Secret communication – a coded history

The year 2003. The world woke up with a new perspective on history, a revelation that would shock many and create avid interest in the art of secret communication. Dan Brown’s Da Vinci Code created a furore among critics and readers alike. While the former chose to point out the literary inconsistencies, the latter rushed to read up more on the hidden layers of Da Vinci’s art – in other words, their first ever tryst with cryptography. However, this science of secret communication has been as old as mankind itself. Well, almost.


Since the dawn of time mankind has been developing secret codes. This chapter follows this evolution

The year 2003. The world woke up with a new perspective on history, a revelation that would shock many and create avid interest in the art of secret communication. Dan Brown’s Da Vinci Code created a furore among critics and readers alike. While the former chose to point out the literary inconsistencies, the latter rushed to read up more on the hidden layers of Da Vinci’s art – in other words, their first ever tryst with cryptography. However, this science of secret communication has been as old as mankind itself. Well, almost.

Starting simple

Early evidence of cryptography indicates that it has been around since Biblical times. The Bible Code, also known as the Torah Code, is supposedly a series of secret messages embedded in the text of the Torah. This has been decoded using ELS (Equidistance Letter Sequence) and is a highly debatable topic.

It is believed that cryptography began approximately around 2000 B.C. in Egypt. The famous hieroglyphics adorning the tombs of rulers depicted the lives of the kings and the great acts done by them. Intentionally kept in a cryptic mode, these hieroglyphics were only used for an ornamental purpose rather than for secrecy. Soon, this system became obsolete.

Storing Intelligence

Since cryptography is mysterious in its approach, this science began to be associated with the dark arts. And since most early cryptographers were usually the intelligentsia or the scientists, commoners considered them to be the devil’s followers. In the Middle Ages, many writers, who were also members of secret political or religious organizations, found an innovative way to communicate through codes. They published books which contained ciphers.

Some say secret codes and symbolism exit in DaVinci’s paintings

This led to a trend of secret writing and every royal court across Europe competed to encrypt ciphers that couldn’t be broken. During this period, many intellectuals chose to hide their scientific inventions and discoveries in secret code for the fear of being excommunicated by the Church. However, these mavericks trusted the future generations to unveil their discoveries, understand the implications and appreciate their efforts.

Masonic symbols

Early ciphers

The earliest and most commonly used cipher was the Atbash cipher, which emerged from Mesopotamia. Sharing many similarities with its Egyptian counterpart, cuneiform script was used to decode the message. Used in Babylon and Assyria, the Atbash cipher substitutes the last letter of each alphabet by the first, as seen below:



The earliest cipher dealt with symbolism and is a key to an immense source of ancient wisdom, both scientific as well as philosophical. Early philosophers chose to subtly encode their message in verbose literature, intentionally meant to be heavy-worded. These ciphers were concealed artfully, either in a watermark, or through a repeated sequence appearing in a particular order. Under the guise of subtlety, many a carefully hidden message made its way to the recipient it was intended for.

Freemasons and their secrets

The highly controversial organization of Freemasons has brought to light the many uses of ciphers. While mostly misunderstood, Freemasons were essentially a group of highly intellectual individuals, chiefly believing in science. Their immense store of scientific knowledge was kept hidden through complex symbols and ciphers, sometimes even for years. Usually, these symbols were imbibed from nature with a deep reverence, which only those initiated into the ways of the organization could comprehend. It was during the middle ages that ciphers became increasingly popular. Governments used them to communicate with their ambassadors in other countries, and it was not only the Western nations which had begun to understand the importance of having an unbreakable code.

Eastern codes

The Ancient Chinese utilised the pictorial (ideographs, to be precise) form of their language to enclose the deeper meanings attached to the words. Most often, messages would be conveyed in ideographs to maintain secrecy. However, such use of cryptography is not apparent in any of China’s earlier military conquests.

History claims that most ciphers in India were highly advanced, with the Government employing complicated codes to communicate with their spies distributed across the length and breadth of the country. However, one of the first credible advances in this field was devised in Italy. An exhaustive organization was set up in Venice in 1452 to deal with cryptography. This ensured that all ciphers were solved and segregated for the Government’s discretion.

