Computer Science · Cryptography

Cryptography & The Enigma

From ancient Rome to the Allied codebreakers at Bletchley Park, encryption has shaped history. Step through three eras of cryptography: shift ciphers, the Enigma machine, and modern RSA public-key encryption.

Three Eras

Caesar Cipher — shift every letter by a fixed amount
Enigma Machine — polyalphabetic substitution with rotors
RSA — public-key encryption using prime factorization
Each era solved flaws in the previous generation

Caesar Cipher — Shift Cipher

Shift: 3

Ciphertext Output

Enigma Machine Simulator

Rotor I A

Rotor II A

Rotor III A

Decrypted / Encrypted Output

RSA Key Exchange

1. Key Generation

Pick two prime numbers p and q. (e.g. 11, 13, 17, 23).

Modulus (N = p×q): —

Totient (φ): —

Public Exponent (e): —

Private Key (d): —

2. Encrypt & Decrypt

Enter a numeric message (smaller than N). The math uses C = M^e mod N to encrypt.

Ciphertext (Intercepted over network):

—

Decrypted Message:

—

Julius Caesar (58 BC)

Used a simple shift cipher to communicate with his generals. Effective against illiterate enemies, trivially broken by frequency analysis.

The Enigma Machine (1930s)

Germany's electro-mechanical cipher used rotating wheels to create a different substitution alphabet for every keypress — 158 quintillion possible settings.

Bletchley Park (1939–45)

Alan Turing and the codebreakers built the Bombe machine to exploit a fatal Enigma flaw: no letter could encrypt to itself. This shortened WWII by an estimated two years.

RSA (1977)

Rivest, Shamir, and Adleman published the first practical public-key system. Security rests on the difficulty of factoring large numbers — the same math behind every HTTPS connection today.