Gambling with Secrets: Part 4/8 (Private Key Cryptography)

Eve the codebreaker intercepts encrypted messages and calculates letter frequencies, discovering that repeating keyword patterns create detectable statistical fingerprints despite the flatter distribution compared to simple substitution ciphers.

Codebreakers exploit the fundamental principle that any repetitive pattern in encryption methods creates differential frequency distributions that leak information about the underlying plaintext structure.

Comparing Caesar cipher’s 26 possible encryptions of Alice’s name against one-time pad’s 26 to the fifth power possibilities—nearly 12 million encryptions—visualizes how random keys create astronomical outcome spaces.

Alice generates a list of truly random shift values as long as her message by rolling a 26-sided die, shares this random key with Bob in advance, then uses each random shift exactly once to encrypt one message letter.

One-time pad encryption achieves perfect secrecy through two critical properties—shifts never fall into repetitive patterns and the encrypted message exhibits perfectly uniform frequency distribution across all letters.

Alice and Bob share a secret shift word that Alice converts into numbers representing alphabet positions, using these numbers as variable shift amounts to encrypt each message letter before sending it openly to Bob for decryption.