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Semicolony ELI5 · comic

Public-key crypto.

A padlock anyone can snap shut, but only you hold the key to open.

  1. But how do we swap the key?
    one shared key — but how?
    1

    Old codes used one shared key — and two strangers can’t agree on it without someone overhearing.

  2. Take a padlock. Keep the key.
    public padlock private key never share
    2

    A key pair fixes that: a public key you hand to everyone, a private key you never let go of.

  3. Sealed it with your padlock.
    secret snapped shut
    3

    Anyone can snap your public padlock shut on a message — no password agreed first.

  4. And only I can open it.
    secret locked out
    4

    Only your private key opens it. The secret lands safely, the eavesdropper gets nothing.

  5. My signature — verify away.
    message private key
    5

    Run it backwards: lock with your private key and anyone can check it with the public one.

  6. Signed, and untampered.
    from Bit genuine, and untouched
    6

    Since only you hold the private key, a passing check proves the message is really from you.

One pair of linked keys, used two clever ways: receiving secrets, and proving they came from you.
Semicolony semicolony.dev/eli5/public-key-crypto/comic
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