Data transmitting apparatus and data receiving apparatus

Abstract

A data communication apparatus 1 for safely transmitting information data 11 and additional information 14 is provided. In a data transmitting apparatus 101, a random number sequence generating part 111 generates a random number sequence 12 from key information 11. A diffusing part 112 generates diffused additional information 14 by time-diffusing additional information 14. A multi-level signal generating part 113 generates a multi-level signal 16 the signal level of which varies substantially like a random number, based on information data 13, the random number sequence 12, and the diffused additional information 14. In a data receiving apparatus 201, a random number sequence generating part 211 generates a random number sequence 22 from key information 21. An information data decoding part 213 decodes information data 23 and additional information 24 based on the random number sequence 22.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an example of the structure of a communication apparatus 1 according to a first embodiment of the present invention;

FIG. 2 is a block diagram showing an example of the detailed structure of a data transmitting apparatus 101 according to the first embodiment of the present invention;

FIG. 3 is a schematic view showing an example of the signals generated in each part of the data transmitting apparatus 101 according to the first embodiment of the present invention;

FIG. 4 is a schematic view showing an example of the signals generated in each part of a data receiving apparatus 201 according to the first embodiment of the present invention;

FIG. 5 is a block diagram showing an example of the structure of a data transmitting apparatus 102 according to a second embodiment of the present invention;

FIG. 6 is a block diagram showing an example of the detailed structure of the data transmitting apparatus 102 according to the second embodiment of the present invention;

FIG. 7 is a block diagram showing an example of the structure of a data receiving apparatus 202 according to the second embodiment of the present invention;

FIG. 8 is a block diagram showing an example of the structure of a data transmitting apparatus 103 according to a third embodiment of the present invention;

FIG. 9 is a block diagram showing an example of the structure of a data transmitting apparatus 103a according to the third embodiment of the present invention;

FIG. 10 is a block diagram showing an example of the structure of the conventional data communication apparatus 9 using the Y-00 protocol;

FIG. 11 is a view showing the signal format used in the Y-00 protocol; and

FIG. 12 is a schematic view for explaining the signals configuration used in the conventional data communication apparatus 9.

Claims

1. A data transmitting apparatus that encrypts information data by use of predetermined key information, and performs secret communication with a receiving apparatus, the data transmitting apparatus comprising: a random number sequence generating part that generates a random number sequence based on the predetermined key information;a diffusing part that generates diffused additional information by time-diffusing predetermined additional information based on the random number sequence; anda multi-level signal modulating part that generates a signal, a signal level of which varies substantially like a random number, based on the information data, the random number sequence, and the diffused additional information, performs predetermined modulation processing on the generated signal, and outputs the processed signal as a modulated signal.

2. The data transmitting apparatus according to claim 1, wherein the multi-level signal modulating part includes: a multi-level signal generating part that generates a multi-level signal, a signal level of which varies substantially like a random number, based on the information data, the random number sequence, and the diffused additional information; anda modulating part that performs the predetermined modulation processing on the multi-level signal, and outputs the modulated signal.

3. The data transmitting apparatus according to claim 2, wherein the multi-level signal generating part has: a scrambling part that generates scrambled information data a signal level of which is multi-level-scrambled, based on the information data and the random number sequence; andan additional information superimposing part that generates the multi-level signal by superimposing the diffused additional information on the scrambled information data.

4. The data transmitting apparatus according to claim 2, wherein the multi-level signal generating part generates the multi-level signal by converting a value obtained by digitally adding the information data, the random number sequence, and the diffused additional information by a predetermined method, into an analog value.

5. The data transmitting apparatus according to claim 2, wherein the predetermined key information includes at least first key information and second key information, the random number sequence generating part includes:a first random number sequence generating part that generates a first random number sequence based on the first key information; anda second random number sequence generating part that generates a second random number sequence based on the second key information,the diffusing part generates the diffused additional information by time-diffusing the additional information based on the second random number sequence, andthe multi-level signal generating part generates the multi-level signal based on the information data, the first random number sequence, and the diffused additional information.

6. The data transmitting apparatus according to claim 1, wherein the multi-level signal modulating part includes: a scrambling part that generates scrambled information data a signal level of which is multi-level-scrambled, based on the information data and the random number sequence;a first modulating part that generates a first modulated signal by performing predetermined modulation processing on the scrambled information data;a second modulating part that generates a second modulated signal by performing predetermined modulation processing on the diffused additional information; andan adding part that adds the first modulated signal and the second modulated signal, and outputs a signal resulting from the addition, as the modulated signal.

7. The data transmitting apparatus according to claim 6, wherein the predetermined key information includes at least first key information and second key information, the random number sequence generating part includes:a first random number sequence generating part that generates a first random number sequence based on the first key information; anda second random number sequence generating part that generates a second random number sequence based on the second key information,the scrambling part generates scrambled information data a signal level of which is multi-level-scrambled, based on the information data and the first random number sequence, andthe diffusing part generates the diffused additional information by time-diffusing the additional information based on the second random number sequence.

8. The data transmitting apparatus according to claim 1, wherein a signal power of the diffused additional information is lower than a noise power included in a signal band corresponding to a chip rate of the diffused additional information.

