The perfect encryption algorithm

- Wouldn't it be nice if someone would invent…a perfect encryption algorithm that was unbreakable?…Well, someone already did.…And it was more than 100 years ago.…The one-time pad, invented by a telegraph expert in 1882,…is an example of an unbreakable cipher.…Using the one-time pad is fairly straightforward.…The sender and receiver each have a copy of identical pads…containing strings of random letters.…The pad must be as long as the total of the characters…of all of the messages that they will exchange.…

Here's an example of what one page…in the one-time pad might look like.…The sender writes the characters of the message…in plaintext on the pad.…If my message is the word secret,…I would simply write that out across the top of the pad.…The sender then adds together the characters of the message,…and the characters of the key,…treating them as numbers.…A is the first letter of the alphabet,…so think of it as the number one.…B is the number two, and so on.…If we encrypt the first letter, S, here,…we do it by adding the first letter of the key, which is A.…