Types of Ciphers: A Complete Guide to Early and Modern Codes
- Ezra Sandzer-Bell
- Feb 26
- 9 min read
Updated: Mar 21
The earliest ciphers in popular history were used to communicate messages privately between partners. One person used a key to translate readable information (called plaintext) into scrambled, unreadable text (ciphertext). The receiver would need to have that same key in order to decipher the message.
Over thousands of years, ciphers have evolved from coded messages into the creative arts and became part of a movement called Cypherpunk, at the heart of cryptocurrency, bitcoin and online encryption protocols.
This article will include an overview of the most common ciphers and how they work. We'll follow that thread into modern applications to music, cryptocurrency and internet privacy.
Table of Contents
Cipher definition: The origin of the word
The origin of the English word cipher can be traced back through multiple languages, to the Arabic word ṣifr (صِفْر) meaning zero or empty.
Arabic Origin (ṣifr, صفر) - The Arabic word "ṣifr" literally means "empty," "zero," or "nothingness."
Medieval Latin Adoption (cifra, zephirum) - Europeans first encountered the Arabic numeral system through translations of mathematical texts. Medieval Latin scholars transliterated the Arabic term into forms like zephirum and eventually "cifra", borrowing the concept of zero and emptiness.
Old French Transformation (cifre) - The Latin "cifra" evolved into Old French as "cifre", originally still meaning "zero" or "nothing."
Middle English (cifer) - Around the 14th century, English speakers borrowed "cifre" from French, spelling it "cipher". Encrypted writing seemed to have "zero meaning" for those who lacked the decryption key.
The circular shape of the Arabic zero was also important during the Middle English period. Most cryptograms were based on letter substitution and transposition with a circular "Cipher Wheel". These keys relied on rotating inner and outer circles for both the encryption and deciphering of secret messages.
Common ciphers from classic and modern history
Classical ciphers centered on substitution and transposition of alphabet letters or numbers. These are the types of ciphers that you'll typically read about in a standard account from historians. We'll review the most common examples here.
Atbash Cipher
This ancient monoalphabetic cipher (single letter to single letter) began with the Hebrew alphabet. Atbash reverses the alphabet so that the first letter maps to the last, creating a simple yet historically notable encryption method.
Gematria
This alphanumeric system substituted each letter for a numerical value. It was common in both ancient Hebrew and Greek civilization. They each used alphabet letters to count as part of every day life. However, the religious practitioners privately added up the numerical value of words and saw mystical significance when two words had the same numerical value.
Caesar Cipher
Julius Caesar popularized this simple substitution technique by shifting the plaintext letter by a fixed number within the alphabet. While easy to implement, it was the simplest to decode and vulnerable to interception. If an outsider notices the repeated use of certain phrases like "a" and "the", they can use that to quickly break the code.
Vigenere Cipher
This polyalphabetic substitution method uses multiple alphabets to encrypt data, significantly improving security by disrupting frequency analysis. It was invented in 1553 by the Italian cryptographer Giovan Battista Bellaso, and named after French cryptographer Blaise de Vigenère, who proposed a similar cipher in 1586.
To set up this cipher, the full English alphabet is used to create a xy coordinate system as shown above. Next, a "key" is selected by the sender and receiver, for example the word "COVER". That key is applied downward along the Y axis and for each letter in that key, the operator maneuvers along the X axis to the plaintext letter. The intersecting letter between the X and Y axis gives you your cipher letter.
Playfair Cipher
This is a more complex classical cipher that encrypts pairs of characters rather than single letters. A 5x5 grid of the alphabet is set up, with the letters I and J used interchangeably. The graphic above show how two-letter bigrams are used to define end points of a rectangle. Some basic rules are then set up for how letters are swapped within that rectangular shape.
Columnar Transposition Cipher
This system uses two encryption keys; the key is a word and the second is a "sequence" indicating a re-arrangement of the key word. The number of letters in the key defines the number of columns and the sequence defines which letter goes in each column header.
An example of this is shown in the graphic above, where the 12-letter key "permutations" creates a 12-column matrix. The plaintext message beginning with "I pulled the lever..." wraps around those twelve columns. Next, the sequence is applied to reorder those columns, as if dragging them around in a spreadsheet. Finally, the key is removed so that only the encrypted message remains.
Affine Cipher
This system maps each alphabet letter to its numeric equivalent (A=0, B=1, C=2) and then applies a simple modular arithmetic formula to reconvert it into ciphertext.
In the example above, the number value of each alphabet letter is defined by the variable X and passed through a random selected formula (5x + 8) that acts as the encryption key.
Since the outputs exceed the 26 letters of the alphabet, a mod26 rule is applied, meaning you keep subtracting 26 from the output value of a letter until it's within the 0-25 parameters. 48 becomes 22 and is converted to the corresponding letter.
Baconian Cipher
Developed by Francis Bacon, this method uses a 5-bit binary encoding, as shown in the graphic above. First, each letter is swapped for a short code consisting of five units (either 0 or 1). Multiply the number of letters in the message by 5 and then write a phrase of that length. Then finally, change the type face whenever the binary is equal to one.
In the demo above, I've encoded the word "cat" into its 5-bit binary: [aaaba] [aaaaa] [baaba] and used a random phrase with 15 letters: "The dog is an enemy" with bold font as our secondary typeface.
Pigpen Cipher
Also known as the Freemason cipher, Pigpen cipher substitutes each letter with symbols based on a simple geometric grid, making it visually distinct yet straightforward to decode with the correct reference.
The example above shows how a phrase like "X marks the spot" is translated into a geometric code. Several other geometric variations have been used across the history of secret societies and mystical orders like the Rosicrucians.
