Taken from :
Juan Jesus Velasco
Although we think of Alan Turing, Claude Shannon or the NSA as references in the field of cryptography (and, of course, they are), this art goes back much further back in time. Message encryption has been practiced for more than 4,000 years and, precisely, the origin of the word cryptography is found in the Greek: krypto, "hidden", and graphos, "write"; that is, hidden writing.
A communication is encrypted when only sender and receiver are able to extract the information from the message; Therefore, any person outside the communication will only be able to see a gibberish without meaning and the content of the message will be totally hidden.
Although the hieroglyphs of Ancient Egypt did not have a military intention, they are usually taken as one of the first examples of "hidden writing" in history (the Rosetta Stone was needed to decipher them). There are "non-standard hieroglyphs" that, according to experts, were intended to provide more dramatic drama to the history that was represented; These inclusions sought to provide the story described with greater mystery or intrigue and "complicated" the reading with the inclusion of unusual symbols (although the practice would be abandoned over time).
The Bible (specifically in the book of Jeremiah) makes references to the Atbash, a system of substitution of letters that was used to encrypt messages and that goes back to the year 600 BC; examples of encryption of substitution messages were also found in the Mahajanapadas kingdoms of India.
If we look at Ancient Greece, in Homer's "Iliad" we can find a reference to the use of message encryption. Bellerophon, mythological hero, delivers to King Iobates of Lycia, a letter encrypted by King Preto of Tirinto; The content of the letter is secret and is encrypted but the message hides that the bearer of the letter, Bellerophon, must be killed.
Spartans also used cryptography to protect their messages; specifically, a technique known as transposition encryption that consisted of rolling a parchment over a stake (called Scythe) that was used to sort the letters and display the message. In order to decipher it, the receiver had to have a scythe of the same diameter as the one used by the sender (symmetric cryptography) because it was the only way to visualize the message in the same way.
From ancient Rome comes the so-called César encryption, which, as its name indicates, its use is attributed to Julio César himself. This encryption is based on the displacement of letters and, therefore, each letter of the original text is replaced by another letter that is a fixed number of positions later in the alphabet. According to the writings of the Roman historian Suetonius, Julius Caesar used a 3-letter scroll and Augustus, first emperor and nephew-grandson of Julius Caesar, used a scroll of a letter.
During the Middle Ages, the great crypto revolution had its origin in the Arab world. In the ninth century, Al-Kindi would lay one of the fundamental bases for "breaking encrypted messages" thanks to the study of the Koran; Frequency analysis (a technique that was used during World War II) was based on analyzing patterns in encrypted messages to locate repetitions and find the correlation with the probability that certain letters appear in a text written in a specific language. Ibn al-Durayhim and Ahmad al-Qalqashandi also delved into frequency analyzes and worked on the development of more robust codes by applying multiple substitutions to each letter of a message (thus breaking the patterns that could cause a code to break).
At the time of the Renaissance, the Papal States would be characterized by an intensive use of cryptography; in fact, one of the key figures of the time in this discipline was Leon Battista Alberti, personal secretary of three Popes. Alberti, like Ibn al-Durayhim and Ahmad al-Qalqashandi, would work on polyalphabetic encryption and develop a mechanical (disk-based) coding system known as Alberti encryption. Although it has not yet been deciphered and remains a mystery, in the Renaissance it has its origin that remains the "great challenge" of code breakers: the Voynich Manuscript, a book whose content is still unintelligible and whose code is not It has been able to break.
Following the Renaissance, another key figure in the cryptography of this period was the German monk Johannes Trithemius who published in 1518 a complete treatise on steanography and coding called "Polygraphia." In the 16th century, France would see the birth of another of the key figures in cryptography, Blaise de Vigenere, who in his work "Traicté des Chiffres" gave the codes posed by Trithemius robustness.
Cryptography until World War II
With the passage of time, cryptography became a key piece within armies around the world. During the Wars of religion of France (which faced the State with the Huguenots), "deciphering the enemy messages" became a tactical objective and Antoine Rossignol would become, in 1628, one of the most important cryptographers in France and, of In fact, both his son and his grandson worked at the first cryptology center in France (known as "Cabinet Noir"). During the 18th century, cryptography was present in the majority of armed conflicts that developed in the world and, precisely, would have a key role in the "War of Independence" of the British colonies in America by intercepting the messages of the British Army and also when new encryption methods are developed (such as Thomas Jefferson's encryption wheel).
In the Crimean War, the United Kingdom got an important advantage thanks to the mathematician Charles Babbage (pioneer in the field of computing thanks to the development of the Analytical Machine). Babbage worked on deciphering Vigenère codes that were considered extremely robust and, evidently, this work provided an important advantage to the United Kingdom (to the point of classifying Babbage's work as secret and attributed to Friedrich Kasiski because it came to it conclusion years later).
