Cipher methods
Cipher methods
Every method used in CipherChronicle is documented here: origin, principle, worked example, known weaknesses and links to the grids that use it.
83 method(s) shown
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caesar
BeginnerCaesar cipher
A fixed alphabet shift. The classic — easy to grasp, easy to break.
Substitution Read the page -
rot-13
BeginnerROT-13
A special case of Caesar (shift 13, involutive).
Substitution Read the page -
atbash
BeginnerAtbash
A full alphabet flip. A ↔ Z, B ↔ Y.
Substitution Read the page -
vigenere
IntermediateVigenère cipher
A Caesar whose key changes at every letter. Long thought unbreakable.
Polyalphabetic Read the page -
rot
BeginnerGeneric ROT
The mother family of shift ciphers: ROT-N for any integer N. ROT-13 and ROT-47 are the iconic ones.
Code Read the page -
substitution
IntermediateMonoalphabetic substitution
A free permutation of the alphabet. 26! options — but frequency gives it up.
Substitution Read the page -
affine
IntermediateAffine cipher
Each letter runs through ax + b mod 26. The algebraic cousin of Caesar.
Substitution Read the page -
rail-fence
BeginnerRail Fence (zig-zag)
Zigzag transposition across rails. Simple, visual, pedagogical.
Transposition Read the page -
caesar-square
BeginnerCaesar square
Text written in rows in a square, read back in columns. The most minimal transposition.
Transposition Read the page -
bacon
BeginnerBacon cipher
Every letter → sequence of 5 A/B symbols. A precursor to binary.
Code Read the page -
morse
BeginnerMorse code
Dots and dashes. Born of the telegraph, still alive on radio.
Code Read the page -
a1z26
BeginnerA1Z26 (alphabet rank)
A = 1, B = 2, …, Z = 26. The most intuitive code to start with.
Code Read the page -
polybius
BeginnerPolybius square
Every letter becomes a pair of coordinates in a 5×5 grid.
Grid Read the page -
beaufort
IntermediateBeaufort cipher
An involutive Vigenère: encryption = decryption.
Polyalphabetic Read the page -
scytale
BeginnerScytale (Spartan rod)
The Spartan rod. The oldest known military cipher device.
Transposition Read the page -
autokey
IntermediateAutokey cipher
Vigenère without a period: the key self-extends using the plaintext.
Polyalphabetic Read the page -
gronsfeld
IntermediateGronsfeld cipher
Vigenère with a numeric key (0-9). Easier to apply by hand.
Polyalphabetic Read the page -
porta
AdvancedPorta cipher
Thirteen involutive tables. Each key pair picks a distinct mirror.
Polyalphabetic Read the page -
trithemius
IntermediateTrithemius cipher
The first polyalphabetic cipher. Progressive shift, no key.
Polyalphabetic Read the page -
vernam
AdvancedVernam cipher (One-Time Pad)
The only provably unbreakable cipher. Random key, used once.
Polyalphabetic Read the page -
alberti
IntermediateAlberti cipher
The first mechanical cipher. Rotating two-ring disk (1467).
Polyalphabetic Read the page -
bellaso
IntermediateBellaso cipher
Direct ancestor of Vigenère. Polyalphabetic text-key (1553).
Polyalphabetic Read the page -
hill
AdvancedHill cipher
Block cipher by matrix multiplication (1929). Cryptography meets linear algebra.
Polygraphic Read the page -
enigma
AdvancedEnigma machine
The famous WWII German machine. Breaking Enigma founded modern computing.
Polyalphabetic Read the page -
ragbaby
AdvancedRagbaby cipher
Each letter is shifted by its position WITHIN ITS WORD, not in the message.
Polyalphabetic Read the page -
nihilist
IntermediateNihilist cipher
Polybius + additive numeric key. Born among Russian revolutionaries.
Grid Read the page -
slidefair
AdvancedSlidefair cipher
Vigenère that ciphers digrams — each pair is shifted by a key letter.
Polyalphabetic Read the page -
multiplication-vigenere
AdvancedMultiplicative Vigenère
Vigenère where the key multiplies instead of adding. Bijective only for odd keys ≠ 13.
