Nuclear physics powering Cybersecurity?
Imagine an world in which our devices, websites, emails, passwords and personal information are completely hacker-proof.
Sounds too good to be true? Perhaps not.
In the future, unhackable, tamper-proof encryption systems based on quantum mechanics could help keep our data safe from prying eyes, said Dr Alexander Ling, Principal Investigator at the National University of Singapore’s Centre for Quantum Technologies (CQT).
Dr Ling was speaking at a session on cybersecurity at EmTech Asia, a conference organised by the MIT Technology Review on global emerging technologies, held in Singapore from 14-15 February 2017.
Present-day encryption methods are based on mathematical algorithms. These have worked reasonably well so far because they are difficult to crack using conventional computing technology.
But as computers become more and more powerful, such systems are no longer as unbreakable as they used to be.
“At some point, we have to think about moving to a new encryption scheme,” said Dr Ling.
He and others are working on ways of using quantum mechanics — the branch of physics that deals with the behaviour of subatomic particles such as photons and electrons — to encrypt information.
One such method, known as quantum key distribution, stores encryption keys inside the properties of subatomic particles. In Dr Ling’s case, it is in the polarisation states of photons, or single particles of light.
Quantum key distribution has considerable advantages over conventional encryption systems.
Because of the random nature of quantum signals, no amount of computing power can predict their outcomes; the technology is thus considered to be unhackable and immune to computing attacks.
In addition, because the properties of quantum particles change the instant we measure them, quantum keys are also considered to be tamper-proof.
“If an eavesdropper tried to tamper with the machine, they wouldn’t actually know what they were doing, because you can’t actually know a photon’s state until you finally measure it,” explained Dr Ling.
Rules of entanglement
In practice, quantum key distribution can be implemented through a number of different techniques.
Dr Ling’s work focuses on one such technique — quantum entanglement, a phenomenon in which photons establish a connection that allows them to act as a single entity, regardless of how far apart they are.
To generate quantum entanglement in the laboratory, specialised equipment is used to split photons from a laser beam into pairs of very strongly correlated, or entangled, lower energy photons. These can then be used to carry out quantum key distribution.
If a photon is created with its polarisation in a particular direction — up, for example — then its entangled twin is also always pointing up, no matter how far apart the photons are.
Thus, after the polarisation states of a sequence of entangled photons are measured, parties linked by a quantum key distribution should both carry a sequence of perfectly correlated random numbers.
If this correlation is broken, it is a clear indication that security has been compromised, said Dr Ling.
“Entanglement is very powerful. If an eavesdropper is interfering with the system—taking photons and sampling them, for example — it destroys the quality of the entanglement state,” he explained.
Once this happens, errors are introduced.
By calculating the error rate, scientists can then make a decision about whether the quantum key is secure, or whether it has been compromised and should be regenerated.
To go big, first go small
A further advantage of quantum key distribution is that it can be used at larger geographical scales.
“We can transmit photons through optical fibres; we can send them through telescopes and between buildings or moving platforms,” said Dr Ling.
“This exchange of particles can also be used to exchange information between parties that are very far apart.”
This means that data centres on different continents, for example, could exchange information securely using quantum keys, as long as they are connected by an optical fibre link.
Dr Ling hopes that in the future, quantum key distribution will be able to span the globe. For now, however, transmitting photons via optic fibre still results in signal losses.
“We can secure an area the size of Singapore very well, but if you want to transmit signals between Singapore and any other city, it’s a bit of a challenge,” he said.
To make field testing outside of the laboratory easier, Dr Ling’s group at CQT is developing miniaturised quantum entanglement generators that are compact enough to be handheld.
To help the technology go truly global, one of his goals is to be able to put these devices into orbit, on CubeSats or other classes of small satellites.
“If we can combine satellite and fibre optic technology, we’re talking about providing the world with very secure ways of encrypting data,” he said.