Learn Classical Cryptography
Explore Caesar, Atbash, and Vigenère ciphers to understand the history and principles of cryptography.
Shifts each letter by 13. Self-inverse — applying it twice returns the original.
Education tips
These classical ciphers form the foundation of modern cryptography. Atbash (Hebrew) dates to ~500 BCE; Caesar to ~50 BCE; Vigenère to the 16th century.
Caesar and Atbash are monoalphabetic — each letter always maps to the same output. Vigenère is polyalphabetic — the same letter maps to different outputs depending on position.
The Vigenère cipher was called "le chiffre indéchiffrable" (the indecipherable cipher) for centuries until Charles Babbage cracked it in 1854.
Try encoding the same message with all four ciphers and compare. The Vigenère output looks most random because the key varies — this demonstrates why key length matters.
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