It's inconvenient for any amount of data, because it essentially begs the question; if you can securely transmit N bytes of key pad to a counterparty, just use that mechanism to transmit N bytes of plaintext instead.
It's inconvenient for any amount of data, because it essentially begs the question; if you can securely transmit N bytes of key pad to a counterparty, just use that mechanism to transmit N bytes of plaintext instead.
It has the advantage that the key can be sent before the message is known. Think military battlefield. Your commander goes out to war with a CD, and then he can transmit messages like "we encountered the enemy". It would do no good to transmit "we encountered the enemy" before the war started.