China uses a quantum satellite to transmit potentially unhackable data

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 encryption.

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.