The Renaissance era became the dawn not only of science and art, but also of cryptography. Some ciphers of this period for a cryptographer are like the Sistine Chapel or Mona Lisa for a connoisseur of painting. At the same time, it was during the Renaissance that encryption turned from a magical abracadabra and a way to put dust in the reader's eyes into a full-fledged working tool for protecting valuable information.

This article is mainly about the historical context, information on some ciphers is given in a dose. After all, cryptography does not exist in isolation from historical realities, its development is inextricably linked with people's needs and time.

From magic to practice

European cryptography took the first timid steps from occultism and religion to practical application in the Middle Ages.

In the 13th century, the English thinker Roger Bacon created his work "The Monk's Message on the Mysteries of Art and Nature and the Insignificance of Magic", where he called on scientists to encrypt their works and first described methods of information protection. However, it was only the first swallow to the formation of cryptography as an independent discipline in this historical period. And the only benefit of encryption, according to the author, was to fence scientific knowledge from the "common people". Alas, the "Dark Ages" did not differ in humanism.

In the Renaissance era, peasants and townspeople also did not scrite encrypted messages. But politicians, diplomats and the military have not been without cryptography in their "games of thrones" since the 15th century.

Another cryptographic feature of the Renaissance is the abundance of highly specialized scientific and methodological treatises on ciphers and methods of their use. Thus, cryptography has turned into a full-fledged orderly field of knowledge. At the same time, simple monoalphabetic ciphers (for example, the "Caesar cipher") were replaced by polyalphabetic replacement codes that are more resistant to frequency cryptanalysis.

The encryptors, who clung to outdated methods, eventually lost and turned out to be, to put it simply, "mammoths". Talented cryptanalysts began to click their encryptions like nuts. Polyalphabetic systems were improved throughout the 16th century, culminating in the famous "Vigener cipher". However, first things first.

Cryptography at the service of politics and diplomacy

Immortal works of Renaissance art are just the tip of the cultural and historical iceberg. While Titian and Leonardo gave birth to their masterpieces, Europe was the formation of full-fledged states and nations in the modern sense, pan-European and world markets developed, international logistics was established, and finally, diplomatic services of a new model appeared.

As the historian of cryptography David Kahn noted, in the Renaissance "diplomacy fed cryptography". Medieval knightly sneechings like "I'm coming to you!" went into the past and were replaced by ingenious sneaky games in which secure correspondence played a key role.

The diplomatic and cryptographic boom affected not only Western Europe: it is enough to recall the Embassy Order with the Cypheric Hut established in Moscow in the middle of the 16th century, the encryptions of the ambassadors of Tsar Fyodor Ioannovich, Patriarch Filaret with his Cypher Alphabet mentioned by Karamzin.

However, Italy, France and England reached the greatest heights in political and embassy intrigues, as well as the use of ciphers.

Italian Cryptographic Renaissance

Italy is the soul and the very embodiment of the Renaissance. It is logical that it became the cradle of cryptographic revival. In addition, Italy consisted of independent city-states that fought for a place under the sun: they weaved intrigues, united in alliances, sought military assistance from foreign countries. In such an environment, ambassadors inevitably turned into "honorable spies".

And what a spy can do without cryptography?

How did it all begin?

The Vatican was a pioneer in the encryption of diplomatic documents. The papal archives contain a document of 1326, where the names of people and the names of the opposing groups Guelphs and Ghibellines are hidden. The first are a kind of elves who support the limitation of the power of the Holy Roman Emperor in Italy and adherents of the Pope. The latter, on the contrary, supported the emperor. Guelphs are designated in the document as "children of Israel", and Ghibellines as "Egyptians": such a simple "Easter egg" from the biblical Book of Exodus. The authors tried to hide the support of a particular group in case the document falls into the wrong hands. In addition, some words in the papal documentation were disguised by separate letters: A - king, D - pope, etc.

The oldest cryptographic keys in the West were also created for the office of the pontiff, more precisely, the antipope Clement VII. In 1378, he fled to Avignon and declared himself the rightful owner of the papal throne. It is significant that among the first orders of the self-proclaimed pontiff was the creation of new ciphers. Antipope Secretary Gabrieli Lavinde developed individual keys for all 24 correspondents of Clement VII.

