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The Latest in Cryptology
October 1, 2017

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The Latest in Cryptology

Chinese researchers have teleported information into space using the laws of quantum physics, thereby ushering in an important chapter in cryptology.

China has just taken a quantum leap ahead of the rest of the world in providing secure communication. At a time when most of our communication travels across the internet, securing information from the wrong eyes is paramount. Until this past spring, it was also nearly impossible. That changed when Chinese researchers teleported information into space using a form of physics called quantum entanglement, thereby ushering in an important chapter in cryptology.

Until now, safeguarding data was done using codes or mathematical ciphers. Encryption based on a code relies on a code book to provide the meaning of a message. For example, the Morse code book denotes the relationship of alphabetic characters with dots and dashes. Securing a message in this way really means keeping the code book out of the wrong hands.

A mathematical cipher is an expression referred to as an algorithm or a key. Julius Caesar was known to apply a simple cipher to hide the meaning of messages that had military significance. He would shift characters to the right by three, so that the letter A would be replaced by a D and so on. Today’s ciphers are more complex and rely on one key to encrypt the message and a different key to decrypt it.

The fundamental problem with codes and today’s math-based ciphers is that given enough computational power, they are breakable by a third party.

Chinese researchers have left ciphers behind and turned to science. They based their encryption on the elementary laws of quantum entanglement to ensure the confidentiality of information transmitted. In so doing, they have successfully piloted the fundamental application of quantum cryptography.

Not to get too technical, physics at an atomic (a.k.a. tiny) scale is governed by different laws than those that apply to the world around us. One of these laws is that you cannot measure the speed and location of elementary particles (the fundamental building blocks of matter, antimatter and force particles). Anyone trying to measure a particle’s speed destroys the information of its location and vice versa. This doesn’t mean an observer’s technology is inferior — it means no one can measure this quantum state. If you want to impress your engineer friends, this law is known as the Heisenberg uncertainty principle.

Then there’s quantum entanglement. Entangled particles share a unique connection, so whatever is happening with one is also happening to the other. This means that if you have access to one particle, you can correctly infer what’s happening to its companion, just as seeing a coin lying heads-up allows you to deduce that the tail side is facing down.

Chinese researchers used a satellite, Micius, to beam one entangled particle (in this case a particle of light called a photon) to one location and the second entangled photon to a location 1,200 kilometres away. They used the entangled photon as their key for encryption/decryption. Any attempt by a third party to steal one of the keys (that is, measure either the photon’s location or speed) destroyed the connection and any ability for them to correctly decrypt it.

Teleportation is the term used for sending quantum state information over a long distance. The vacuum of empty space minimizes photon loss and is a key step in developing a global-scale quantum internet. That’s why a satellite was used.

What does this mean? Cryptography now has icon-clad keys based on the laws of quantum physics that prevent the keys from being intercepted and used by unintended third parties. We now have keys that no amount of computational power can break.

We are still a few years away from a truly secure internet based on the unbreakable laws of quantum mechanics, but this accomplishment demonstrates an essential step in that direction.

This post was originally published in CPA Magazine