Patent ID: 7839946

Claim:
A data transmitting apparatus for encrypting information data by using predetermined key information and performing secret communication with a receiving apparatus, the data transmitting apparatus comprising: a multi-level code generation section for generating, based on the predetermined key information, a multi-level code sequence in which a signal level changes so as to be approximately random numbers; a multi-level code conversion section for converting the multi-level code sequence into a converted multi-level code sequence; a multi-level processing section for combining the information data and the converted multi-level code sequence and generating a multi-level signal having a plurality of levels each corresponding to a combination of the information data and the converted multi-level code sequence; and a modulator section for modulating the multi-level signal in a predetermined modulation method, and outputting a modulated signal, wherein the multi-level code conversion section irreversibly converts the multi-level code sequence such that the converted multi-level code sequence does not become a mapping of the multi-level code sequence.