Encryption, a lock with a key

New idea

A fingerprint can't carry a message

A hash is one-way, perfect for passwords. But when you send your friend a chat message, they need to read it. A fingerprint of the message would be useless to them.

For that we need encryption, a two-way lock. With a key, readable text (plaintext) becomes scrambled text (ciphertext), and the right key turns it back.

So: hashing has no way back, ever. Encryption has a way back, but only for whoever holds the key.