A brief history of encrypted communications and cryptography

With the idea of better ​​understanding what cryptography is and how this discipline has evolved until today, let's take a look back in time to learn about the history of cryptography and information encryption.

The origins of cryptography

Though we may think of Claude Shannon, Alan Turing, or the NSA as references in the field of cryptography -and indeed they are-, this art goes much further back in time. Message encryption has been practiced for over 4,000 years and precisely the origin of the word cryptography comes from the Greek “krypto”, (hidden), and “graphos” (writing), that is, hidden writing.

A communication is encrypted only the when transmitter and the receiver are able to extract the information of the message; therefore anyone outside the communication will only be able to see gibberish and the content of the message will be completely hidden.

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Although the hieroglyphs of ancient Egypt had no military intention, they are usually seen as one of the first examples of “hidden writing” in history, as the Rosetta Stone was needed to decode them. There are non-standard hieroglyphs which, according to experts, aimed to bring more drama to the story being represented. These inclusions seeked to provide greater mystery or intrigue to the story that was being described, and they would make the reading more complicated with the inclusion of unusual symbols although the practice be abandoned over time.

The Spartans also used cryptography to protect their messages; specifically, a technique known as transposition cipher which consists of a parchment scroll on a stick -called scytale- that served to sort the letters and display the message. To decrypt the message, the receiver needed to have a scytale the same diameter as the one used by the transmitter. This is known as symmetric cryptography because it was the only way to view the message as originally intended.

From Ancient Rome comes the encryption method known as Caesar cipher which, as its name suggests, its use is attributed to Julius Caesar himself. This encryption is based on the movement of letters and, therefore, each letter of the original text is replaced by another letter that is at a fixed number of positions later in the alphabet. According to the writings of the Roman historian Suetonius, Julius Caesar used a shift of three letters and Augustus, first emperor and grand-nephew of Julius Caesar, used a shift of just one letter.

Centuries later, during the Renaissance, one of the key figures of cryptography of this period was the German monk Johannes Trithemius, who published in 1518 a complete treatise on steganography and coding called “Polygraphia”. In the sixteenth century, in France, another of the key figures of cryptography was born: Blaise de Vigenère, whose work “Traicté des Chiffres” provided robustness to the codes that Trithemius proposed.

Modern times: Cryptography in the World Wars

During World War I, cryptography was intensively used. Germany developed the Ubchi code that decrypted by France, and Germany’s naval codes were deciphered by the UK, which allowed them to get ahead of Germany and prepare for battles such as the Jutland one.

Cryptography was key during World War II and, in fact, changed the course of the war. Germany had managed to dominate the North Atlantic with its fleet of submarines, and communications were indecipherable thanks to the Enigma machine. In addition to traditional fronts and battles between the armed forces, a new battlefield had appeared: to decode enemy communications; a task that the allies commissioned to a group of mathematicians, engineers and physicists, such as Alan Turing, who worked from the Bletchley Park facilities.

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Perhaps the work of Alan Turing and the allies is the best known one on cryptography during the World War II; however it was not the only one. Encryption of communications marked the conflict and a varied set of techniques was used to prevent the enemy from intercepting communications. The United States, for example, reused a technique that had already successfully been used during World War I and, instead of resorting to complex encryption algorithms, they opted to use the languages ​​of Native Americans as a code.

The United States’ Marine Corps had among its ranks five hundred Native Americans who served as radio operators and they would encrypt, in their native language, messages to keep the Japanese army from understanding anything that was transmitted. Navajos and comanches were some of the native groups that were part of the ranks of the armed forces of the United States in operations in Africa, Europe and the Pacific.

Also in the Pacific front, the effort to break the encryption keys used by Japan was key to stopping their advances. Through joint efforts of the US and forces of the Netherlands and Britain, the Japanese naval code JN -25 was deciphered and, in this way, Japan’s battle plans could be known.

As we have seen, cryptography has played an important role in the history of mankind and its importance has increased, and so has the volume of information that has been generated or exchanged. The revelations of Edward Snowden about PRISM and other spyware online have made us think about cryptography, but in reality, it has always been present and it is there when we make a phone call with our mobile phone, when we use Telegram or perform an online purchase.