Quantum Cryptology

Some independent research from one of our RGS Physics pupils:

Quantum cryptology is a form of encrypting data or communications using the laws of quantum mechanics. Unlike forms of encryption that rely on the laws of maths, which no matter how complicated the encryption, given a powerful enough computer can be broken, quantum cryptology relies on the laws of physics which are vastly more difficult to crack and claimed by physicists to be unbreakable. Therefore many now view this as the new holy grail of encryption.

Older forms of encryption used very big prime numbers as their keys which created very complicated maths puzzles but with advanced enough computers these problems could have taken a matter of hours to crack. With the use of quantum encryption this is no longer possible because instead of using a prime number the encryption key is sent as a string of photons and due to Heisenberg’s uncertainty principle anyone attempting to eavesdrop on the  communication would not be able to examine the photons to gain knowledge of the key without changing or destroying them. There is often an example used with the characters Alice and Bob communicating and Eve trying to observe their communications. Therefore if Eve is observing the communication Alice and Bob will be aware of it as there will be a discrepancy when they compare the keys as Alice will know what filter the Bob is using to measure the photons and the effect it will have on each of the photons she sends, and will therefore be expecting a certain result. However when the Eve changed the photons by observing them she changed the result the Bob would get meaning when Alice and bob compare keys they know someone has interfered with their communications.

The reason photons can be used to send communications is because they spin and certain photons will have certain spins when passing through certain filters, this allows for some spins to be denoted as 1s and others 0s.


This method allows for 100% secure communication because the photons that are not affected by Eve form Alice and Bob’s secure key that only they know, however no form of encrypted communication is 100% due to the potential for human error.

By Ollie Edwards

And if you want to know a little more about quantum physics I found this video amusing and informative





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