All In Greek

The Greeks are believed to have been well acquainted with the use of ciphers, which were right before the eyes but seldom noticed. The Greek historian Herodotus revealed instances of secret messages hidden beneath the wax on wooden tablets and also of situations where discrete information was tattooed on a slave’s head and covered by regrown hair. Those were perhaps the crudest forms of steganography, a form of cryptography. Steganography is a form of security through obscurity, or in simple terms, secrets hidden in plain sight. It not just conceals the message but also protects the persons communicating it.

First mention of cryptography in iliad

Snatches of cryptography are believed to have been used in the popular Greek epic, the Iliad, especially when Bellerophon was presented before the king with a secret tablet. This tablet informed the king that Bellerophon must be executed. The king tried doing so by having him fight many mythical creatures. But to his chagrin, Bellerophon won every battle.

A caesar cipher

Binary Inspirations

Spartans employed a method called the Skytale (or Scytale) cipher, where a thin sheet of papyrus was wrapped around a staff. Then, the messages were written down all along the staff. The papyrus was then unwrapped. To decode and read the message, the papyrus would need to be wrapped around a staff of an equal diameter. Greek warriors used this technique to communicate. At that time, it was quite effective as only the right staff would yield the message. The Spartan military was believed to have used the Scytale transposition cipher extensively.

Yet another Greek discovered an ingenious cipher. Polybius used a cipher where the letters of the alphabets were arranged in a five-by-five square (the Polybius Square). The letters “I” and “J” occupy the same square. It’s identical to the Playfair technique. The rows and columns are numbered 1 to 5, so every letter has a pair (either in a row or a column). The pairs can now be easily communicated by torches or hand signals. The Polybius Square came into being since it reduced the size of the symbol set. In a way, the Polybius Square can be considered as one of the earliest predecessors to the modern day binary codes.

When In Rome

While the Greeks used cryptography for their military purposes, the Romans were not to be left behind. Julius Caesar discovered a unique way to communicate secretly. The Caesar Cipher has a letter shifted two places further in the alphabetical order. T shifts to V and Y moves over to A, to give an idea. Given below is the Caesar’s code which was perhaps the first ever cipher to be used by children.

“You decoded my cipher? Et tu Brutus?”



This is an example of a mono-alphabetic substitution cipher where each alphabet is assigned to another. However, it was Leon Battista Alberti who laid the cornerstone to most modern cryptography. Also known as the Father of Western Cryptography, he is credited with the invention of the polyalphabetic substitution, also known as the Alberti cipher, which came about before Caesar’s cipher.


This technique enables different ciphertext symbols to portray the same plaintext symbol. A closer inspection reveals that this simple substitution makes it all the more difficult to interpret the code, especially using the method of frequency analysis.


Ingeniously, Alberti designed this cipher after decoding others and understanding their vulnerabilities. This unique cipher was designed with two copper disks, fitting into each other. The disks have alphabets inscribed on them. A coded message can be sent by aligning a prearranged letter on the inner disk with the corresponding alphabet on the outer disk, which makes up the first character of the ciphertext. A few words later, the disks are rotated and the new alignment of the letters will create a totally new cipher. By doing this, the effectiveness of frequency analysis becomes limited and the cipher emerges as a strong one.

King Ferdinand VII


Despite other limitations, the constant rotation of these disks would change the cipher countless times, within the message. At that time, this was a pioneering concept in cryptography.

German influence

Trithemius, a German monk, gave cryptography a major boost way back in 1518. Interestingly, his deep interest in all things occult drew him to the realm of secret communication. He authored six books on ‘Polygraphia’ and created a polyalphabetic cipher. It was a table consisting of repeated alphabets in each row, with a duplicate sequence above it having a letter shifted in the arrangement. The message can be coded when the first alphabet of the plaintext is substituted with the first row, the second letter from the second row and so on.

English messages

The prevalence of cryptography in old England has been traced to the philosopher Roger Bacon and the poet Geoffrey Chaucer. During the reign of Henry VII, cryptography was used by supporters of Perkin Warbeck, who was the Duke of York and the younger son of Edward IV. Warbeck was a renowned figure in the English court. However, his attempts at annexing Cornwall failed and resulted in his execution.

Amidst the entire furore, a substitution cipher for Warbeck has been documented. The prosecution record of indictment of the Earl of Warbeck recorded that while in prison, Warbeck delivered to one of his supporters a book called “ABC”, also called a “Crosse Rowe”. Each letter in the book had a corresponding sign written by Warbeck. This was to ensure that using this cipher, the supporter could write back a message which would

not be understood by those who didn’t know the code.

