China uses a quantum satellite to transmit potentially unhackable data
Arjun Kharpal   | @ArjunKharpal
5 Hours Ago

China has demonstrated a world first by sending data over long distances using 
satellites which is potentially unhackable, laying the basis for next 
generation encryption based on so-called "quantum cryptography.

Last August, China launched a quantum satellite into space, a move which was 
called a "notable advance" by the Pentagon.

Using this satellite, Chinese researchers at the Quantum Experiments at Space 
Scale (QUESS) project, were able to transmit secret messages from space to 
Earth at a further distance than ever before.

The technology is called quantum key distribution (QKD). Typical encryption 
relies on traditional mathematics and while for now it is more or less adequate 
and safe from hacking, the development of quantum computing threatens that. 
Quantum computing refers to a new era of faster and more powerful computers, 
and the theory goes that they would be able to break current levels of 

That's why China is looking to use quantum cryptography for encryption. QKD 
works by using photons — the particles which transmit light — to transfer data.

"QKD allows two distant users, who do not share a long secret key initially, to 
produce a common, random string of secret bits, called a secret key," the 
researchers explained in a paper published in the journal Nature on Wednesday.

"Using the one-time pad encryption this key is proven to be secure … to encrypt 
(and decrypt) a message, which can then be transmitted over a standard 
communication channel."

State news agency Xinhua called the encryption "unbreakable" and that's mainly 
because of the way data is carried via the photon. A photon cannot be perfectly 
copied and any attempt to measure it will disturb it. This means that a person 
trying to intercept the data will leave a trace.

"Any eavesdropper on the quantum channel attempting to gain information of the 
key will inevitably introduce disturbance to the system, and can be detected by 
the communicating users," the researchers said.

The implications could be huge for cybersecurity, making businesses safer, but 
also making it more difficult for governments to hack into communication.

China successfully sent the data over a distance of 1,200 kilometers from space 
to Earth, which is up to 20 orders of magnitudes more efficient than that 
expected using an optical fiber of the same length, the researchers claimed. 
It's also further than the current limits of a few hundred kilometers.

"That, for instance, can meet the demand of making an absolute safe phone call 
or transmitting a large amount of bank data," Pan Jianwei, lead scientist of 
QUESS, told Xinhua.

The Chinese government has made the development of the space sector a key 
priority. For example, it has laid out plans to get to Mars by 2020 and become 
a major space power by 2030.

And China has global ambitions for its QKD. It sees its satellite system 
interacting with ground-based QKD networks to create a global secure network.

"We can thus envision a space-ground integrated quantum network, enabling 
quantum cryptography — most likely the first commercial application of quantum 
information — useful at a global scale," the researchers said.
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