Would a symmetric cipher with a keylength a big as the data length be information theoretically secure?
One-Time-Pad is information theoretically secure as long as the random number stream is evenly long or longer than the data stream it encrypts, for a "decyphered" message could have been any message ...
These terms are confusing me. One time pad is when you use one key for one message. That is what One time key is. Secondly, what is the connection of many time key, can i use one time pad many ...