9. The data transmitting apparatus according to claim 3, wherein a signal level of the diffused additional information is adjusted so that a signal level of the multi-level signal is any of signal levels that the scrambled information data can take.

10. The data transmitting apparatus according to claim 3, wherein a signal level of the diffused additional information is an integral multiple of a distance between adjoining signal points of the scrambled information data.

11. The data transmitting apparatus according to claim 2, wherein a chip rate of the diffused additional information is an integral multiple of a symbol rate of the multi-level signal.

12. The data transmitting apparatus according to claim 6, wherein a chip rate of the diffused additional information is an integral multiple of a symbol rate of the scrambled information data.

13. The data transmitting apparatus according to claim 1, wherein the random number sequence inputted to the diffusing part is used for the time diffusion of the additional information after a predetermined section of the random number sequence is substantially periodically thinned.

14. A data receiving apparatus that receives information data encrypted by use of predetermined key information, and performs secret communication with a transmitting apparatus, the data receiving apparatus comprising: a random number sequence generating part that generates a random number sequence based on the predetermined key information;a demodulating part that performs predetermined demodulation processing on a modulated signal received from the transmitting apparatus, and outputs a multi-level signal a signal level of which varies substantially like a random number;a separating part that separates the multi-level signal into two paths;an information data decoding part that decodes the information data from the multi-level signal separated into one of the paths, based on the random number sequence;a scrambling part that generates scrambled information data a signal level of which is multi-level-scrambled, based on the information data and the random number sequence;a scrambled information data removing part that removes the scrambled information data from the multi-level signal separated into the other of the paths to thereby output diffused additional information obtained by time-diffusing predetermined additional information based on the random number sequence; andan inversely diffusing part that decodes the additional information by performing inverse diffusion processing on the diffused additional information by use of the random number sequence.

15. The data receiving apparatus according to claim 14, wherein the predetermined key information includes at least first key information and second key information, the random number sequence generating part includes:a first random number sequence generating part that generates a first random number sequence based on the first key information; anda second random number sequence generating part that generates a second random number sequence based on the second key information,the information data decoding part decodes the information data from the multi-level signal separated into one of the paths, based on the first random number sequence,the scrambling part generates the scrambled information data the signal level of which is multi-level-scrambled, based on the information data and the first random number sequence,the scrambled information data removing part removes the scrambled information data from the multi-level signal separated into the other of the paths to thereby output diffused additional information obtained by time-diffusing predetermined additional information based on the second random number sequence; andthe inversely diffusing part decodes the additional information by performing inverse diffusion on the diffused additional information by use of the second random number sequence.

16. The data receiving apparatus according to claim 14, wherein a signal power of the diffused additional information is lower than a noise power included in a signal band corresponding to a chip rate of the diffused additional information.

17. The data receiving apparatus according to claim 14, wherein a signal level of the diffused additional information is adjusted so that a signal level of the multi-level signal is any of signal levels that the scrambled information data can take.

18. The data receiving apparatus according to claim 14, wherein a signal level of the diffused additional information is an integral multiple of a distance between adjoining signal points of the scrambled information data.

19. The data receiving apparatus according to claim 14, wherein a chip rate of the diffused additional information is an integral multiple of a symbol rate of the multi-level signal.

20. The data receiving apparatus according to claim 14, wherein a chip rate of the diffused additional information is an integral multiple of a symbol rate of the scrambled information data.

21. The data receiving apparatus according to claim 14, wherein the random number sequence inputted to the inversely diffusing part is used for the inverse diffusion processing of the diffused additional information after a predetermined section of the random number sequence is substantially periodically thinned.

22. A data transmitting method in which a data transmitting apparatus encrypts information data by use of predetermined key information, and performs secret communication with a receiving apparatus, the data transmitting method comprising: a random number sequence generating step of generating a random number sequence based on the predetermined key information;a diffusing step of generating diffused additional information by time-diffusing predetermined additional information based on the random number sequence; anda multi-level signal modulating step of generating a signal, a signal level of which varies substantially like a random number, based on the information data, the random number sequence, and the diffused additional information, performing predetermined modulation processing on the generated signal, and outputting the processed signal as a modulated signal.

23. A data receiving method in which a data receiving apparatus receives information data encrypted by use of predetermined key information, and performs secret communication with a transmitting apparatus, the data receiving method comprising: a random number sequence generating step of generating a random number sequence based on the predetermined key information;a demodulating step of performing predetermined demodulation processing on a modulated signal received from the transmitting apparatus, and outputting a multi-level signal a signal level of which varies substantially like a random number;a separating part of separating the multi-level signal into two paths;an information data decoding step of decoding the information data from the multi-level signal separated into one of the paths, based on the random number sequence;a step of generating scrambled information data a signal level of which is multi-level-scrambled, based on the information data and the random number sequence;a scrambled information data removing step of removing the scrambled information data from the multi-level signal separated into the other of the paths to thereby output diffused additional information obtained by time-diffusing predetermined additional information based on the random number sequence; andan inversely diffusing step of decoding the additional information by performing inverse diffusion processing on the diffused additional information by use of the random number sequence.