Category: Classical ciphers

In cryptography, a scytale (/ˈskɪtəliː/; also transliterated skytale, Ancient Greek: σκυτάλη skutálē "baton, cylinder", also σκύταλον skútalon) is a tool used to perform a transposition cipher, consis
Copiale cipher
The Copiale cipher is an encrypted manuscript consisting of 75,000 handwritten characters filling 105 pages in a bound volume. Undeciphered for more than 260 years, the document was cracked in 2011 wi
Alberti cipher
The Alberti Cipher, created in 1467 by Italian architect Leon Battista Alberti, was one of the first polyalphabetic ciphers. In the opening pages of his treatise he explained how his conversation with
Nihilist cipher
In the history of cryptography, the Nihilist cipher is a manually operated symmetric encryption cipher, originally used by Russian Nihilists in the 1880s to organize terrorism against the tsarist regi
Bacon's cipher
Bacon's cipher or the Baconian cipher is a method of steganographic message encoding devised by Francis Bacon in 1605. A message is concealed in the presentation of text, rather than its content.
Caesar cipher
In cryptography, a Caesar cipher, also known as Caesar's cipher, the shift cipher, Caesar's code or Caesar shift, is one of the simplest and most widely known encryption techniques. It is a type of su
Polyalphabetic cipher
A polyalphabetic cipher is any cipher based on substitution, using multiple substitution alphabets. The Vigenère cipher is probably the best-known example of a polyalphabetic cipher, though it is a si
Two-square cipher
The Two-square cipher, also called double Playfair, is a manual symmetric encryption technique. It was developed to ease the cumbersome nature of the large encryption/decryption matrix used in the fou
The DRYAD Numeral Cipher/Authentication System (KTC 1400 D) is a simple, paper cryptographic system employed by the U.S. military for authentication and for encryption of short, numerical messages. Ea
Pig Latin
Pig Latin is a language game or argot in which words in English are altered, usually by adding a fabricated suffix or by moving the onset or initial consonant or consonant cluster of a word to the end
Transposition cipher
In cryptography, a transposition cipher is a method of encryption which scrambles the positions of characters (transposition) without changing the characters themselves. Transposition ciphers reorder
Atbash (Hebrew: אתבש; also transliterated Atbaš) is a monoalphabetic substitution cipher originally used to encrypt the Hebrew alphabet. It can be modified for use with any known writing system with a
Classical cipher
In cryptography, a classical cipher is a type of cipher that was used historically but for the most part, has fallen into disuse. In contrast to modern cryptographic algorithms, most classical ciphers
Running key cipher
In classical cryptography, the running key cipher is a type of polyalphabetic substitution cipher in which a text, typically from a book, is used to provide a very long keystream. Usually, the book to
Arnold Cipher
The Arnold Cipher was a book cipher used by John André and Benedict Arnold during the negotiations that led to Arnold's failed attempt to surrender West Point to the British in 1780.
Poem code
The poem code is a simple, and insecure, cryptographic method which was used during World War II by the British Special Operations Executive (SOE) to communicate with their agents in Nazi-occupied Eur
Autokey cipher
An autokey cipher (also known as the autoclave cipher) is a cipher that incorporates the message (the plaintext) into the key. The key is generated from the message in some automated fashion, sometime
Vigenère cipher
The Vigenère cipher (French pronunciation: ​[viʒnɛːʁ]) is a method of encrypting alphabetic text by using a series of interwoven Caesar ciphers, based on the letters of a keyword. It employs a form of
ROT13 ("rotate by 13 places", sometimes hyphenated ROT-13) is a simple letter substitution cipher that replaces a letter with the 13th letter after it in the alphabet. ROT13 is a special case of the C
Bifid cipher
In classical cryptography, the bifid cipher is a cipher which combines the Polybius square with transposition, and uses fractionation to achieve diffusion. It was invented around 1901 by Felix Delaste
Pigpen cipher
The pigpen cipher (alternatively referred to as the masonic cipher, Freemason's cipher, Napoleon cipher, and tic-tac-toe cipher) is a geometric simple substitution cipher, which exchanges letters for
Alphabetum Kaldeorum
The Alphabetum Kaldeorum ("alphabet of the Chaldeans") is one of the best known ciphers of the Middle Ages. Its name refers to Chaldea, whose inhabitants during the medieval era were reputed to have m
Tap code
The tap code, sometimes called the knock code, is a way to encode text messages on a letter-by-letter basis in a very simple way. The message is transmitted using a series of tap sounds, hence its nam
Affine cipher
The affine cipher is a type of monoalphabetic substitution cipher, where each letter in an alphabet is mapped to its numeric equivalent, encrypted using a simple mathematical function, and converted b
Mlecchita vikalpa
Mlecchita Vikalpa is one of the 64 arts listed in Vatsyayana's Kamasutra. The list appears in Chapter 3 of Part I of Kamasutra and Mlecchita Vikalpa appears as the 44th item in the list. The term Mlec
Straddling checkerboard
A straddling checkerboard is a device for converting an alphanumeric plaintext into digits whilst simultaneously achieving fractionation (a simple form of information diffusion) and data compression r
Polybius square