The most important treatise on cryptography of this era was made by Auguste Kerckhoffs, a Dutch-born linguist and cryptographer who published in the Journal of Military Sciences of France in 1883 a treaty that completely renewed the base of cryptographic systems with its 6 principles basic that a cryptographic system had to meet.
During World War I, cryptography was used intensively. Germany developed the Ubchi code that was disarmed by France and the naval codes of Germany were deciphered by the "Room 40" of the United Kingdom Admiralty, which allowed them to get ahead of Germany and prepare for battles like the one in Jutland.
Cryptography in World War II
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 submarine fleet, and its communications were indecipherable thanks to the Enigma machine. In addition to the traditional fronts and the battles between the armed forces a new battlefield had been opened: breaking enemy communications; a task that the Allies entrusted to a group of mathematicians, engineers and physicists who worked from the facilities of Bletchley Park and among which was Alan Turing.
Perhaps the work of Alan Turing and the Allies is the best known work on cryptography during World War II; However, he was not alone. The encryption of the communications marked the conflict and a very varied set of techniques was used to prevent the enemy from intercepting the communications. The United States, for example, rescued a technique that it had already used successfully during World War I and, instead of resorting to complex encryption algorithms, opted to use the Native American languages as a code.
The United States Marine Corps had among its ranks half a thousand Native Americans who served as radio operators and encrypted, in their native language, the messages to be transmitted so that the Japanese army could not understand anything that was transmitted. Navajos, Meskwakis or Comanches were some of the Native American nations that were part of the ranks of the United States armed forces in operations in Africa, Europe (including the Normandy Landings) and the Pacific. Although the American command opted for Native Americans to perform these tasks, it is worth knowing, at least as a curiosity, that Basque was also used experimentally to encrypt messages on the Pacific front (in Guadalcanal and the Solomon Islands ).
Also in the area of the Pacific front, the effort to break the encryption keys used by Japan was key to stop its progress. Thanks to the joint effort of the United States and forces of the Netherlands and Great Britain, it was possible to break the Japanese naval code JN-25 and, in this way, to know the battle plans of Japan in Midway.
Modern cryptography and the digital age
After World War II, cryptography made a great leap thanks to Claude Shannon, known as the father of communication theory. In 1948, Shannon, who worked at Bell Laboratories, published "A Communications Theory of Secrecy Systems"; a fundamental article in which coding techniques were modernized to transform them into advanced mathematical processes. While it is true that frequency analysis was based on statistics, Shannon mathematically demonstrated this fact and introduced the concept of "uniqueness distance" that marked the length of an encrypted text that is needed to be able to decipher it.
The explosion of computing, and its development after the Second World War, made computers a key instrument in the encryption and decryption of messages; therefore, for security, most countries considered cryptography as something secret and linked to intelligence and espionage tasks. From the mid-50s to the mid-70s,the NSA monopolized and blocked any type of publication or study on cryptography in the United States; the information that was accessible to the public was obsolete and to work in the field of cryptography, basically, the only option was the NSA (more than one research project in the field of the University was "closed" by this Agency and books like "The Codebreakers" by David Kahn had to go through the NSA censorship filter before being published). The United States was not the only country to devote resources and means to cryptography, the United Kingdom founded in the 60s the "Communications-Electronics Security Group" (CESG) within the Government Communications Headquarters (GCHQ).
Until March 17, 1975 the first "public advance" (not dependent on the NSA) linked to the world of cryptography would not arrive. IBM developed the Data Encryption Standard (DES) encryption algorithm that, two years later, would become a Federal Information Processing Standard (FIPS 46-3) and would extend its use worldwide. In 2001, DES would transfer its position to Advanced Encryption Standard (AES) which, after 5 years of revision, became a standard.
The second of the great public advances also had its origin in the 70s. Virtually all the systems we have talked about are symmetrical; Both sender and receiver must handle the same code and be mutually informed of the code they will use when exchanging information. However, Whitfield Diffie and Martin Hellman laid the foundations of asymmetric cryptography (public key and private key) in the article "New Directions in Cryptography" published in 1976. Asymmetric cryptography today is essential for transactions made through the Internet, by For example, on pages that use the HTTPS protocol or to encrypt our messages using PGP (which combines both symmetric and asymmetric cryptography).
As we have seen, cryptography has played a relevant role in the history of mankind and its importance has been increasing as the volume of information we have been generating or exchanging has increased. Edward Snowden's revelations about PRISM and the rest of the Internet spying programs of the NSA have made us think about cryptography but, in reality, it has always been present and that's when we make a phone call with our mobile device, we use Telegram or we make a purchase online.
Translation done through third-party program.