We’ve been hiding important messages since we first started sending them. Most ancient civilizations have their mysteries and they often included ciphers, codes, and other encryption systems in some form or another to prevent unauthorized persons from interpreting these messages.
The messages would be transported back and forth by speedy and stealthy couriers: the keyword being stealth (and the desire not to get caught). Because if the message was intercepted, the contents were likely to get into the wrong hands and be misused. To avoid this possibility, ancient codes and ciphers were crafted with such high levels of precision and perfection that many of them remain undeciphered to this day.
Steganography is a centuries-old technique for hiding messages “in plain sight” by disguising them as something else. Although Johannes Trithemius coined the term in 1499 in his Steganographia (a treatise on cryptography and steganography disguised as a book about magic), traces of steganography can be traced back to Ancient Greece, when Herodotus described two examples of such practices in his Histories.
In his Histories, Herodotus recounts how Histiaeus interacted with his vassal, Aristagoras, by shaving off all of a slave’s hair, “imprinting” the message onto his skin then waiting for the slave’s hair to regrow. The slave was then brought to Aristagoras, who would shave his head once more to get the secret communication. Most examples of steganography these days involve the placement of a secret bit of text inside an image or picture. Alternatively, you could conceal a secret message or script within a Word or Excel document.
9. The Caesar Shift
The Caesar shift is a straightforward cipher named after Julius Caesar, who used it to encrypt his personal as well as military letters. To use it, simply shift each letter of the alphabet by a specific number of letters to the left or right. By shifting three spaces to the left, for example, E becomes B, F becomes C, and so on. Although it is an incredibly simple code, it took ancient codebreakers over 700 years to crack it – and almost a Millennium to come up with a compelling substitute.
Components of the Caesar cipher are frequently used in more complex encryptions, including the Vigenere cipher, and are still being applied in the ROT13 system, which is a basic letter replacement cipher that substitutes a letter with the 13th letter in the alphabet that comes after it. The Caesar cipher, like all single-alphabet substitution ciphers, is easily broken and provides no communication security in modern practice.
8. The Vigenère Square
The Vigenère cipher uses a sequence of interwoven Caesar ciphers based on the letters of a keyword to encrypt alphabetic text. In other words, it uses a polyalphabetic replacement technique. The cipher, which was first described in 1553 by Giovan Battista Bellaso, is simple to learn and use, but it defied all efforts to break it until 1863, three hundred years later. This earned it the moniker “Le Chiffre indéchiffrable” (French for “the indecipherable cipher”).
Many people have attempted to use encryption techniques based on Vigenère ciphers. Friedrich Kasiski published the first broad method of deciphering Vigenère ciphers in 1863. However, the technique was wrongly attributed to Blaise de Vigenère (1523–1596) in the nineteenth century and thus received its current name.
7. The Ave Maria Code
The German abbot, Johannes Trithemius, wrote the first printed book on cryptography, but his clandestine and misunderstood writings led to numerous accusations that he was collaborating with the devil, and he ultimately had to relinquish his position. The Ave Maria cipher is one of his most famous codes. To understand the code, one merely needs to use the various tables appearing in Polygraphia, a book that contains 384 columns of alphabet letters, each with a corresponding code phrase, and each coded letter is substituted by a short Latin sentence about Jesus.
Let’s imagine you wanted to encrypt the word “tomorrow.” Using Trithemius’ tables, you will then write down the matching word for each character from the successive columns. To reveal the word, the recipient repeats the process in reverse. Anyone intercepting the letter or note, which contains a long list of Latin phrases, would likely misinterpret it as a prayer, making it unlikely to raise suspicion.
6. The Voynich Manuscript
Wilfrid Michael Voynich, a Polish-born antiquarian bookseller, purchased 30 books from a Jesuit college in Italy in 1912, including a vellum codex dating from the 1400s. The 240 pages of what has become known as the Voynich Manuscript, are covered in over 170,000 strange symbols and characters. There are botanical specimens and astrological drawings on nearly every page, with the more odd ones depicting female nudes with swollen bellies.
Professional codebreakers and scholars from numerous fields have attempted to solve its riddle throughout the years. Many enthusiasts, including the authors of a computer algorithm-based study published in 2016, believe that Hebrew is the dialect behind the script, however experts disagreed with the methods they utilized, and no reliable translation could be generated. Others feel the manuscript is a fabrication or hoax. To date, no one has been able to decipher the document, and none of the many hypotheses presented over the last century has been independently confirmed. The enigma surrounding its meaning and origin has piqued the public’s interest, prompting a lot of speculation and interest.