Lavinde keys combine fragments of code and cipher. All 24 keys contain replacement cipher alphabets with pacifiers, as well as lists of popular words or names hidden by two-letter codes. In fact, this is the first cipher nomenclator known to researchers.

Cryptographic race

Venice was not inferior to the papal throne, and at first it was completely ahead of it in encryption and cryptanalysis. The city of channels became the birthplace of the world's first state security service, which was responsible for the protection and decoding of correspondence from the 15th to the 18th century. The mysterious "Council of Ten" (Consiglio di Dieci) trained cryptographers and even took a "graduation exam" on encryption from them.

This Venetian "Big Brother" was cruelly punished for violations of "information security": athe disclosure of the encryption key was considered treason and entailed the death penalty.

Even at first glance, harmless educational treatises on cryptography were kept in the strictest secrecy. Thus, the Venetian writer Agostino Amadi and his Trattato delle Cifre, which described most of the ciphers known in the second half of the 15th century, became public only in the middle of the 19th century. It is still unclear who was the customer of this 700-page "Talmud" and how it was used. They've just classified it!

The first outstanding European cryptanalyst named Giovanni Soro was also Venetian. In 1506, he was appointed Secretary of the Ciphers of the Venetian Republic. The enumeration of states whose ciphers were hacked by Soro alone will be drawn to a separate article in terms of volume. It got to the point that since the beginning of the 16th century, the Pope himself appealed to the Venetian for the deciphering of intercepted messages, which were not up to the teeth of the Vatican cryptographers.

The sources describe the case when the depe of the pontiff Clementius VII (no, this is not the anti-pope with the same name mentioned above) went to his opponents. Exclaimed: "Soro can open any cipher!", the pope sent a copy of the message to the Venetian "maestro" to check the resistance of the cipher. The cryptoanalyst could not read the encryption, and dad breathed a sigh of relief. It's hard to say whether this was really the case, or whether we are facing an unverified gossip, which is rich in narrative sources. In any case, such stories are not born out of thin air.

In 1542, Soro headed a small cryptographic department of three people, including himself. Perhaps the unit served as a prototype of those very Black Cabinets.

Soro's team worked in a secluded corner of the Venetian Doge's Palace, in a room "without windows and doors" and in an atmosphere of the strictest secrecy. When another intercepted depech was received, the poor were forbidden to leave their secret office until the cryptogram was fully deciphered. In the breaks between such crunches, Soro and his subordinates laid out solitaire and described the methods of their work in the treatises. In short, the rest of crypto analysts only dreamed of, and when they managed to snatch at least a few hours to sleep.

Now we will return to the Vatican, which was not going to yield to Venice in this "cryptanalysis race" and even more so depend on the services of foreign cryptographers. In 1555, the position of secretary for ciphers was also established in the papal curia. Two years later, the crypto analysts of the pontiff left no stone unturned from the cipher of the Spanish King Philip II. Some papal cryptographers did not even need to know the language in which the message is written. Thus, in 1567, the vicar of St. Peter's Cathedral in Rome unraveled an intercepted Ottoman cryptogram. But he "didn't know four words" in Turkish.

Cryptoanalysis also flourished in Florence, where the Count of Sasset Pirro Musephilli especially distinguished himself in this field. In the middle of the 16th century, he unraveled the nomenclators of King Genich II of France and read many encrypted dispatches. Like Soro, Musephilli became a world star and received orders from European rulers. Once the King of England turned to him for a transcript of an intercepted French message hidden in the sweeps of gold shoes.

Even Renaissance stegano containers were real works of art.

French Cryptographic Renaissance

Unlike fragmented Italy, the country of royal lilies was a powerful centralized state. But there were enough diplomatic and political "scandals, intrigues, investigations" there as well. First, France constantly fought against strong opponents - Spain and England. Secondly, the internal situation in the country often heated up to the limit, and the throne wobbled under the monarchs because of the threat of coups. Politicians and ambassadors had to constantly encrypt themselves and intercept other people's coded depeches.

