First Ever Quantum-Encrypted Conference Call Completed

Concept art of quantum keys being transferred between a research station and the satellite Micius. Photo: Johannes Handsteiner/The Austrian Academy of Sciences (OeAW)

As research and quantum computing advances, more and more possible applications for the technology are coming to light. Quantum cryptography can be used to help people ensure that transmissions between them and other parties are confidential, thanks to the way elementary particles behave, and the quantum internet could serve as a specialized and secure portion of the regular internet. Over the past weekend, a new application for quantum-based technologies presented itself, courtesy of a demonstration of the first ever secure video conference call encrypted by quantum technology.

A Landmark Conference Call

A team of scientists from China and Austria completed the first ever quantum-encrypted teleconferencing call, connecting from Vienna to Beijing over a secure connection which is said to be unhackable. The call was made by Chunli Bai, President of the Chinese Academy of Sciences to President of the Austrian Academy of Sciences, Anton Zeilinger, and the Rector of the University of Vienna, Heinz W. Engl. The call was a live experiment in using quantum encryption, done in front of various representatives of the media and scientists.

The call was the fruitful result of a long period of research initiated back in 2013. The research project, called QUESS (Quantum Experiments at Space Scale), utilizes a Chinese satellite to do quantum communication experiments between the satellite and the Earth. Scientists from the Chinese Academy of Science, as well the Austrian Academy of Sciences and the University of Vienna all worked on the project.

President of the Austrian Academy of Sciences, Anton Zeilinger (center). Photo: The Austrian Academy of Sciences (OeAW)

The successful demonstration showed that orbital quantum technology is a viable option for global communication in the future. Quantum technologies offer a major advantage over traditional communication technologies because hacking them is theoretically impossible due to the immutable laws of physics.

Says Zeilinger:

The exchange of quantum encrypted information over inter-continental distances confirms the potential of quantum communication technologies as opened up by fundamental research. This is a very important step towards a world-wide and secure quantum internet.

Quantum communication technologies are distinct from regular communication technologies because they are much more complex, and thus much more secure. In traditional communication systems, packets of data are sent one way during the transmission, then sent back the other. If that transmission is intercepted by somebody, they could easily discern what data is being sent. However, quantum communication methods make use of a phenomenon called quantum entanglement to provide security.

Quantum Entanglement and Security

An animation depicting quantum entanglement. Photo: National Institute of Standards and Technology

Quantum entanglement is one of those “spooky” phenomena in quantum physics, referring to a situation where a particle has a “twin” of sorts, and no matter what distance separates these two particles they mirror each other. Whatever happens to one particle will instantly impact the other particle in the same way. They can’t be described as independent of each other, even when they are separated by massive distance. Physicists are still struggling to understand the exact how’s and why’s of quantum entanglement, but fully explaining the phenomenon isn’t necessary in order to leverage it.

What’s important is that the particles are entangled with each other, so their state can only be discerned as a union, not as the individual segments. When they’re employed in communication networks only the parties who are at one end of the conversation or the other can discern what is being transmitted, making an interception in the middle basically impossible, at least without being detected.

To make use of the quantum communication system a quantum key had to be generated for the call between the two parties. The Chinese satellite Micius generated particles of light that had random directions of oscillation, the polarization of photons. These photons and their random polarizations were transmitted as a binary signal to a reception station in Austria. The reception station then compared the sequences with the polarization states of the photons.

If somebody had attempted to intercept the polarized photons during the transmission between the satellite and the ground reception station, the quantum state of the photons would be changed due to this interaction, leaving a telltale signature that would expose any hacker. Theoretically, anyone trying to measure the polarization of these photons would immediately be discovered, and the parties warned. If however there is no change in the data which is logged at both the receiver and transmitter, then the sender and receiver have successfully generated a quantum key.

Two quantum keys, one held by the ground station and one held by the Micius satellite were combined in orbit and then transferred back to the ground research stations located in China and Austria. The researchers then used the combined key as well as their own separate key to generate a code for the decryption and encryption of the information exchanged in the call.

Hacking and Quantum Computers

Quantum security measures are likely to be an important and necessary invention in the following decades as if quantum computers become a reality, some researchers are warning that they could effectively render all existing internet security protocols irrelevant. Researchers like Tanja Lange at the Eindhoven University of Technology, and Daniel J. Bernstein from University of Illinois, Chicago have warned that computers could break open ECC and RSA cryptographic systems.  These technologies are amongst the most secure systems existing today, yet a quantum computer could penetrate their defenses in days or even hours.

According to Lange, securities agencies and the NSA are pressuring researchers to develop solutions to this problem, accompanying a recent surge in interest in post-quantum cryptography. This is because even today’s data may not be safe, as an attacker could theoretically hack records of communications today, and then break their encryption protocols with a quantum computer years down the line.  Lange makes it clear we must further invest in the development of quantum security techniques.

“Bringing cryptographic techniques to the end user takes often another 15 to 20 years, after development and standardization,” says Lange.

It is also important to recognize that quantum communications are only unhackable at the moment and that new developments and technologies could compromise even their current level of security. One day, quantum security systems may prove hackable after all. One of the enduring lessons of cybersecurity is that there is a constant struggle between security methods and those looking to subvert them and that those who develop security systems should not be overconfident in the safety of their systems.

In the meantime, more tests of the quantum safe communications technology are planned to take place between China, Italy, Singapore, Germany, and Russia. If these tests go well, the research team hopes to have a European-Asian quantum-security communications network operational by the end of the decade.

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