The Polybius square, also known as the Polybius checkerboard, is a device invented by the ancient Greeks Cleoxenus and Democleitus, and made famous by the historian and scholar Polybius. The device is
Āryabhaṭa numeration
Āryabhaṭa numeration is an alphasyllabic numeral system based on Sanskrit phonemes. It was introduced in the early 6th century in India by Āryabhaṭa, in the first chapter titled Gītika Padam of his Ar
Trifid cipher
The trifid cipher is a classical cipher invented by Félix Delastelle and described in 1902. Extending the principles of Delastelle's earlier bifid cipher, it combines the techniques of fractionation a
Four-square cipher
The four-square cipher is a manual symmetric encryption technique. It was invented by the French cryptographer Felix Delastelle. The technique encrypts pairs of letters (digraphs), and thus falls into
Reservehandverfahren (RHV) (English: Reserve Hand Procedure) was a German Naval World War II hand-cipher system used as a backup method when no working Enigma machine was available. The cipher had two
Wadsworth's cipher
Wadsworth's cipher, or Wheatstone's cipher, was a cipher invented by Decius Wadsworth, a Colonel in the United States Army Ordnance Corps. In 1817, he developed a progressive cipher system based on a
The M-94 was a piece of cryptographic equipment used by the United States Army, consisting of several lettered discs arranged as a cylinder. It was also employed by the US Navy, under the name CSP 488
Sheshach (Hebrew: ששך), whose king is mentioned in the Hebrew Bible in Jeremiah 25:26, is supposed to be equivalent to Babel (Babylon), according to a secret mode of writing practiced among the Jews o
Beaufort cipher
The Beaufort cipher, created by Sir Francis Beaufort, is a substitution cipher similar to the Vigenère cipher, with a slightly modified enciphering mechanism and tableau. Its most famous application w
Tabula recta
In cryptography, the tabula recta (from Latin tabula rēcta) is a square table of alphabets, each row of which is made by shifting the previous one to the left. The term was invented by the German auth
Rail fence cipher
The rail fence cipher (also called a zigzag cipher) is a classical type of transposition cipher. It derives its name from the manner in which encryption is performed, in analogy to a fence built with
The Reihenschieber (English: Row Slider) was a hand cipher system used by the German Bundeswehr. It was developed during 1957 and used until the early 1960s, although information about the system was
Grille (cryptography)
In the history of cryptography, a grille cipher was a technique for encrypting a plaintext by writing it onto a sheet of paper through a pierced sheet (of paper or cardboard or similar). The earliest
Shackle code
A shackle code is a cryptographic system used in radio communications on the battle field by the US military and the Rhodesian Army.It is specialized for the transmission of numerals.Each of the lette
Thomas Brierley grave cipher
The gravestone of Thomas Brierley (1785 – 1854 or -55) in Mellor, Greater Manchester, is one of the only ones in the United Kingdom known to incorporate masonic pigpen cypher in its inscription. Anoth
Great Cipher
The Great Cipher (French: Grand chiffre) was a nomenclator cipher developed by the Rossignols, several generations of whom served the French monarchs as cryptographers. The Great Cipher was so named b
The Alphabet Cipher
Lewis Carroll published "The Alphabet-Cipher" in 1868, possibly in a children's magazine. It describes what is known as a Vigenère cipher, a well-known scheme in cryptography. While Carroll calls this
The Chaocipher is a cipher method invented by John Francis Byrne in 1918 and described in his 1953 autobiographical Silent Years. He believed Chaocipher was simple, yet unbreakable. Byrne stated that
Hill cipher
In classical cryptography, the Hill cipher is a polygraphic substitution cipher based on linear algebra. Invented by Lester S. Hill in 1929, it was the first polygraphic cipher in which it was practic
Book cipher
A book cipher, or Ottendorf cipher, is a cipher in which the key is some aspect of a book or other piece of text. Books, being common and widely available in modern times, are more convenient for this
ADFGVX cipher
In cryptography, the ADFGVX cipher was a manually applied field cipher used by the Imperial German Army during World War I. It was used to transmit messages secretly using wireless telegraphy. ADFGVX
Rasterschlüssel 44
Rasterschlüssel 44 (abbr. RS 44) was a manual cipher system, used by the German Wehrmacht during the Second World War. The cipher was designed by the astronomer and sometime cryptographer Walter Frick
Substitution cipher
In cryptography, a substitution cipher is a method of encrypting in which units of plaintext are replaced with the ciphertext, in a defined manner, with the help of a key; the "units" may be single le
Playfair cipher
The Playfair cipher or Playfair square or Wheatstone–Playfair cipher is a manual symmetric encryption technique and was the first literal digram substitution cipher. The scheme was invented in 1854 by
VIC cipher
The VIC cipher was a pencil and paper cipher used by the Soviet spy Reino Häyhänen, codenamed "VICTOR". If the cipher were to be given a modern technical name, it would be known as a "straddling bipar
Wahlwort (nonsense word or filler) is a cryptographic term used particularly in connection with the Wehrmacht, which used wahlworts on their Enigma rotor machine in the encryption of their communicati
Null cipher
A null cipher, also known as concealment cipher, is an ancient form of encryption where the plaintext is mixed with a large amount of non-cipher material. Today it is regarded as a simple form of steg