Polyalphabetic Read the page -
adfgx
AdvancedADFGX cipher
Polybius + transposition. Used in 1918, broken by Georges Painvin.
Grid Read the page -
adfgvx
AdvancedADFGVX cipher
Six-letter extension of ADFGX, covering digits 0-9.
Grid Read the page -
columnar
IntermediateColumnar transposition
Text in rows, read in columns ordered by a keyword.
Transposition Read the page -
spiral
IntermediateSpiral cipher
Cleartext drawn as a spiral inside a grid, then read back row by row.
Transposition Read the page -
amsco
AdvancedAMSCO cipher
Alternating 1-2 transposition. Harder to reconstruct.
Transposition Read the page -
rotating-grid
IntermediateRotating grille
A perforated grille rotated 4 times. Visual and tactile.
Transposition Read the page -
playfair
AdvancedPlayfair cipher
Digram cipher on a 5×5 grid. British Army (1854).
Polygraphic Read the page -
four-square
AdvancedFour-square cipher
Digram cipher on four 5×5 grids. Double-keyed.
Polygraphic Read the page -
two-square
IntermediateTwo-square cipher
Digrams on two grids. Simplified Four Square.
Polygraphic Read the page -
three-square
IntermediateThree-square cipher
Three 5×5 grids, two of them keyed. Digram encryption by rectangle rule.
Polygraphic Read the page -
bifid
AdvancedBifid cipher (Delastelle)
Polybius + fractionation. Rows and columns split then recombined.
Grid Read the page -
pollux
IntermediatePollux cipher
Morse + homophony: ., – and / are replaced by multiple digits each.
Polygraphic Read the page -
morbit
IntermediateMorbit cipher
Morse grouped in symbol pairs, each pair becomes a digit 1-9.
Polygraphic Read the page -
trifid
AdvancedTrifid cipher (Delastelle)
3D bifid. 3×3×3 cube, three coordinates per letter.
Grid Read the page -
homophonic
AdvancedHomophonic cipher
Multiple symbols per letter. Aims to flatten frequencies.
Homophonic Read the page -
book-cipher
AdvancedBook cipher
Coordinates in a shared book: page, line, word. Arnold and Beale.
Homophonic Read the page -
grandpre
IntermediateGrandpré cipher
10×10 word grid. Per-letter coordinates — naturally homophonic.
Homophonic Read the page -
tap-code
BeginnerTap code
Polybius transmitted by taps. Used by POWs in Vietnam.
Grid Read the page -
nato
BeginnerNATO phonetic alphabet
Alfa, Bravo, Charlie… One word per letter, for unambiguous spelling.
Code Read the page -
pigpen
BeginnerPigpen cipher (Freemason)
Geometric glyphs from a 3×3 grid + X. Classic masonic code.
Symbols Read the page -
tic-tac-toe
BeginnerTic-Tac-Toe cipher
Pig Pen's playful cousin — 3×3 grid + crosses/circles. Each letter is a graphical fragment.
Symbols Read the page -
templar
BeginnerTemplar cipher
Geometric glyphs from the Templar cross. Seals bills of exchange.
Symbols Read the page -
rosicrucian
BeginnerRosicrucian cipher
Glyphs from a four-arm cross grid. 17th-century esoterica.
Symbols Read the page -
theban
BeginnerTheban alphabet
Curved esoteric alphabet, medieval grimoires and Wicca.
Symbols Read the page -
futhark
BeginnerFuthark runes
Germanic runic alphabet. Scandinavian stones, amulets, inscriptions.
Symbols Read the page -
braille
BeginnerBraille
6 dots in a 2×3 grid. Tactile alphabet, also readable as a cipher.
Signals Read the page -
semaphore
BeginnerFlag semaphore
Two arms × 8 directions = 1 letter. Line-of-sight maritime signalling.
Signals Read the page -
double-transposition
AdvancedDouble transposition
Two columnar transpositions in a row. Held unbreakable for short messages.
Transposition Read the page -
bazeries
AdvancedBazeries cipher
Reversed plaintext + substitution via a spelled-number keyed square.
