The simple writing of a message that most people could not read is considered to be the earliest form or cryptography. The word cryptography is comes from two Greek words, “kryptos” which means hidden and “graphien” which means writing.
Early cryptography was mainly focused on converting messages into unreadable figures in order to protect it during the time it was being carried from one place to another.
Nowadays, cryptography has evolved from the basic message privacy to message integrity checking, digital signatures and sender/receiver authentication amongst other things.
People have been concealing messages from the time they moved from caves and started living in civilized society. Since that time, the idea of cryptography has been taken seriously.
Historians believe that the earliest forms of cryptography were found in the cradle of civilization. This includes the regions surrounded by Egypt, Greece, and Rome.
As early as 1900 B.C., Egyptian scribes concealed messages using hieroglyphs. For the Greeks, they hid their messages by wrapping a tape around a stick and then writing the message on the wound tape.
The trick in this method was that the message would be meaningless if the tape was unwound. To decipher the message, the receiver would be required to wrap the tape around a stick of the same diameter. The Romans used the Caesar Shift Cipher method to encrypt their messages.
In this method, the sender and the receiver agreed on a number and used it to shift letters, thus writing a message using the letter-shift. To decrypt the message, the receiver would be required to shift the letters back using the same number.
A good example of the Monoalphabetic Cipher is the Caesar Shift Cipher. This encryption method was very easy to break as a person was only required to write down the alphabet and then juxtapositioning the start of the alphabet to every succeeding letter.
The person would see if the message was readable after every iteration. As for the Greeks, once the stick method was known, it was just a matter of using sticks of various diameters until the message became readable.
The art and science of cryptography did not show any major advancement until the Middle Ages. At that time, cryptography was used by most governments in Western Europe in one way or another. It was majorly used to communicate with ambassadors.
Leon Battista Alberti, also known as The Father of Western Cryptology is well known for the polyalphabetic substitution which he developed. In this method, two copper disks which fit to each other were used. Each copper disk had the alphabet inscribed on it.
The disks were rotated after every few words so as to change the encryption logic. This limited the use of frequency analysis to crack the cipher. This method went through a lot of changes, and most of these changes are attributed to Vigenere.
However, this method was finally cracked after being in use for a long period. In 1918, Gilbert Vernam created the Vernam-Vigenere cipher with the aim of strengthening the broken cipher. This led to the development of the one-time pad, which used a keyword only once. It proved to be near unbreakable.
In modern times, the public key has been the most common method of cryptography. This method is a form of asymmetric encryption. In this method, the sender uses the private key to encrypt the message, and the targeted receiver uses the public key to decipher the message. In this way, the receiver can know the origin of the message.
This method constitutes the backbone of the Digital Signature. The challenge in this method is when several organizations require the use multiple public keys; being able to know which key to use and when to use it. It doesn’t matter the method used in encryption; you will always get the best results if you apply a combination of several methods, one after the other.