JPS6315544A - Method for transmitting information in confidential way by radio communication - Google Patents

Abstract

PURPOSE:To form an information transmission system inexpensively by applying exclusive OR to information and a cipher decoding pattern, converting them into a digital signal, adding a cipher code corresponding to said decoding and sending the result as a radio wave in sending the information in radio to a specific party. CONSTITUTION:When a cipher code MC is set in advance and inputted to the RAM control circuit of a block 6, the RAM control circuit reads the cipher decoding pattern MP corresponding to the cipher code MC from the random access memory RAM of a block 5, the pattern MP is ORed with a digitized voice data DV exclusively by the block 4 to be enciphered. Thus, even when the same cipher code is used, the decoding of the cipher data is made difficult by the periorical change of the cipher pattern even if the same cipher data is used.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention encrypts the information in a transmitting device when transmitting arbitrary information to a specific person by wireless communication means, and the receiving device encrypts the information. This invention relates to a method for secretly transmitting information by decoding the information and restoring the original information.

(Prior Art) Conventionally, when transmitting information to a specific person using wireless communication means, various types of signals are added to the signal waves transmitted from the transmitter in order to ensure that the information can only be used by authorized persons. A method was adopted in which the received signal waves were scrambled and the received signal waves were descrambled by the receiving device to reproduce the original information.

(Problems to be Solved by the Invention) In the case of the above-mentioned method for secretly transmitting information using conventional wireless communication means, if a scrambling circuit for scrambling the original information is fixed, the information can be easily decoded by a third party. To prevent this, if encryption-based scrambling is enabled, the circuit for this will become complicated and the system price will increase.

Furthermore, when the original information is scrambled and transmitted wirelessly, it is transmitted as an analog signal, which causes the problem that signal deterioration may occur on the receiving device side, and it is not easy to change the Meigetsu decoding key. There was a problem.

Therefore, in the present invention, when transmitting information from a transmission device to a specific person by line, the information and a decryption pattern are exclusively ORed to convert into a digital signal, and a cryptographic code roughly corresponding to the decryption pattern is generated. The conventional problem is solved by generating an encrypted digital signal added to the digital signal and wirelessly transmitting it to a receiving device on the specific person's side, and by making it possible to easily change a decryption pattern corresponding to the encrypted code. This is a technical issue.

(Means for Solving the Problems) The technical means for solving the above problems is to provide a method for secretly transmitting information by wireless communication to a transmission device that transmits information to a specific person by wireless communication means, After generating a digital signal by exclusive ORing a deciphering pattern arbitrarily selected from a storage unit in which a plurality of deciphering patterns that can be changed at will is stored, Digital Shintan The encrypted code signal corresponding to the decryption pattern is multiplexed, the encrypted digital signal obtained by multiplexing is modulated and power amplified, and then emitted from the transmitting antenna to be received by the receiving device on the specified & side. Demodulating the received encrypted digital signal, recognizing the encryption code in the demodulated encrypted digital signal, and storing a Meigetsu decoding pattern corresponding to the plurality of decryption patterns stored in the transmission device. A decryption pattern corresponding to the encryption code transmitted in advance to the reception branch by any means is read from the storage section of the receiving device, and the read decryption pattern and the information part in the demodulated encrypted digital signal are excluded. The original information is restored by performing a logical sum and correcting errors in the information part.

(Example) Next, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an electrical circuit block of a transmitting device in an information transmission system for transmitting audio data, and FIG. 2 shows an electrical circuit block of a receiving device. Also, the third
The figure shows an example of a frame configuration for every millisecond when audio data that has been sampled, encrypted, and encrypted at a predetermined sampling frequency is transmitted.

In Figure 1, information to be transmitted to a specific person is voice data, and this analog voice data is block 1.
After passing through the low-pass filter LPF, it is sampled and filtered at a rimbling frequency of, for example, 48 KHz in block 2, and in block 3, for example, switching between stereo and monaural, encryption code confirmation request data, or audio data switching is performed. etc., and is converted into a digital signal with a control code CC added thereto. The audio data DV converted into a digital signal in block 3 is encrypted in block 4. This encryption means is performed as follows. That is, when a cryptographic code MC is set in advance and this cryptographic code MC is input to the RAM L control circuit of block 6, the RAM control circuit t and the random access memory RAM of block 5 in which a plurality of decryption patterns are stored. A decryption pattern MP corresponding to the set encryption code MC is read out from the decryption pattern MP, and the read decryption pattern MP and the digital signalized audio data DV are exclusive ORed in block 4 and encrypted. Data OA encrypted in block 4
is multiplexed with the encryption code MC in block 7, and further added with a control code CC, a frame synchronization signal SYS, an error correction 'ifN code EC3, etc. as shown in FIG. 3, and interleaved in block 8. A frame is constructed.

