All Cipher & Code Tools

Shift each letter by N positions in the alphabet

Julius Caesar · ~58 BC

Caesar cipher with fixed shift of 13 — encode and decode are identical

Usenet community · 1980s

Reverses the alphabet: A↔Z, B↔Y, etc.

Hebrew scribes · ~600 BC

E(x) = (ax + b) mod 26 — combines multiplication and addition

Polyalphabetic substitution using a repeating keyword

Giovan Battista Bellaso · 1553

Encrypts letter pairs using a 5x5 keyword grid

Charles Wheatstone · 1854

Writes text in a zigzag pattern across N rails then reads each rail

Arranges text in rows under a keyword and reads columns in alphabetical order

Replaces each letter with another using a 26-letter mapping key

Encodes each letter as a 5-character sequence of A and B

Francis Bacon · 1605

Encodes letters as sequences of dots and dashes

Samuel Morse · 1837

Encodes binary data using 64 printable ASCII characters

Converts letters to NATO phonetic words (Alpha, Bravo, Charlie…)

Converts text to and from 8-bit binary representation

Converts text to and from base-16 hexadecimal values

Converts text to and from decimal ASCII character codes

A=1, B=2, C=3, ..., Z=26 — the simplest number cipher

Converts text to Unicode Braille patterns (Grade 1)

Encrypts letters using geometric symbols from a grid pattern

18th century