I would like to know what is the real purpose of using a modulus in the equivalent of a Vernam cipher: Data $d$, large number $M$ Assume the key length is λ bits. Then M could be 2^λ. k is picked ...
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 ...