code: Quick Facts

Written and fact-checked by

The Information Architects of Encyclopaedia Britannica

Photos

Infographic about Navajo Code Talkers in World War II, featuring statistics on the number of participants, code examples, a map showing other tribes involved, and facts about the code's speed and unbreakable status. Text highlights their key role in the U.S. victory over Japan and notes that over 800 messages were sent error-free during the battle of Iwo Jima.

Jade cipher machine

Purple cipher machine

Frequency distribution for plaintext and its repeated-key Vigenère cipher

Diagram explaining the German ADFGVX cipher from World War I, showing a biliteral substitution array, examples of plaintext and intermediate ciphertext in red, and a transposition matrix with final ciphertext in blue.

DES flow diagram

A Vigenere cipher table displays the alphabet in both the top row and left column, with rows shifted to create a grid for encryption and decryption. Highlighted letters illustrate how to use the table. An explanation and example using the words cipher, key, and plaintext appears to the right.

See All Images →

Topics

Navajo Code Talkers Infographic Morse Code convolutional code coding system block code repetition code encoding Baudot Code ASCII Today in History—May 2: A War Changed by the Blink of an Eye cryptographic key

Dig Deeper: More Articles That Discuss This Topic

cryptology: The fundamentals of codes, ciphers, and authentication

Key People

default image

Agnes Meyer Driscoll

American cryptologist

A botanical illustration from the Voynich manuscript, a codex, scientific or magical text in an unidentified language, in cipher; end of the 15th or during the 16th century (?).

Codes, Secrets, and Ciphers Quiz