French "machine" for cryptanalysis

Among the French masters of Renaissance cryptanalysis is the first Secretary of State and court decoder under Francis I Philibert Baba. A contemporary described it as a tireless machine for killing the transcription of messages. Moreover, Babu solved cryptoframes even in Spanish, Italian and German, which he did not know, and without an alphabet at hand.

"He worked hard on the message day and night for three weeks before solving one word," the eyewitness writes. "After the gap was made, the rest happened very quickly and resembled the destruction of the walls."

As is often the case with workaholics, work from the dawn to the dawn harmed the personal life of a crypto analyst, who was awarded for his work not only by the castle of Bourdesier near Tours, but also... by horns. Babu's beautiful wife was the mistress of Francis I himself and regularly visited the royal chambs, while her faithful was sathering over another transcript for the benefit of the crown.

How the author of the theorem saved the king

Another honored French Renaissance cryptographer is François Viet.

First of all, Viet was a lawyer and a member of the Privy Council under King Henry IV, while mathematics and cryptanalysis were his hobbies. However, it was thanks to his enthusiasm that the adviser helped the king to stand up in the fight against the so-called Holy League. This was a Catholic faction led by the Duke of Mayenne, which was not rested by the Protestant on the throne.

Having obtained military and financial support from another ardent Catholic, King Philip II of Spain, the Holy League took control of Paris and a number of other key cities in France. Henry found himself in the position of "the cast is removed, the client is leaving!". But, fortunately for the king, his agents intercepted part of Philip II's correspondence with his military commanders. Of course, the messages were encrypted.

Here the author of the immortal theorem showed himself in all his glory. Since 1588, he had deciphered a number of Spanish dispatches, which spoke of the movement and plans of the troops of the Holy League. Valuable operational data allowed Henry to act in advance and defeat the superior forces of the Duke of Mayenne in the battle on the River Ivry on March 14, 1590. However, the subsequent siege of Paris ended in failure for the king. Although Henry could not put checkmate on his opponents, a loud victory in the general battle helped him keep the throne.

Witchcraft cryptanalysis

Viet was so confident in his talents that sometimes he himself forgot about caution. The day after the battle of Ivry, the cryptoanalyst sent Henry an open transcript of the intercepted message of the Spanish military commander Moreo to Madrid. The depecha contained details of Moreo's negotiations with the Duke of Mayenne and was protected by a newly developed Nomenclator cipher developed by the Spaniards. Viet not only did not bother to defend the transcript himself, but also bragged about his violation of "information security".

"Don't worry that for your enemies this will be a reason to change their ciphers and disguise themselves even more," Viet boasted. "They have repeatedly changed them, and yet their tricks have been and will always be revealed."

When the Spaniards intercepted this letter, Philip II was enraged: his next "impregnable" cipher turned out to be a sleft for Viet. Unable to resist the cursed Frenchman in a cryptographic duel, the Spanish king decided to literally give him the heat to send him to the bonfire.

Philip informed the Pope that Viet allegedly opened the papal ciphers with the help of witchcraft and should appear before the cardinals' court. In theory, the trick could have worked, because the cryptanalyst remained a Catholic, despite his service to the Protestant monarch. But the pontiff did not buy it, because he knew perfectly well about the unreliability of Spanish ciphers and immediately guessed what was going on. Philip outsmarted himself and found himself, to put it mildly, in an awkward position. Spanish cryptographers were also ashamed of the whole world.

This historical sitcom episode vividly demonstrates the confrontation between old-fashioned cryptographers and progressive cryptoanalysts like Babu and Viet. Eventually, the "contrugation" turned into the "beating of babies", although the good old nomenclators remained in use until the 20th century.

Subsequently, France conquered and retained the palm of the championship in encryption for a long time: it is not for nothing that the first "Black Cabinets" state units for perlustration and decoding messages appeared there in the XVII century.

English Cryptographic Renaissance

Shakespeare's homeland also experienced a cryptographic boom in the Renaissance era. Moreover, it was in England at that time the most resonant and dramatic case related to encryption occurred. But let's not run ahead.

