A basic cryptography system consists of a message X ☐ and a key K ⬤ such that the key covers the message in modulo ⊕.
Now, for Bob to receive information from Alice, Bob must have the key to decrypt the information.
But a 3rd person Eve (eavesdrop ۞) may try to get information from Alice
However a cypher text is placed to prevent Eve from getting the information.
Hence, for symbols x0, x1, x2, …, x10 if each symbol is represented by binary digits with each symbol having its own key and its own cypher text, for example
This continuously chosen keys so that none of the binary digits repeat is called a 'one-time pad'.❷
Error rate (p:3) ➽