Diplomatic ciphers

Catherine of Aragon was believed to have learnt the art of cryptography and used to write in ciphers. This helped her play a vital role as a secret channel between King Ferdinand of Spain and King Henry VII of England. After King Henry VII’s death and her subsequent marriage to King Henry VIII, Catherine still didn’t relinquish her cipher to the ministers but handled the cipher for secret communication between the kings. In 1515, Catherine gave up her position as an ambassador when her worthy successor arrived from Spain.

King Charles 1628 AD

Despite their advancements in other sectors, England remained largely hostile to the use of cryptography. Only near the end of Henry VII’s reign were ciphers used by the English court. However, ciphers were used by the Spanish ambassador, in the course of exploring diplomatic ties with England. While the King of England chose to send his written plain text messages via sea, to protect their contents, King Ferdinand of Spain chose to communicate sensitive matters through ciphers with the help of Catherine.

Later on, ciphers were largely employed by English ambassadors to Spain to keep the government abreast of the situation in the host country. Ambassadors John Stile and Thomas Spinelly used ciphers to communicate with King Henry VIII.


A matter of code

After discovering the convenience and security which a coded message provided, most English kings began to write in cipher. Charles I was the monarch who made the most use of ciphers during his reign. During their separation, Charles I and Queen Henrietta Maria used complicated ciphers to correspond.

Charles I used many different ciphers during the period of 1640 to 1650 to communicate sensitive information. His recipients included Prince Rupert, the Parliament General and ministers in Oxford.

Marie Antoinette

French connection

The highly controversial Queen of France and Navarre, Marie Antoinette relied on ciphers to communicate with Count Axel von Fersen after their flight to Varennes. At the height of the French Revolution in 1791, King Louis XVI and Queen Marie Antoinette escaped France in disguise. But they were detected and detained at the town of Varennes and returned to Tuileries Palace. Count Axel von Fersen, a Swede, was an accomplice who worked disguised as a coachman in Paris. The next day, he got the information of their failure.

Fersen then communicated with Marie Antoinette from Brussels in cipher. Marie wrote back indicating that she was safe and warned him not to return to Paris or try to communicate with her. Between the years 1791 and 1792, more than sixty letters were passed between Fersen and Marie Antoinette, written using either cipher or an invisible, white ink. The cipher was a complicated one and followed the pattern of a polyalphabetic substitution cipher. The manuscripts found revealed that a keyword letter was aligned to every letter. Interestingly, since Fersen handled all the ciphered communication between the King and Queen during their escape, it is highly probable that Marie Antoinette also had the cipher.

Read between the lines

Only later were the ciphered letters revealed as love letters by Marie Antoinette to Fersen. Apart from ciphers, they also used invisible ink, despite the problems it posed. It has been documented that Marie Antoinette found the invisible ink quite difficult to handle. And between them, they devised an ingenious way to communicate – lines of plaintext in invisible ink embedded between mindless texts in cipher, using the cipher as a guise.

Modern Interpretation

The next major breakthrough emerged only much later, after the invention of the telegraph, which completely altered ancient modes of cryptography. Frenchman Blaise de Vigenere created a very practical method for a polyalphabetic system, named after him. The Vigenere cipher is a simple polyalphabetic substitution method which uses a series of various Caesar ciphers to encrypt a message. This cipher has been reinterpreted many times and while it was easy to understand and put into practice, it was rendered unbreakable by beginners. Thus, it commonly came to be known as the ‘indecipherable cipher’.

Code Wars

Despite the circuitous and mostly complicated history of cryptography, it wasn’t until the 19th century that major advances were made. Cryptanalysis became quite popular and most European states had teams to work on breaking coded messages. Charles Babbage, the creator of the first prototype of the current computers, had done extensive work on mathematical cryptanalysis, especially of polyalphabetic ciphers. This was later redeveloped and published by Friedrich Kasiski, a Prussian cryptologist.

Charles Babbage’s Analytical Machine

Kerckhoff’s Principle

During that time, cryptography was mainly a culmination of basic rules, developed and reiterated over time. Frenchman Auguste Kerckhoffs’ essays on cryptography laid the cornerstone for military use of the science. These articles scrutinized the state-of-the-art military cryptography of the time and appealed for massive improvements in the French practice. Apart from practical advice and basic rules, it also had six principles of cipher design for the practical age.

These principles emphasized on the simplicity of the key (which could be memorized) and the belief that the cipher should be unbreakable and transmittable by telegraph.

