Cryptography is a little understood system though highly relevant to all of our lives. It is the art of writing or solving codes. In other words, it is the means to encode communication in a secret way so that only those that have the ‘key’ can unlock and read it. It has been around for millennia with rulers passing on messages in code so that no one else could read it. Even to this day it has become a virtual presence online and involve a highly security oriented system intent on ensuring our privacy.
One of the earliest forms of cryptography was Julius Ceasar’s substitution cipher to convey messages to his generals during war. What he did was substitute each letter in his original message by shifting it by three letters down the alphabet, e.g. ‘a’ was substituted by ‘d’, ‘b’ by ‘e’ and so on. Fast forward to World War 2 and the Germans had created the enigma machine because messages via radio could be listened in on by the Allied forces. The machine encrypted a message based on settings that were changed every day. Only another enigma machine calibrated to the exact same settings could unravel the message.
Today, a modern form of public key encryption is used to keep our online communication safe from prying eyes. Emails are used by everyone these days but instead of having one key like those above, it has two. There is a public and a private key. The private key is held by one individual, let’s say ‘A’ and the public key can be owned by anyone, in this case ‘B’. The public key can unlock the message when its locked by a private key and vice versa. When A sends a message, they lock it with their private key and B can unlock it. When B replies and locks it with their key only A can unlock it with their private key. The public key, being able to unlock the private key means that the receiver can confirm the message was only locked with the private key or by A. This means that only A and no one else could have put the message in the email. We call this the digital signature.
Although this is a simplistic version of encryption, there are many forms used throughout all of our systems and applications we use every day. Passwords for one are another common form of encryption to access emails and databases. Encryption is a daily part of our lives…