major pan-European QKD program to test interoperability between vendors raking place in cities including Cambridge, Madrid, Berlin, Vienna, and Geneva.
This, along with the EU’s 10-year Quantum Communication Infrastructure project will see QKD running over fiber and satellite networks expanded to cover Europe.
With investment in potentially huge 5G networks, Internet of Things (IoT), and secure banking upping the demand for security, “people want to have a quantum solution that won’t be threatened in the future. Many 5G trials are incorporating QKD,” agrees Shields.
Which is where we get to the sharp end of QKD because the technology’s future won’t just be about the joy of quantum mechanics. In addition to European efforts, the Chinese have invested heavily, setting several distance records for secure transmission over the last decade.
While the US is in the game too, some suspect China’s investment in both quantum computers and QKD might give it the edge in this new moonshot.
It all hinges on how easily issues such as resilience (the ability to resist denial of service attacks) authentication, and integration with key providers can be made to work. The race now is to get the technology out of the lab and into real networks. Solving those issues will take many more trials to build upon Verizon’s first tentative leap but there is little time to lose.
The country and carrier which can start using QKD in earnest – assuming that’s not already happened – will have a big advantage come the inevitable day quantum computers do their worst.