Furthermore, it also stated that the documents should be handled by a single person and the system should be easy, without any requirement of mental strain. However, it was his second principle that became quite popular and came to be known as Kerckhoffs’ principle. It stated that, “The design of a system should not require secrecy and compromise of the system should not inconvenience the correspondents.” This gave an impetus to cryptography and spurred further milestones.


The misuse of cryptography led to the execution of Mata Hari in the early 20th century. Similarly, during World War I, the German naval codes were broken by the Admiralty’s Room 40 (British Naval Intelligence), which perhaps played an important role in detecting German activity in the North Sea, giving Britain an advantage in the battles of Dogger Bank and Jutland.

Black Chamber

Cryptanalysis units sprouted across Europe and were known as the Black Chamber. It started off in 1628 when Frenchman Antoine Rossignol helped the French army by deciphering a captured message and subsequently, defeated the Huguenots. The victory ensured that Rossignol was called upon to decode ciphers for the Government. His method of deciphering the message included two lists – one with the plain elements in the alphabetical order and code elements in a random arrangement, and the other to help with the decoding where the alphabets and numerals in plaintext were random and the code elements in order. After Rossignol’s demise, his son and grandson continued his work. By then, there were many cryptographers in the employment of the French Government. They formed the Cabinet Noir (the Black Chamber).

Surrender of Cornwalis

In the 1700’s “Black Chambers” were common in Europe. The largest one, however, was in Vienna, called the Geheime Kabinets-Kanzlei. It was led by Baron Ignaz de Koch and the organization was mainly used to sift through all the mail coming to foreign embassies, copy these letters, reseal and return them to the post office the same morning. The office also took charge of other political or military interceptions. There were almost a hundred letters read in a day.


The English Black Chamber came into existence due to the efforts of John Wallis in 1701. Before that, he had to solve ciphers for the Government from an unofficial position. When he died, his grandson, William Blencowe, coveted the position. Having been taught by his father, Blencowe was granted the title of Decypherer. In the cryptographic world, the English Black Chamber has the longest history of victories. The Black Chambers of Europe solved many ciphers and were widely successful. But the period of peace tested their usefulness, which was largely miniscule. By 1850, these Black Chambers were dissolved.

Early american ciphers

America had no centralized organization dedicated to cryptography. Here, decryption was undertaken by interested individuals. The first instance of encryption dates back to 1775, when a letter from Dr. Benjamin Church was intercepted. The coded message was suspected to be vital information for the British. However, the revolutionaries were unable to decipher it. Later on, Elbridge Gerry (who went on to become the fifth Vice President) and Elisha Porter solved the cipher. The message proved Benjamin Church guilty of transferring information to the Tories and he was exiled. The cipher was a simple one where each correspondent had a code book. Each word of the message was replaced by a number representing its place in the book. For example, 3.7.9 meant page 3, line 7 and word 9 in the code book.

Ciphers were also employed by the revolutionaries during the American Revolution. General George Washington was informed about the British troops and their movements around New York City through Samuel Woodhull and Robert Townsend. Their code was a cache of numbers which was substituted for words. This was written by Major Benjamin Tallmadge and also used invisible ink for increased security.

Rapid advancements

James Lovell is considered as the father of American Cryptology. He was true to America and helped the revolutionaries decipher the British codes. This helped them gain victory in the war, especially during the final stages. Interestingly, when former Vice President Aaron Burr and his assistant General James Wilkinson were planning to colonize Spain, they were confused regarding possession of the annexed state. Would it belong to the United States of America or Aaron Burr? Taking advantage of the situation, General Wilkinson who was a Spanish agent changed Burr’s coded message, giving a portrayal of Burr’s intentions of making Spain his own country. The letter was intercepted and was brought to the notice of President Thomas Jefferson. Burr was acquitted after a trial but sadly, his reputation was tarnished forever.

us army cipher device

Fascinated by cryptography, President Thomas Jefferson then went on to create a cipher of his own. However, it must be noted that a similar cipher was used by the US Navy a few years before the Jefferson cipher was invented.

