You can try the first discovery and the 3D controls now. Stella unlocks every stage.
Public-key Cryptography: Sharing a Secret Without Sending the Key
Start from a key copied in transit and discover, through a remainder clock, colour-mixing key exchange, a cutaway padlock, a man in the middle, your browser’s one round trip and the lattices beyond quantum, how two strangers make a secret.
Keys get copied on the way
Symmetric encryption, where the same key locks and unlocks, is fast and good at protecting the message itself. But first that key has to reach the other desk. Along the channel sits Eve’s tap. Send the key and watch: the key that reaches Bob is flawless, as if nothing happened. Yet in Eve’s tray lies a copy of exactly the same shape. The receiver cannot tell that a copy was made. This is the key-distribution problem, unsolved since the Enigma era.
Send the key and watch a copy peel away at Eve’s tap. Then send letters and see Eve open them one by one with her copy.
Everything that crosses the channel is visible to Eve.
- The symmetric key (a copy)17Newly seen
- Letters closed with that keyNewly seen
You can try the first discovery and the 3D controls now. Stella unlocks every stage.