How the ambassador's carelessness spurred the development of encryption

Until the 16th century, the British looked at the protection of information through their fingers. For example, Thomas Spinelli, the British ambassador to Madrid, has never changed the cipher for thirteen years when sending letters with valuable intelligence from Spain to the foggy albion. It is not surprising that in the end this code became known to the Spaniards and was not printed in newspapers or, as they were then called, volatile leaves. Most protected messages combined encrypted text and ordinary words, so it was not difficult to hack them even without a key at hand.

For example, here is an excerpt from a letter from the Spanish ambassador Rodrigo Gundisalvi de Puebla to the father-in-law of the English King Henry VIII Ferdinand of Spain, where the cipher and open text are adjacent:

The payment of the doory is postponed until the feast of the Archangel of St. Michael [September 29]. Regarding CCCCXXIII (marriage) DCCCLXXVIII (Queen of Castile) CCCCLXXXVIII (c) DCCCLXXXVII (King of England), King Henry would like to be informed when King Ferdinand returns to Castile to DCCCCLXXXIII (send) DCCCCLXXVIIII (embassy).

- London, April 15, 1507. MMCCXXXI (de Puebla).

During the reign of Henry VIII in England, it was decided that it was time to change something. Cryptography was put on wide state tracks, and each ambassador's letter from abroad began to be protected with a new unique cipher to exclude compromise.

Code of the divorced queen

To paraphrase Shakespeare's lines, "there is no sadder story in the world than a story about a rejected woman". We are talking about the first wife of Henry VIII, Catherine of Aragon, who turned from a beloved wife and a strong monarch into an exile. For 24 years of marriage, she could not give birth to a male heir, and the king decided to divorce her. The Catholic Church did not bless the divorce, which eventually resulted in Henry's conflict with the Pope and the creation of a Protestant Anglican denomination in England.

As they say, kings can do anything.

Catherine of Aragon did not accept her husband's decision and tried to protest the divorce in the papal court in London in 1529, but was defeated. Anyway, until the end of her days she considered herself Henry's only legitimate wife and the true queen of England, which she carefully signaled to her Catholic supporters in the hope of help. It is known that since 1532, already in exile, Catherine wore a precious pendant with "harmless" inscriptions. As it turned out, it was a cipher. Recently, it was hacked using the Wordle riddle method. The transcript reads: "Henry the King (Henricvs Rex) and Catherine".

Political will for cryptanalysis

The further development of the English cryptographic school is largely due to the political will of the Minister and Chief of Intelligence Elizabeth I, Sir Francis Walsingham. He first became interested in encryption when he read the work of Italian mathematician and cryptographer Girolamo Cardano, the inventor of the famous encryption grid.

Theory is a theory, but the minister decided to create a full-fledged cryptographic service only after seeing the fruits of encryption in practice. In 1577, the letters of King Philip of Spain, intercepted in the Netherlands and deciphered by the Flemish crypto analyst Van Marnyx, were on the Wolsingham table. The latter persuaded his half-brother and the same convinced Catholic Juan of Austria, who ruled a large part of the Dutch lands, to attack Protestant England together. The surprise did not work out: the British began to hastily prepare for the defense, and the Spaniards had to abandon their adventure.

Assessing the practical benefits of cryptography, Walsingham founded a encryption school in London and invited a certain Thomas Fellipes to serve. This inconspicuous and "insignificant in all respects" functionary was fluent in Latin, German, French and Spanish, and at the same time skillfully broke any ciphers. It was his cryptographic work that put an end to the sensational trial of the unfortunate Scottish and, for a short time, French Queen Mary Stuart.

The case of Mary Stewart, or "How cryptanalysis decided the fate of the queen"

In short, in 1585, Mary Stuart, expelled from Scotland by the will of fate, found herself in English captivity because of her enmity with the Protestant Queen Elizabeth and her commitment to Catholicism.

The prisoner was constantly transported from the estate to the estate. Of course, she did not sit "behind bars in a damp dungeon": at first she was even allowed horseback riding in parks and trips to the healing waters in Buxton. But over time, this "sanatorium" was covered, and the conditions of detention of the honorary prisoner were tightened.