Jefferson’s Wheel

In 1795, Thomas Jefferson invented the ‘wheel cipher’, though he didn’t use it much. It basically consisted of a set of wheels where the letters of the alphabet were randomly distributed. The key is the order of the wheels on the axle. Thus, the message could be coded by arranging the letters along the axis of the axle so that the messages are formed. Any other row of such letters can also be employed as ciphertext. But to decode, the recipient must align the ciphertext to the rotational axis. Without the knowledge of the arrangement of symbols on the wheels, a plaintext of any length can be churned out. This makes the cipher a secure one for the first use. But using the same wheels in the same order for multiple occasions can be used for statistical relays.

WWII Enigma Cipher Machine

Developing on the wheel cipher, Colonel Decius Wadsworth created a set of two disks, where one was embedded inside the other, way back in 1817. The outer disk had the letters of the alphabet and numbers 2-8 while the inside disk featured only the alphabets. The disks were put together at a ratio of 26:33. To code a message, the inner disk is turned until the required letter is at the top position along with the number of turns required to result in the ciphertext. The ratio ensures that the repetition doesn’t happen till all the 33 characters of the plaintext have been used. Sadly, Wadsworth wasn’t credited for this design because Charles Wheatstone devised a rather similar machine and took away the limelight.

Codes and World War II

America’s involvement in the Second World War was the result of an intercepted cipher. Known as the ‘Zimmermann Telegram’, this cable from the German Foreign Office was delivered through Washington to its ambassador Heinrich von Eckardt in Mexico. This was an invitation for Mexico to ally with Germany and in return, they were promised the chance to invade the United States of America. This was thwarted as the cipher was intercepted, and played a massive role in getting America involved in World War II.

Overcoming Enigma

During World War II, information could win or lose a battle and cryptanalysis was an integral part of it. The Nazis relied on the Enigma machine which was used for cryptography to secure intelligence which was vital. By this time, mechanical and electromechanical ciphers were widely utilized. After the telegraph, the advent of the radio changed the game and further developments were made when the rotor system of cryptography was used. Radio completely changed the landscape and French radio stations intercepted most German radio transmissions, though the latter used a double columnar transposition called Ubchi, which was not very strong.

Germany utilized cryptography immensely in all its forms. The Polish Cipher Bureau helped with decoding the detailed structure of the Enigma using mathematics while documentation was given by French military intelligence. This was perhaps the biggest breakthroughs in the history of cryptanalysis. The British Cryptanalysis Department was made up of chess masters and mathematicians, who helped in decoding of the Enigma’s encryption. But these officers were not allowed to openly show their achievement at having broken the ciphers fearing the Germany would claim that Britain had not waged a fair war.

Winning wars

The US Navy was able to break into the codes of the Japanese Navy and this helped them gain an edge in the Battle of Midway, ensuring victory. Later on, the highly advanced Japanese diplomatic cipher system with an electromagnetic stepping switch machine, nicknamed “Purple” by the Americans, was broken. The Americans termed the intelligence emerging from Purple as Magic.

The German military also began attempts in earnest, creating “Fish” ciphers, and finally invented the world’s first ever programmable computer, the Colossus, in aid of cryptanalysis. Finally, America created the MI-8 in 1917, a unit dedicated to cryptanalysis. This organization analysed all secret messages, links and codes. This was largely successful after WW I but in 1929, it was decided to have it shut down as it was found inappropriate to “read others’ mail”. An American couple, William Fredrick Friedman and his wife, Elizabeth Smith were a famous couple in cryptography, having devised new methods to solve ciphers through frequency counts and superimposition.

Codes in words

A lot of literature is the perfect foil for cryptography. Take Edgar Allen Poe’s cryptographic uses, for example. He used many systematic methods to decipher in the 1840s. He also went on to advertise his abilities in the Philadelphia paper Alexander’s Weekly (Express) Messenger and invited ciphers to be submitted, of which he solved almost all. Poe wrote a comprehensive essay which was quite handy for amateur British cryptanalysts who were involved in breaking German ciphers during World War I. That apart, ciphers played a vital role in his famous story, “The Gold-Bug”.

Raphael’s Sistine Madonna (c. 1513-1514)

Arthur Canon Doyle’s Sherlock Holmes also used simple ciphers to solve several mysteries. When a cipher was delivered to Holmes, he used the Almanac as the “codebook” to decipher the message. The earliest and most famous of literal ciphers were described by Sir Francis Bacon. The bilateral cipher uses two fonts, one ordinary and the other specially cut. The difference between these two fonts is so minute that it can only be noted through a powerful magnifying glass. Initially, italics were used to communicate but being more ornate; they offered a perfect disguise for the plaintext. Shakespeare’s four folios use this cipher throughout the text, where almost entire scenes have been added. The bilateral cipher was not just restricted to Bacon and Shakespeare but was used for over a century after their deaths. However, this cipher is impossible to use now due to standardization of the text for publishing which is pre-set.

