Data transmission apparatus, data receiving apparatus and method executed thereof

Abstract

A data transmitting apparatus 1101 generates, by using predetermined first key information 11; and information data 10, a multi-level signal 13 in which a signal level changes so as to be approximately random numbers, and converts the multi-level signal 13 into a modulated signal 14, in a predetermined modulation method and transfer the same. A data receiving apparatus 1201 demodulates the modulated signal 14 so as to be converted into a multi-level signal 15, and reproduces information data 18 from the multi-level signal 15, using second key information 16 which has the same content as first key information 11 used by the data transmitting apparatus 1101.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a configuration of data communication apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating waveforms of a transmission signal of the data communication apparatus according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating names of the waveforms of the transmission signal of the data communication apparatus according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating quality of the transmission signal of the data communication apparatus according to the first embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of the data communication apparatus according to the second embodiment of the present invention.

FIG. 6 is a flowchart illustrating a method executed by a data transmitting apparatus 1102 of FIG. 5.

FIG. 7 is a flowchart illustrating a method executed by a data receiving apparatus 1202 of FIG. 5.

FIG. 8 is a diagram showing an action (legitimate communication) of the data communication apparatus according to the second embodiment of the present invention.

FIG. 9 is a diagram showing an action (eavesdropping) of the data communication apparatus according to the second embodiment of the present invention.

FIG. 10 is a block diagram showing a configuration of the data communication apparatus according to the third embodiment of the present invention.

FIG. 11 is a block diagram showing a configuration of a conventional data communication apparatus.

Claims

1. A data transmitting apparatus for performing cipher communication, the data transmitting apparatus comprising: a multi-level code generation section for generating, by using predetermined key information, a multi-level code sequence in which a signal level changes so as to be approximately random numbers;a combining section for combining accompanying data to the multi-level code sequence with predetermined frequency and generating a combined multi-level signal;an error-correction encoding section for adding an error-correction code to information data, in accordance with predetermined error correction encoding processing, and outputting error-correction encoded information data;a multi-level processing section for combining the combined multi-level signal and the error-correction encoded information data in accordance with predetermined processing, and generating a multi-level signal having a level uniquely corresponding to a combination of levels of both combined signals represented by the combined multi-level signal and the error-correction encoded information data; anda modulator section for generating a modulated signal, in a predetermined modulation method, based on the multi-level signal.

2. The data transmitting apparatus according to claim 1, wherein the accompanying data is a synchronous signal which is synchronizing with the information data.

3. The data transmitting apparatus according to claim 1, wherein the accompanying data is an N frequency-dividing clock of the information data.

4. The data transmitting apparatus according to claim 1, wherein the accompanying data has a predetermined code-synchronous pattern.

5. A data receiving apparatus for performing cipher communication, the data receiving apparatus comprising: a demodulator section for demodulating a modulated signal generated, in a predetermined modulation method, based on error-correction encoded information data and a combined multi-level signal having accompanying data included therein, and outputting a multi-level signal obtained by the demodulation;a multi-level code generation section for generating, by using predetermined key information, a multi-level code sequence in which a signal level changes so as to be approximately random numbers;a multi-level identification section for identifying the multi-level signal in accordance with the multi-level code sequence, and outputting data which is identified and reproduced; andan error-correction decoding section for detecting, from the data reproduced by the multi-level identification section, difference between the combined multi-level signal and the multi-level code sequence, in accordance with predetermined error-correction decoding processing, and outputting a result of the detection as the accompanying data, and also outputting information which is error-correction decoded as the information data.

6. A data receiving apparatus for performing cipher communication, the data receiving apparatus comprising: a demodulator section for demodulating a modulated signal, in a predetermined modulation method, generated based on error-correction encoded information data and a combined multi-level signal having accompanying data included therein, and outputting a multi-level signal obtained by the demodulation;a multi-level code generation section for generating, by using predetermined key information and a synchronous signal, a multi-level code sequence in which a signal level changes so as to be approximately random numbers;a multi-level identification section for identifying the multi-level signal in accordance with the multi-level code sequence, and outputting data which is identified and reproduced;an error-correction decoding section for detecting, from the data reproduced by the multi-level identification section, difference between the combined multi-level signal and the multi-level code sequence, in accordance with predetermined error-correction decoding processing, and outputting a result of the detection as the accompanying data, and also outputting information which is error-correction decoded as the information data; anda synchronous extraction section for inputting the accompanying data, extracting the synchronous signal synchronizing with the accompanying data in accordance with a predetermined procedure, and outputting the extracted synchronous signal to the multi-level code generation section.

7. The data receiving apparatus according to claim 6, wherein the synchronous extraction section further inputs a predetermined code-synchronous pattern, and extracts the synchronous signal synchronizing with the accompanying data in accordance with a predetermined procedure.

8. A data transmitting method for performing cipher communication, the data transmitting method comprising: a step of generating, by using predetermined key information, a multi-level code sequence in which a signal level changes so as to be approximately random numbers;a step of combining accompanying data to the multi-level code sequence with predetermined frequency and generating a combined multi-level signal;a step of adding an error-correction code to information data, in accordance with predetermined error-correction encoding processing, and outputting the error-correction encoded information data;a step of combining the combined multi-level signal and the error-correction encoded information data, in accordance with predetermined processing, and generating a multi-level signal having a level uniquely corresponding to a combination of levels of both signals represented by the combined multi-level signal and the error-correction encoded information data; anda step of generating a modulated signal, in a predetermined modulation method, based on the multi-level signal.

9. A data receiving method for performing cipher communication, the data receiving method comprising: a step of demodulating a modulated signal, in a predetermined modulation method, generated based on error-correction encoded information data and a combined multi-level signal having accompanying data included therein, and outputting a multi-level signal obtained by the demodulation;a step of generating, by using predetermined key information, a multi-level code sequence in which a signal level changes so as to be approximate random numbers;a step of identifying the multi-level signal based on the multi-level code sequence and outputting data which is identified and reproduced; anda step of detecting, from the data reproduced by the multi-level identification section, difference between the combined multi-level signal and the multi-level code sequence, in accordance with predetermined error-correction decoding processing and outputting a result of the detection as the accompanying data, and also outputting information which is error-correction decoded as the information data.

10. A data receiving method for performing cipher communication, the data receiving method comprising: a step of demodulating a modulated signal, in a predetermined modulation method, generated based on error-correction encoded information data and a combined multi-level signal having accompanying data included therein, and outputting a multi-level signal obtained by the demodulation;a step of generating, by using predetermined key information and a synchronous signal, a multi-level code sequence in which a signal level changes so as to be approximate random numbers;a step of identifying the multi-level signal in accordance with the multi-level code sequence and outputting data which is identified and reproduced;a step of detecting, from the data reproduced by the multi-level identification section, difference between the combined multi-level signal and the multi-level code sequence, in accordance with predetermined error-correction decoding processing, and outputting a result of the detection as the accompanying data, and also outputting information which is error-correction decoded as the information data; anda step of inputting the accompanying data, extracting the synchronous signal synchronizing with the accompanying data in accordance with a predetermined procedure, and outputting the extracted synchronous signal to the multi-level code generation section.