Obfuscation

The Zodiac Cipher is a symbolic substitution cipher that encodes plaintext letters into a set of distinct Zodiac-themed symbols. Unlike historical cryptograms associated with the Zodiac Killer, this version is purely thematic, using visual symbols inspired by astrological signs to represent letters of the alphabet. The cipher is typically monoalphabetic, meaning each plaintext letter maps to a single symbol, but it can be adapted with a keyword to shuffle the symbol order for added security.

The Tap Code is a manual cipher system used for encoding messages through a series of taps, knocks, or other simple signals, and was popularized for covert communication among prisoners of war in the 20th century, particularly during World War II and the Vietnam War. It is essentially a numeric substitution cipher based on a 5×5 Polybius square in which letters are assigned coordinates, with C and K sharing a single position.

The Patristic Cipher, also known as a Patristocrat, is a form of monoalphabetic substitution cipher specifically designed to conceal word boundaries and sentence structure. Unlike a standard substitution cipher where spaces are preserved, the Patristic Cipher removes all spaces and punctuation from the plaintext and then regroups the resulting ciphertext into uniform blocks, traditionally of five letters. This visual flattening makes frequency analysis more difficult and forces the solver to reconstruct word breaks mentally.

The Nihilist Cipher is a classical cipher combining fractionation and polyalphabetic substitution, invented by the Russian-Jewish revolutionary and cryptographer F. K. Nihilist in the 1880s. It gained practical notoriety among Russian revolutionary groups for clandestine communication. The cipher operates by first converting plaintext letters into numbers using a Polybius square, then adding a numeric key sequence to these numbers to create the ciphertext.

The M-94 Cipher is a mechanical polyalphabetic cipher device used by the United States military, based on the earlier Jefferson Disk cipher invented by Thomas Jefferson in 1795. It was officially adopted in the early 20th century, around 1922, to provide secure field communication before the widespread use of electronic encryption machines. The device consists of a set of rotating disks mounted on a cylinder, each disk engraved with a scrambled alphabet.

The Letter Number Substitution cipher is a classical substitution method in which each letter of the alphabet is replaced by a corresponding number. Its origins are difficult to trace precisely, as variations of letter-to-number mapping have existed since ancient times, but it became widely referenced in cryptographic manuals during the 19th century for educational and puzzle purposes. The method provides a simple way to transform text into a numeric sequence while remaining reversible, making it suitable for manual encryption and early secret messaging.

The Jefferson Disk cipher, also known as the Wheel Cipher, is a classical mechanical cipher invented by the American statesman Thomas Jefferson around 1795. It consists of a set of rotating disks, each engraved with the letters of the alphabet in a scrambled order, mounted on a spindle. By arranging the disks in a particular sequence determined by a key, a plaintext message can be encoded into a seemingly random string of letters. Decryption requires the recipient to have an identical set of disks arranged in the same order.

The Morse Code is a method of encoding textual information using sequences of short and long signals—commonly called “dots” and “dashes”—invented by the American artist and inventor Samuel F. B. Morse and his collaborator Alfred Vail in 1837. Originally developed for telegraph communication, Morse Code translates letters, numbers, and punctuation into variable-length sequences of electrical pulses, audible tones, or visual signals, allowing messages to be sent across long distances using a binary-like system.

The Index Card cipher is a classical manual cipher system that emerged in the 19th century as a practical tool for secure correspondence, particularly in diplomatic and military contexts. While its precise inventor is unknown, the method builds on principles of transposition and substitution, using small cards or slips—each containing a portion of the alphabet, numbers, or symbols—to systematically encode messages.

The Cardan Grille cipher is a classical steganographic and transposition cipher invented by the Italian mathematician and polymath Girolamo Cardano in 1550. It is notable for its use of a physical device—a perforated grille—through which a plaintext message is written on a blank sheet of paper. The holes in the grille determine which letters are visible, while the remaining spaces are filled with nulls or random letters, creating a concealed message.