Famous Codes & Ciphers

The Enigma machine was used by Nazi Germany to encrypt military communications. Breaking the Enigma code at Bletchley Park is estimated to have shortened the war by at least two years.

Alan Turing led the team at Bletchley Park that cracked the Enigma code. He designed the Bombe machine that could rapidly test possible Enigma settings, and is considered the father of computer science.

Julius Caesar used a simple substitution cipher where each letter was shifted by a fixed number of positions in the alphabet. He typically used a shift of three, so A became D, B became E, and so on.

The Rosetta Stone bears the same decree written in three scripts: Ancient Egyptian hieroglyphs, Demotic script, and Ancient Greek. It was the key to deciphering Egyptian hieroglyphs, primarily by Jean-François Champollion in 1822.

The Navajo Code Talkers used their native language to transmit secret military messages. The Navajo language had no written form and was so complex that the Japanese were never able to crack it.

The Voynich Manuscript is a mysterious illustrated book written in an unknown writing system and language, dated to the early 15th century. Despite intense study by cryptographers, it has never been deciphered.

Morse code was developed by Samuel Morse and Alfred Vail in the 1830s for use with the electric telegraph. It encodes letters and numbers as sequences of dots and dashes (short and long signals).

The scytale was used by the ancient Spartans for military communication. A strip of leather was wrapped around a wooden rod of specific diameter, and the message was written across the wound leather. Only someone with a rod of the same size could read it.

The Zodiac Killer sent four encrypted messages to San Francisco Bay Area newspapers in 1969-1970. The first was cracked within a week, but the Z-340 cipher wasn't solved until 2020, over 50 years later.

Steganography is the practice of hiding secret information within something that appears ordinary, such as invisible ink on a letter, or hidden data within a digital image. Unlike encryption, the goal is to hide the existence of the message itself.

Kryptos is a sculpture by artist Jim Sanborn installed at CIA headquarters in 1990. It contains four encrypted messages. Three have been solved, but the fourth section (K4) remains one of the most famous unsolved codes.

ULTRA was the designation for intelligence obtained by breaking encrypted enemy communications, primarily the German Enigma and Lorenz ciphers. It was one of the most closely guarded secrets of the war.

In cryptography, plaintext refers to the original readable message before encryption. Once encrypted, it becomes 'ciphertext.' The process of converting ciphertext back to plaintext is called decryption.

Bletchley Park was the central site for British codebreaking during World War II. At its peak, about 10,000 people worked there, including mathematicians, linguists, and chess champions, breaking Axis codes.

Mary used a nomenclator cipher (substitution with some code words), but it was cracked by Elizabeth I's spymaster Sir Francis Walsingham's codebreaker. Frequency analysis of the simple substitution elements revealed her treasonous correspondence.