Musical ciphers

Quite uncommon was the musical cipher where musicians exchanged notes of music for the letters of alphabet. Two people can converse by merely playing a few notes on the piano. They can be involved to a point of no return. The trick is to mildly alter the composition without changing the arrangement. However, the scope of musical cipher is largely limited. It was believed that many such music compositions by Sir Francis Bacon are existent even now.

Picture this

The pictorial cipher was quite popular and is basically a picture or diagram which reveals more than its obvious meaning. Egyptian symbolism is rich in pictorial ciphers and diagrams of alchemists and philosophers reveal hidden layers. The detailing in the images can make a cipher of this sort rather complicated. For example, codes can be hidden in the ripples on the surface of water or by the number of stones in a wall. Montaigue’s Essays use the pictorial cipher rather wisely. The initial B is formed with the help of two arches and an F aided by a broken arch. Sometimes, these pictures are accompanied with a key. This was used extensively in art to show meaning in the depths of colour.

Popular examples of pictorial ciphers include Leonardo Da Vinci’s Last Supper which created a furore over the relationship between Jesus and Mary Magdalene as well as the hotly debated fifth finger on the Pope’s hand in Raphael’s Sistine Madonna. The same artist chose to add a sixth toe on Joseph’s foot in his painting, Marriage of the Virgin. These are brilliantly concealed cryptograms.

Religious ciphers

Acroamatic ciphers were the religious and physical writings of all nations, where allegories and parables are often the sources of cryptography. Since time immemorial, parables and allegories have been used to present the truth in an easy-to-understand manner. This is a pictorial cipher drawn in words and understood through symbolism. It includes the Old and New Testaments of the Jews, the works of Plato and Aristotle, Homer’s Odyssey and Iliad, Aesop’s Fables and Virgil’s Aeneid. This is the most subtle cipher and can be interpreted in many different ways.

Indian elements

Cryptography was mentioned in the Kamasutra, written way back in the 4th century AD. Based on the manuscripts, it recommends that women should study 64 arts and one of them was the art of secret writing (mlecchitavikalpa), so that they can hide the details of their liaisons. Early prototypes included a simple system where random pairing of the alphabets was followed by substitution with letters from a cipher. The government also employed secret codes to communicate with spies distributed across the country. Apart from ciphers based on substitution, they also relied heavily on spoken or sign language communication.

Modern cryptography

While Vigenere’s cipher was unbeatable for many, many years, all that was about to change as Charles Babbage added his unique element to cryptanalysis. An independent and wealthy Englishman, Babbage was credited for his work in computer science. He hacked systems in search of a repeated sequence of letters. Babbage’s indigenous technique created waves and took cryptography to the next level, introducing mathematics in place of words.After World War II, most cryptography was mathematical in approach, thanks to the easy availability of computers and the discovery of the internet as a communication tool. Shannon was the frontrunner of modern cryptography, relying mostly on mathematics. His extensive work during WWII and publication in the technical journals laid a theoretical base for mathematical cryptography. This was immediately utilized by secret Government organizations like GCHQ and NSA.

Public key cryptography

In 1970s, the Data Encryption System (DES) made its entry, proposed by a research team at IBM, in a bid to secure electronic communication. This would immensely help business facilities for banks and other financial concerns. After creating a furore, the DES soon became obsolete and was replaced by the Advanced Encryption Standard (AES). Rijndael, a program developed by two Belgian cryptographers were believed to be secure and are still used today. However, this can be highly vulnerable to brute attacks.

Back to the future

The biggest recent development occurred when the Public Key was developed, where a new method of key distribution was introduced. The Diffie-Hellman key exchange created a new class of coding algorithms, using asymmetric keys. Before that, all the keys were rather symmetric in approach, which brought with it a host of problems including the availability of secure channels, especially as the number of participants increase. But the asymmetric key utilizes mathematical keys to decrypt the encryption. By designing a private and public set of keys, the requirement of a secure channel is diminished.

These early ciphers laid the foundation for their modern day counterparts, much more advanced and better suitable for delicate transactions. Right from credit card transactions to internet safety, cryptography is now an integral part of our lives. And its importance has only been multiplied in recent times.