A scientist works on a quantum computing project at a research facility in China. Source: CCTV / YouTube screen grab

China says it has become the second country to develop an “unhackable” communications technology that uses the emerging science of quantum cryptography to protect sensitive data.

The Chinese Academy of Sciences conducted the first quantum  videoconference call late last year together with the Austria Academy of Sciences in Vienna, using a secure line with data channeled through China’s quantum-science satellite Micius. Xinhua newsagency hailed the experiment as a “tour de force”.

Data encryption based on quantum computing, or quantum mechanics, was pioneered by the Los Alamos National Laboratory in the US, which announced in 2014 it had created a secure network. Germany, Japan, Australia, Sweden and other countries are working on similar projects.

Traditional cryptographic systems use the factors of a number that is  itself the product of two very large prime numbers to encode signals, on the premise that it would take too much time, and too much computer processing power, for an algorithm to factor their product.

Quantum computing takes a more minimalist approach by limiting a data communication to just two parties, the sender and a receiver. Entangled photons, or visible light particles, are sent to the two stations encoded with specific polarizations (the direction of the light wave’s wobble) as a security layer. 

The laws of quantum mechanics make it physically impossible for the (transmission) to be intercepted and read without eavesdropping being detectable

The satellite creates security keys using measurements of the polarizations, which the stations can use to encrypt and decrypt the data. It is technically “unhackable”, as users can quickly detect the presence of a third party: anyone eavesdropping would be unable to look at the photons without changing or even destroying them.

“The laws of quantum mechanics make it physically impossible for the (transmission) to be intercepted and read without eavesdropping being detectable by the sender and receiver,” an expert told the Beijing-based tabloid Global Times.

Such a secure system for transmitting encrypted voice calls, faxes and emails containing classified information would be of immense value for the top brass of the People’s Liberation Army and intelligence networks at a time when cyber warfare has taken on greater importance.

However, some Western analysts believe the technology will be broken, as it has its own inherent weaknesses. One is a reliance on lasers, which are often tuned to such a low intensity that they can accidentally duplicate photons; the first would be encoded, but not the second one.

It can also be difficult to detect when a single photon has arrived, making users think the system has been hacked when it hasn’t been.

Another problem is that fibre optic channel losses (broken signals), which could be due to scattering, reflections, dust or other factors,   limit the distance of such communications to just a few hundred kilometres. Chinese scientists and military engineers have overcome this hurdle by transmitting through the Micius satellite.

Named after Mozi, a prominent philosopher during the Warring States period of 475–221 BC, Micius was launched in August 2016 and is said to be the world’s first quantum satellite. Its initial task was to test quantum key distribution.

The Micius satellite blasts off from Jiuquan on August 16, 2016. Photo: AFP

Lead scientist Pan Jianwei of the University of Science and Technology of China, an institute in Hefei, Anhui that is closely affiliated with the PLA, developed a secure relay through Micius and then created a secret key connecting Beijing and Vienna, 7,600 kilometres apart, in what was lauded as a giant step toward a global space-based quantum internet.

“This is something that will really awe the world after wider military and commercial application,” a member of Pan’s team told Xinhua.

However, Pan did caution that the technology was in its very early stages. The capability demonstrated by Micius is “sufficient for the very early stages of a quantum internet, similar to the state of cell phones in the 1970s,” he said.

The city of Jinan, capital of northern Shandong province, will become the hub of these quantum communications. A regional network is already operating for the use of local government, as well as the nearby headquarters of the PLA’s Northern Theatre Command Ground Force.

The city also straddles the 2,000 km Beijing-Shanghai quantum line, which was inaugurated in September.

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