Polyalphabetic Read the page -
dancing-men
IntermediateDancing Men cipher
Stick figures = mono substitution. Sherlock Holmes, 1903.
Pop culture Read the page -
zodiac
AdvancedZodiac Killer ciphers
Mixed-symbol homophonic from the Zodiac Killer. Z408 in a week, Z340 in 51 years.
Pop culture Read the page -
ave-maria
IntermediateAve Maria cipher (Trithemius)
One Latin word per letter. The ciphertext reads like a prayer.
Code Read the page -
rot-47
BeginnerROT-47
ROT-13 extended to the 94 printable ASCII characters. Fixed shift of 47.
Substitution Read the page -
cisterciens
BeginnerCistercian numerals
One glyph for 1 to 9999, built around a staff. Alphabet encoded by rank.
Numerals Read the page -
xor
IntermediateXOR cipher
Exclusive-OR between plaintext and key. Foundation of modern symmetric crypto.
Modern Read the page -
solitaire
AdvancedSolitaire (Pontifex)
Stream cipher with a 54-card deck. Portable, no computer required.
Polyalphabetic Read the page -
chaocipher
AdvancedChaocipher
Two alphabet discs permuted after every letter. Stayed secret for 90 years.
Polyalphabetic Read the page -
beaufort-variant
IntermediateBeaufort variant (German)
Subtractive Beaufort. Not involutive — easy to mistake for the original.
Polyalphabetic Read the page -
mary-stuart
AdvancedMary Queen of Scots cipher
Homophonic + nomenclator. The cipher that cost Mary Stuart her head.
Homophonic Read the page -
kryptos
AdvancedKryptos (CIA sculpture)
Sculpture-puzzle installed at the CIA. K4 has held since 1990.
Pop culture Read the page -
aurebesh
BeginnerAurebesh (Star Wars)
Star Wars's official alphabet. 1:1 substitution on the Latin alphabet.
Pop culture Read the page -
mayas
BeginnerMayan numerals
Base 20 with dot, bar and shell. One of the earliest positional zeros.
Numerals Read the page -
hexahue
BeginnerHexahue
2×3 mosaic of 6 colours per letter. Mono substitution by colour code.
Symbols Read the page -
ogham
BeginnerOgham (Celtic alphabet)
Notches along a stone's edge. Alphabet of the Irish druids.
Symbols Read the page -
music-notes
BeginnerMusic notes cipher
Each letter → note + octave. Ciphertext that reads as a score.
Code Read the page -
jefferson
AdvancedJefferson cylinder (M-94)
36 rotating discs on an axle. Invented by Jefferson, picked up by the US Army in 1922.
Polyalphabetic Read the page -
vic
AdvancedVIC cipher
Straddling checkerboard + double transposition + numeric key. KGB in the field.
Polygraphic Read the page -
navajo
IntermediateNavajo code talkers
Unwritten Navajo language. The only major WWII code never broken by the enemy.
Code Read the page -
chappe
IntermediateChappe optical telegraph
Articulated-arm tower, 196 positions. Telegraph before electricity.
Signals Read the page -
hieroglyphs
IntermediateEgyptian hieroglyphs
Egyptian pictograms + phonograms. Champollion as the reading key.
Symbols Read the page -
klingon
BeginnerKlingon pIqaD (Star Trek)
Star Trek's official Klingon alphabet. 1:1 substitution, warrior aesthetic.
Pop culture Read the page -
babyloniens
IntermediateBabylonian numerals
Base 60, two signs (wedge + hook). The first positional numeral system.
Numerals Read the page -
tifinagh
BeginnerTifinagh ⵜⵉⴼⵉⵏⴰⵖ
Ancient Berber alphabet still alive. Official in Morocco since 2003.
Symbols Read the page -
phillips
AdvancedPhillips cipher
Eight cyclic 5×5 grids. Each 5-letter block uses the next grid.
Polyalphabetic Read the page -
dorabella
AdvancedDorabella cipher (Elgar)
87 arcs of a circle from Elgar to Dora. Unsolved since 1897.
Pop culture Read the page