How Ciphers Work
From pen-and-paper codes to the mathematics behind modern security
Every Classical Cipher Teaches Modern Cryptography
The same ideas that protected Caesar's dispatches now protect your bank account — just with stronger mathematics. Each exhibit includes a "What It Teaches" section connecting the classical failure to the modern solution.
Caesar and monoalphabetic ciphers evolved into AES S-boxes — non-linear substitution tables designed specifically to defeat frequency analysis.
Vigenère's repeating keyword became ChaCha20's continuous random keystream — the same XOR operation, with a key that never repeats.
Rail Fence and columnar transposition became AES ShiftRows — ensuring every output bit depends on every input bit.
Enigma's rotating alphabets became AES rounds — multiple iterations of substitution and permutation to achieve confusion and diffusion.
Breaking the Lorenz cipher required Colossus — the world's first programmable electronic computer. Cryptanalysis built computing.
Shannon proved the OTP is information-theoretically secure. Every modern cipher aims for computational security — as close to perfect as practical key management allows.
Explore by Topic
Modern Cryptography
How classical failures became AES, RSA, and post-quantum security. The full evolution from pen-and-paper to computational security.
Cryptanalysis Techniques
Frequency analysis, Kasiski examination, and index of coincidence — the tools that broke every classical cipher.
Glossary
Definitions of every cryptographic term used in the museum — from plaintext to key derivation function.
Cipher Comparison
Side-by-side analysis of every cipher in the museum — type, era, security status, and key properties.
Start with the Caesar Cipher
The simplest cipher in history is the best place to begin. Learn how Julius Caesar encoded messages — then see how the same idea powers modern encryption.
Start with Caesar →