A brief history of Cryptography

Since humanity could write or at least transmit messages, there has been a desire to hide them from prying eyes. In the following article, we will briefly examine the history of cryptography.

What is now Signal or Discord in the virtual space was in the old days of cryptography. In many cases, of course, we are not imagining some cursive but rather some other code system that is supposed to be known only to the recipients of confidential messages.

And the importance of the word "in principle" is shown by the fact that cryptography - or the breaking of it - could even change the course of history. During the First World War, for example, British cypher-breakers managed to crack a telegram from German Foreign Minister Zimmermann to the Mexican president, which led to the United States entering the war.

Perhaps an even more famous example is Enigma. For a long time before the Second World War, the relatively complex device, which used rotating mixing discs, enabled efficient encryption. When it was secretly cracked, it caused heavy losses to the German army. On the other hand, the Americans trained Navajo Indians as radio operators, who transmitted messages in their native tongue, interspersed with code words, and did so very efficiently.

What is cryptography?

Cryptography is an entire discipline known collectively as cryptography. Before the 19th century, it was considered part of linguistics, but today it is more correctly thought of as an interdisciplinary discipline, closer to mathematics and computer science. In fact, within it, it can be classified as an interface between number theory, algebra, computation theory and probability theory.

Its name comes from the ancient Greek words kryptós (hidden) and gráphein (writing). It is a discipline that has developed enormously over the last millennia, especially in the previous few decades.

Cryptography requires plain text and an encryption process (i.e. an algorithm) that creates the cypher text. If both texts are considered a sequence of numbers, then the cypher algorithm is a mathematical function. Although there is a cypher text that can, in principle, be read by anyone, for example, in Latin characters, its meaning can only be understood by someone with the key to retrieve it, also known as decrypting.

Cryptography in antiquity

The first cryptographs date back at least two and a half millennia to around the sixth century BC, when Hebrew scholars used monoalphabetic cyphers. A monoalphabetic cypher means that the same substitution is used throughout the text.

For example, the process called atbas was used in the Bible for a single phrase. This is an effortless procedure from today's point of view, whereby the first letter of the alphabet is replaced by the last, the second by the letter before the last, and so on.

The next episode is known from around 400 BC, thanks to Herodotus. He recorded that Hystiaeus, allied against the Persian king, shaved the hair of a messenger and then wrote the message on his head. When the messenger's hair had grown, he crossed the border safely and delivered the message to another tyrant, Aristagoras. This story may not be accurate, but it illustrates how varied cryptography can be.

It would be strange if the Romans did not use some cypher. The idea of the so-called Caesar code is quite simple: each letter in the alphabet is replaced by a letter at a certain distance from it. Julius Caesar used these cyphers to communicate with his generals, and it later became one of the most widely used methods of cypher writing.

According to Nándor Várkonyi, the runic letters used by the Vikings - which appeared around 150 AD - were once all signs or images, but "today we can hardly, if at all, unravel the magical connections that determined the order of the images. What is certain, however, is that the signs had a secret meaning: they were 'sacred', not only among the Egyptians, who called them sacred signs, sacred inscriptions (hieroglyphics) but also among other peoples. More precisely, they also had a secret, esoteric meaning known only to the initiated. It was a sacred, secret science, practised for a long time only by priests, and its knowledge was the same as the knowledge of divine doctrines. Anyone could learn to read and write, but initiation was not easily dispensed," writes Várkonyi in The History of Writing and the Book.

Cryptography in the Middle Ages  

Várkonyi also writes about the Székely-Hungarian runic script, which our ancestors knew and used even before they arrived in the Carpathian Basin. The signs were mainly carved on wood or sticks, less often scratched, painted on walls or written on paper. The right-to-left, shorthand, angular-shaped system of symbols was used effectively for coding. "As the scribes of the early Middle Ages mainly used Latin and the new script had not yet been adapted to the characteristics of the Hungarian language, runic writing survived for 2,000 years in the lower strata of society (at least among shepherds) and as a cypher."

In the Middle Ages, almost all peoples developed some form of cypher. Arab scholars used monoalphabetic substitution as a basis for frequency analysis, while around 1466, the Italian humanist polyhistor Leon Battista Alberti created the first polyalphabetic cypher.

The latter involves changing groups of letters and using different substitutions in different text parts. Polyalphabetic cyphers are no longer used today, but this method makes it more challenging to decipher codes by frequency analysis, and it became the basis for cypher scripts used in the following centuries, such as the Vigenère cypher, and even for well-known machines such as the Enigma used during the Second World War.

Scientists of every century have contributed to the history of secret codes, from the Morse Code of 1837 to such well-known devices as the German Enigma, the Japanese Purple and the world's first programmable electronic computer, the British Colossus.

Computer-aided quantum cryptography will likely make inroads in the future, but that does not mean that handwriting cannot be used to create unbreakable code. Sometime between 1450 and 1520, for example, the so-called Voynich manuscript, named after an American bookseller, was built. The book was written in an unknown alphabet and language, and its contents still need to be deciphered.

The latter sentence is also true of the manuscript volume known as the Rohonci Codex, which was transferred from the library of Gustáv Batthyány to the Hungarian Academy of Sciences. The eponymous small town in western Hungary is now part of Burgenland. In conclusion, we encourage everyone to experiment with these secret signs - even if it's a game; who knows, maybe the unbreakable code of the next century will be created with an Etelburg pen.

Key sources:

Nándor Várkonyi. Széphalom Könyvműhely, Budapest, 2001.

Wikipedia, The history of cryptography (Hungarian)

Wikipedia, Vigenère cipher (Hungarian)