5. The Great Paris Cipher
The Great Cipher, also known as Grand Chiffre, was a nomenclature cipher invented by the Rossignols, a family of cryptographers who served the French Crown for several generations. It is one of the most well-known codes and ciphers in the history of the world. The Great Cipher got its name from its excellence and the fact that it was said to be unbreakable. The French Peninsular army used modified forms of the code until the summer of 1811, and many records in the French archives became unreadable once they were no longer in use.
A set of 587 digits representing syllables served as the foundation for the code that was finally cracked by Bazeries. Other variations existed, and Louis XIV’s foreign ministers received separate code sheets encrypting not only syllables but also letters and complete words. Some number sets were “nulls” meant to be ignored by the intended recipient to avoid detection through frequency analysis. Others were set up as traps, such as a code group that was supposed to ignore the preceding one.
4. Bellaso Cipher
Giovan Battista Bellaso, an Italian cryptographer, recognized the value of utilizing numerous alphabets to encrypt messages during the 16th century. He wrote and published three books, each with a different variation on his encryption methods, eventually using ten alphabets.
For the most basic implementation of his method, a table is created by dragging the bottom portion of a conventional alphabet for a seemingly unrelated number of places in regard to the upper half. In fact, the table can be memorized by sliding the lower portion one position to the right and following the alphabetic order of the letters – vowels first, consonants second. The plaintext is encoded by placing an agreed-upon word, called countersign, over it. The plaintext letter is replaced with the letter above or below it in the alphabet designated by the capital letter of the countersign, using the table as a guide. It’s worth noting that several letters in the original message can be encoded as the same cipher letter, which can cause confusion for anyone intercepting it.
3. Dorabella Cipher
In July 1897, composer Sir Edward Elgar was invited to see Reverend Alfred Penny. After the visit, Elgar sent the family a thank-you note, along with a perplexing message for their 23-year-old daughter, Dora. The message was composed of 87 characters that are connected semi-circles that are oriented in one of eight distinct yet different ways.
Dora maintains that she has never deciphered the message. However, Dora is the name of one of Enigma’s renowned variations, which suggests a conceivable link – albeit unverified. According to some codebreakers, the cipher is actually a coded musical piece, with the orientations indicating notes and the number of semicircles corresponding to natural, flat, and sharp notes.
2. Pigpen Cipher
Because of its ancient origins, the Pigpen Cipher is also known as the Masonic or Freemason Cipher. The cipher employs 26-character keys, each of which replaces a character in the alphabet with a separate but distinct symbol. Though dots and grids are the primary components of the cipher, images also frequently include Xs. This cipher has several variants, each with corresponding structures and elements but different symbols. When a letter appears, it is replaced by a specific symbol assigned to the letters through the use of a key.
While the true origins of the cipher are unknown, it is thought to have originated with ancient Hebrew rabbis; evidence has also been discovered that the Knights Templar used one during the Christian Crusades in the Middle Ages. Its appearance faded during the 18th century, when Freemasons used it to keep lodge records and rites private, as well as for correspondence between lodge heads and brothers. Ciphered phrases and messages are frequently found etched on the tombstones of Freemasons and were also used by Union prisoners in Confederate prison camps during the Civil War.
1. Scytale Cipher
The oldest item on this list is the Scytale cipher, which was used by the Ancient Greeks and Spartans to keep their communications private during military campaigns. It consisted of a cylinder with a piece of parchment wrapped around it on which orders or other directions were written. The first mention of its use was by the Greek poet Archilochus in the 7th century BC, but Apollonius of Rhodes, a poet and Homeric scholar who also worked as a librarian at the Royal Library of Alexandria, was the first to provide a convincing indication of its use as a cryptographic technique in his writings.
Researchers have deduced that the Scytale was used to communicate a transposition cipher based on the ancient descriptions. Another theory is that the Scytale was used to authenticate messages rather than encrypt them. The message could only be read if the sender wrapped it around a Scytale with the same diameter as the receivers. As a result, hostile spies would have a hard time injecting false messages into the contact between two commanders.