Abstract: A cryptation system for information transmitted through packet switching networks masks the digital information data by combining it at the transmitting station with digital data of a certain cryptation code before transmitting the so-encrypted data through the network. The system also performs an inverse decrypting processing at the receiving station using the same code. The system generates at a transmitting station and at a receiving station, starting from a given pair of password codes or user key, a certain discrete chaotic model or map of the pair of codes or key, producing dynamically updated pairs of values of codes or keys every certain number of processing steps of the chaotic map. The data to be transmitted is masked by way of a logic combination with the current dynamically updated keys at the transmitting station.