Encryption refers to converting data into a different form so that it cannot be understood by anyone except the intended recipient.
The information is fed through an algorithm, which scrambles the basic text to a form that is indecipherable. The recipient also possesses the algorithm, often called the encryption key, and hence can decrypt the information to a readable form.
The thing that makes encryption work is that while an eavesdropper may be able to intercept a communication, they will only be able to access gibberish without the key.
The concept has taken on new importance in the digital age, in which cryptographers use these techniques to secure computer systems and digital communications. This includes both stored data and data travelling across communication channels.
The term comes from the Ancient Greek ‘Kryptos’, meaning secret. The related term cryptography refers to the science of secret codes whereas encryption is an actual cryptographic process.
Encryption in history
Julius Caesar gave his name to one of the earliest known cyphers, the Caesar cypher. This is a fairly simple encryption technique which shifts every letter in the alphabet by a certain number of places in the alphabet. For example, if the number one was used as the key, B stands in for A, C stands in for B, et cetera.
Encryption contributed significantly to the early development of computing during World War Two. While the British were able to intercept German armed forces’ communications, the Germans used a machine called Enigma to scramble them, meaning they had no use.
Mathematician Alan Turing devised a primitive computer that was able to decrypt the communications once the key was discovered. The events were dramatised in the 2014 film The Imitation Game, starring Benedict Cumberbatch.