China’s quantum satellite can be hacked, a former Russia-based quantum researcher who is now working in Singapore has warned.

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https://www.scmp.com/news/china/sci...can-be-hacked-singapore-based-scientist-warns

China’s quantum satellite could potentially be hacked due to tiny delays between its onboard lasers that could be exploited by eavesdroppers in an attack, a former Russia-based quantum researcher who is now working in Singapore has warned.
The tiny delays could provide “ample opportunities” to hack Micius, the world’s first quantum satellite, whose performance is key to expanding China’s quantum communication network.

Quantum communication is a form of information transfer that relies on quantum physics-based cryptography to encode data in single light particles called photons.

Quantum key distribution (QKD) is one method that relies on exchanging secret keys between two parties used to decrypt the information, which makes it difficult for eavesdroppers to listen in and is theoretically unhackable.

“However, it is widely known that realistic QKD devices can be vulnerable to various types of side-channel attacks that rely on flaws in experimental implementation,” said quantum researcher Alexander Miller in a non-peer-reviewed paper submitted online on May 10.

After analysing data obtained during communication between a ground station and Micius, Miller found time delays between the lasers on the quantum transmitter on board, which showed that the “distribution of quantum keys from Micius was insecure”.

The paper was published as a preprint on the open-access repository arXiv, meaning it has not undergone peer review.

Miller is currently affiliated with the National University of Singapore’s Department of Physics, according to the paper.

His online research profile states that he was previously affiliated with the Moscow-based quantum company QSpace Technologies – who are mentioned in the paper as the provider of data used in the analysis – and the Moscow Centre for Quantum Technologies.

The South China Morning Post reached out to the National University of Singapore, which did not respond.

QSpace Technologies, which declined to comment on the content of the paper, said it was not aware of the article before its publication and had not received an official request for data from the author, adding that it was grateful to Chinese colleagues for the opportunity to conduct a joint experiment with the satellite.

Micius, also known as Mozi, was launched in 2016 as the first quantum satellite in orbit. It relies on the decoy-state BB84 protocol, which is one of the most widely implemented quantum key distribution schemes.

In the BB84 protocol, before the sender – Alice – sends a series of ones and zeroes encoded in photons to the receiver – Bob – she sets their orientation.

When Bob receives them, he guesses which basis or tool he should use to measure the photons, after which Alice and Bob share the tools they used to measure the direction for each photon over a public channel, but do not share whether it was a 0 or 1. If they used the same tool, they would keep the photons and establish a secret key.