Zodiac Cipher (aka 340 Cipher)
Perhaps one of the more frightening examples of substitution ciphers in history was the 340 Cipher, made popular by a serial murderer who called himself the Zodiac Killer. The code remained unsolved for decades due to its complexity. It utilizes a complex substitution system with irregular patterns, making it notably challenging to decipher. The cracked code can be seen in the graphic above.
Each of these encoding protocols has its own rich history worthy of exploration. In the interest of covering all of our bases, we're going to move on to some related topics that are often overlooked when authors cover the types of ciphers that exist.
Music ciphers and their cultural influencer over time
Melodic ciphers are among the lesser known ciphers, but were nevertheless well documented throughout history. We've written about them in great detail in our article here on musical cryptograms.
Letter to music-note encryption
One of the earliest recorded examples of a musical cipher was by John Wilkins in his 1641 publication titled "Mercury, or The Secret and Swift Messenger". He briefly described how musical scores could be used to conceal secret information.
People from an assortment of backgrounds, including spies, composers and mystics all followed his lead in the years that followed. The examples below feature a few possible techniques, including simple letter-to-note substitution and more elaborate letter-to-motif substitutions.
A handful of European composers, beginning with Johann Sebastian Bach, created their own "musical signatures" by encoding their name into compositions using letters from their surname.
Check out our article on musical easter eggs for more examples of this tradition, beyond the scope of cryptography alone. Very few artists have openly used musical cryptograms in modern genres. The music video below features one such example in the song "Comet" by the post-rock band Hazel.
I've time stamped the video to take you to the chorus, where the lead vocals sing "And Everywhere Comets Flare" while the background vocals sing "A E C F", an acronym for each letter of the chorus. Those four letters are mirrored by the four-chord progression played in the guitar, and this qualifies as a musical cipher.
Rap cyphers: Encoding secret meaning into lyrics
It's more common to find secret meanings in the lyrics of songs. The best example of this is in a rap cypher, where artists place several layers of meaning, metaphors, and wordplay. Without the proper cultural context, it's not possible to understand or decipher the entire meaning.
Entire sites have been dedicated to decoding rap cyphers. The best example of this is probably Genius, a site where users can openly annotate song lyrics and provide context for the deeper meaning of short lyrical ideas or bars.
A cypher typically refers to a group event where multiple people take turns rapping while an audience stands by and watches. Battle rap events hosted by major leagues, like King of the Dot, are currently at the epicenter of rap cyphers.
Solo freestyle lyricists like Harry Mack and Ari at Home have also taken to the streets in recent years, promoting a less combative and more "positive" or supportive take on the culture.
Modern Ciphers: Cypherpunk and internet privacy
As cryptography evolved, classical ciphers gave way to modern ciphers designed to secure digital data against sophisticated threats and unauthorized access.
The cypherpunk or crypto punk movement emerged prominently during the late 1980s and early 1990s as a reaction against growing concerns over digital privacy and government surveillance. Enjoy the video documentary below for a deep dive on their history, core values, and impact on the world today.
Cypherpunks advocated for the widespread availability of robust encryption technologies, believing that individual privacy is fundamental and should be protected against unauthorized intrusion by governments or other entities.
Central to the cypherpunk philosophy is the idea of decentralization, the elimination of reliance on centralized authorities for securing personal and financial information. This concept directly inspired the creation and development of blockchain technology, laying the foundation for cryptocurrencies like Bitcoin.
Blockchain encryption protocols
Blockchain’s decentralized structure, combined with advanced cryptographic techniques, ensures transparency while maintaining security and anonymity, embodying key principles of cypherpunk ideals.
Cypherpunk also significantly influenced modern encryption standards and tools widely adopted today, pushing cryptographic methods into mainstream usage. Tools like Pretty Good Privacy (PGP), created by Phil Zimmermann, became symbolic of the cypherpunk ethos by empowering users to secure their own communications independently.
Today, the legacy of cypherpunk can be seen in the robust encryption mechanisms underlying secure messaging applications, online banking, digital identities, and secure transaction protocols essential to our contemporary digital infrastructure.
Symmetric key encryption
Symmetric Key Encryption: Symmetric ciphers, using a single secret key for both encryption and decryption, are widely employed for their efficiency in handling large amounts of data.
Here are some key concepts, including block ciphers and stream ciphers.
Block Ciphers: Block ciphers divide plaintext into fixed-size blocks, encrypting each with a cipher algorithm and a secret key. The encryption process in block ciphers often employs modes of operation like ECB or CBC to enhance security.
Stream Ciphers: Unlike block ciphers, stream ciphers encrypt data continuously, one character or bit at a time, making them highly efficient for streaming applications.
Asymmetric Key Algorithms (Public Key Cryptography): Modern cryptography also utilizes asymmetric key algorithms, involving pairs of keys—a public key for encrypting and a private key for decrypting. Public key cryptography significantly enhances security, especially in scenarios like secure messaging and online banking.
Secret Key: In symmetric key encryption, the secrecy and key length directly influence security. Longer keys generally provide better defense against brute-force attacks.
Encryption Algorithm: The robustness of encryption methods largely depends on the strength of the encryption algorithm and proper management of encryption keys.
Modern ciphers underpin vital daily operations, from protecting personal information against unauthorized access to securing cryptocurrency transactions. Strong encryption methods are essential to safeguarding sensitive data in an increasingly digital world.
I hope this article has helped illuminate that there are many types of ciphers, from the classic monoalphabetic substitution methods to modern symmetric and asymmetric algorithms. Musical codes also play a lesser known but very important role in the history of Western culture.
