Cryptography, Elliptic Curves, Rsa, Blockchain, Bitcoin.
does just that. By shifting the letters some number of places X, the words in your message become unreadable [Fig.1]. Once X is communicated, the jumble of letters can be unshifted to decrypt the message. Fig. 1 A Cesar Cipher where the shift is 3. “E” will then take the place of “B”, “F” for “C”