1. A method for transmitting and receiving a digital message having N digits, each of said N digits having any one of M values, in a system wherein each of said M values k corresponds with a k th -chaotic signal generator having chaotic characteristic value associating with a chaotic algorithm; and is transmitted within a bit period including the steps of: selecting the corresponding k th -chaotic signal generator; generating a chaotic signal by the corresponding k th -chaotic signal generator; and receiving the chaotic signal at a receiver storing the chaotic characteristic values of all of the chaotic signal generators and a demodulating algorithm, and demodulating the chaotic signal to generate the transmitted value k.