Elizabeth took the trouble to cut off all of Maria's contacts with the outside world, and, as it turned out, not without basis.

In England, supporters of Mary Stuart were immediately found from among the noble Catholics dissatisfied with the Protestant queen. Moreover, the prisoner's grandmother was Margaret Tudor, the older sister of Henry VIII himself. This was enough to justify Maria's claims to the English throne, whether something happened to the current queen (an accident on the hunt or an "accidental" tenfold fall on a knife).

The leader of the conspiracy was the nobleman Anthony Babington. He corresponded with the prisoner, miraculously bypassing the "seven seals" behind which she was.

All messages from both sides were encrypted. Maria's letters were encrypted by her personal secretary Gilbert Curley.

Maria Stewart and the conspirators used a simple monoalphabet substitution cipher or, in other words, the same nomenclator. It was a system of 23 signs to denote English letters, except for the letters j, v and w. To increase the durability of encryptions and complicate cryptanalysis, another 35 characters masked individual words and phrases. The cipher also included four dummy signs. Finally, the symbol σ indicated a subsequent "double letter" (doubled letter).

Another good-willed person of Mary, the English Catholic Gilbert Gefort organized the transmission of messages. The cunning Jifort managed to bypass the guards of Chartley Hall Castle, where the prisoner was, with the help of... beer.

Gilbert used "beer steganography": a bribed local brewer hid messages in hollowed-out plugs in barrels with a foamy drink. When the cargo entered the castle, Maria's servants sneaked out the letters and brought them to their mistress.

The answers were transmitted in a similar way when the brewer took away empty barrels. So, here is another example of a Renaissance steganocontainer not as elegant as French gilded shoes, but practical and effective.

In July 1586, another encrypted letter from Babington was delivered to Chartley Hall, who asked to bless the murder of the queen and shared the details of his plan. Six young nobles were supposed to stab Elizabeth I in her own palace. On July 17, the prisoner sent an answer and gave the go-ahead for a coup.

But the light at the end of the tunnel went out before it really concelled. The master of "beer steganography" Jifort turned out to be a double agent and conveyed all the messages to Walsingham - and so it begs "What's a twist!". Maria's fatal answer first fell into the hands of the above-mentioned court cryptanalyst Thomas Felippes. He deciphered the message with one left hand, then copied the original and attributed a short encrypted postscript in the prisoner's handwriting with a request to Babington to name all the conspirators. They say, so Maria will be able to better orient herselly in what is happening and will know who to trust.

Babington would surely have handed over all his comrades with guts in a reply letter, blindly hoping for the durability of the cipher and not feeling the trick. But fate decreed otherwise, although the outcome was the same. The day after receiving a fake response from Mary Stuart, the head of the conspirators himself went to the Walsingham office to apply for a passport to travel abroad to his Catholic allies. What was the surprise and embarrassment of the officials when the chief investigator of the country personally came to visit them. The secretary of the department, Skademor, still pulled himself together and summoned the soldiers who arrested Babington. The nobleman did not have time to answer the prisoner and reveal his accomplices, but it was not necessary - torture did its job. Soon all the other conspirators were caught and imprisoned in the Tower.

Seven troublemakers were brutally executed on September 20, 1586. Maria Stewart's secretary was properly interrogated, and he handed over his mistress. In October, Maria was taken to Fotheringay Castle and put on trial. Still, the prisoner was of royal blood, so it was necessary to obey external decency and justify her execution in the eyes of the public.

The defendant denied her involvement in the conspiracy to the last, but the intercepted and deciphered letters became reinforced concrete evidence against her. On February 1, 1587, Elizabeth signed a decree on the execution of Mary, and 7 days later she was beheaded. This tragic story was another confirmation of the importance of cryptanalysis, which determined the fate of the crowned person.

At the end of the Renaissance, encryption and cryptanalysis became so indispensable that the courts of most European monarchs had their own cipher secretaries.

They developed new codes, encrypted messages and solved intercepted depeches in full-time mode.

Such functionaries served as a transitional step in the era of the "Black Cabinets".

In the next article, will talk in more detail directly about cryptography: key figures, works and methods of encryption of the Renaissance.