Education

Intro to Cryptosystems

Cryptanalysis

The Zimmermann Telegram

Edgar Allan Poe

Home Education Contact Us Shop CryptoStick Gallery Contests

History of Cryptography

Cryptography has been around a long time with the earliest known examples dating clear back to about 1900BC. Ancient Egyptians encoded hieroglyphic writings, and the ancient Hebrews used a method where each letter was replaced with a letter the same distance from the end of the alphabet, A=Z, B=Y, etc., using an Atbash Cipher. A very early tablet from Babylon includes an encrypted method of making a glaze for pottery, an industrial process. Clearly, even from the very start, cryptography was not only used to protect the official secrets of the government, but was a part of everyday life in both business and personal communication.
As time went on more and more cultures were finding situations where cryptography was a necessary part of the transaction. Most of these early cipher methods used the standard alphabet of the culture, replacing one letter with another. The message to be encoded is called plaintext, and the encoded version of the message is called ciphertext.One substitution rule is called shift transformation, and an early version of this in practice, is credited to Julius Caesar. It is now referred to as the Caesar Cipher. Using a predefined rule, each letter of the alphabet is replaced by another letter in the alphabet by shifting a uniform amount to the right. The first documented use of this substitution cipher was by the Roman army during the Gallic Wars. Today we call any cipher using a simple letter shift a Caesar Cipher.
Instead of shifting you can get even more security by shuffling the letters of the alphabet. This is called a mixed monoalphabetic substitution cipher. The twenty-six letters of the standard alphabet used in our culture could be used to make as many as four-thousand one-hundred four possible keys, and was thought secure for a long time. Variations of this method were used in government, the military, and by private citizens for many centuries into the Middle Ages.
The method of breaking a code using frequency analysis was discovered by Arabic scientists. The earliest known description of this is in a manuscript by Abu al-Kindi on deciphering cryptographic messages published in the ninth century. This method of codebreaking involves an analysis or study of the ciphertext, counting the number of times each letter is used. If we know that the most commonly used letter in English is E, we can assume the most common letter in the ciphertext is also E. Working through the alphabet based on the normal frequency of use for each letter can then often reveal the hidden plaintext.Due to the fact that ciphers and codes kept getting broken, more complicated ciphers were created with multiple replacement symbols for each letter, for common words, nulls or spaces. A similar cipher was used during the imprisonment of Mary Queen of Scots to communicate with conspirators to plan the assassination of Queen Elizabeth I. Ultimately the messages were intercepted and the code broken, leading to the execution of all the plotters.
One of the strongest ciphers developed at that time was the Great Cipher of Louis XIV, in seventieth century France. It was used for the King's most secret messages and plots, including interactions with the Man in the Iron Mask. After the King's death it was lost, and was not broken for over two centuries, finally being cracked by Commandant Etienne Bazeries.

To ease the tediousness of encrypting and decrypting by hand, mechanical devices were developed. Most of these took the form of ciphers based upon wheels or cylinders. When in the post of Secretary of State, Thomas Jefferson developed one of these mechanisms, now called the Jefferson Cipher Cylinder, and used it to encrypt diplomatic messages. During the American War Between the States, both sides used encrypted messages, and all spies and officers in the Army of the Confederacy were supplied with the Confederate Cipher Wheel for this purpose. During the world wars, all sides used cryptography machines, the most famous of which were the Swedish Hagelin Machine, the Japanese Purple Machine, and the German Enigma Machine

The most widely used encryption tool to date is the Data Encryption Standard (DES). DES has protected information ranging from national security data to bank accounts and electronic funds transfers. The cipher was originally introduced by Chaude Shannon, a pioneer of the information theory, in the 1940s. DES used multiple transpositions and substitutions. A similar system was adapted by IBM in the 1970s, and formulized into a standard algorithm called Lucifer. Both of these ciphers are now considered less secure since methods of breaking them have been found, and a new cipher is under development as a replacement.
There are many other ciphers than just those discussed here, and other parts of the whole world of cryptography are just as fascinating. We hope you will take a while to visit the other parts of this website, and see just what we mean.