Simple Crypto

Three short films without words, about half a minute each. The cat has a secret for the dog, and the fox sees everything they send.

For a class: full screen, then space to play or pause and the arrow keys to go a scene back or forward.

1 Key exchange

Paint mixing as Diffie-Hellman: mixing is easy, unmixing is not, so the fox saw every pot sent and still cannot make the shared colour.

2 Signature

Only the cat has the stamp (private key), everyone has the see-through pattern (public key), and changing a signed letter breaks its seal.

3 Fingerprint (hash)

A hash: the same letter always gives the same fingerprint, one small change gives a completely different one, and nothing turns a fingerprint back into the letter.