The 7j framed digital signal gFD, which is interleaved in block 8 and configured in units of frames, is scrambled in block 9. At this time, a pseudo signal (PN signal) is generated from block 10, and the pseudo signal is imposed on the framed digital signal FD.

The scrambled framed digital signal FDS in block 9 is subjected to block 111: 4-phase DPSK modulation, ie 4-phase differential phase shift key ink modulation. On this occasion,
The subcarriers generated in block 12
PSK modulated. 4-phase DPSK in block 11
The modulated signal is combined with other audio data in frame 13, FM modulated in frame 14, power amplified, and transmitted from antenna 15 as a radio wave.

The encrypted digital signal corresponding to audio information transmitted as a radio wave from the antenna 15 is received by the antenna 20 of the receiving device shown in FIG.

In FIG. 2, the encrypted digital signal received by the antenna 20 is tuned in block 21, and then the demodulation of FMK1 modulation assigned to block 14 of the transmitting device is performed in block 22, and At 23, the four-phase DPSK modulation in the block 11 is demodulated. Since the received data that has been successfully demodulated by 4-phase DPSK is also scrambled, block 2
Descrambled with 4. The signal descrambled in block 24 is subjected to dinterleaving in block 25, which is the reverse of the interleaving in block 8, and
Via the error correction block 26, the digital signal corresponding to the output data of the block 7 of the transmitting device is restored.

The digital signal restored in block 26 is transferred to block 27
The encryption code MC is extracted by the demultiplexer. The extracted encryption code MC is input to the RAM control circuit of block 28, and the RAM adl ff11 circuit outputs the decryption pattern NP corresponding to the encryption code MC from the random access memory RAM of block 29. The decryption pattern NP and the data output from the demultiplexer in block 27 are transferred to block 3.
The original digital signalized audio data DV is decoded by tS-like ORing at 0. If an error in the reproduced data is confirmed by error correction data, interpolation is performed in block 31, and D/A conversion is performed in block 32, and the signal is output as an analog signal. The analog signal outputted from the block 32 is output as audio data to the left audio output circuit and then to the right audio output circuit R via the low-pass filter LPF of the block 33.

In addition, in order to change the decryption pattern stored in the random access memory RAM of the block 29 of the receiving device periodically or irregularly, the microprocessor C of the block 34 can be changed by using an IC card or a communication line.
Via the PLI, data corresponding to the decryption pattern stored in block 5 of the transmitting device is loaded into the random access memory RAM of block 29.

Therefore, even if the same encryption code is used, changing the encryption pattern periodically makes it difficult to decipher the data. In addition, according to the frame configuration example shown in Figure 3, there are theoretically 216 encryption codes added on the transmitting side, so it is possible to improve confidentiality by changing the encryption pattern for each transmission/reception channel or at regular intervals. increases.

In order to cope with changes in the No. 118 pattern for each transmission/reception channel or for a certain period of time, the sending side sends FII code confirmation zero request data to the il+ 111 code @CC for a certain period of time every time the encryption pattern is changed. When the receiving side completes selection of a certain channel, it first reads the encrypted code as described above, determines the decryption pattern, and performs subsequent decryption using the encrypted code. After decoding the decryption code, if you find the W1 authorization request data of the decryption code in the control code shown in Figure 3, read the re-implemented code M reading code again and change the previous decryption pattern. Let's do it.

(Effects of the Invention) As described above, according to the present invention, original information is encrypted and further converted into a digital signal and transmitted from the transmitting device to the receiving device by wireless communication means, and error correction is performed in the receiving device. (1) Deterioration of information due to encryption can be ignored because the decryption pattern is stored in the transmitter and receiver in a state that can be easily and arbitrarily changed.

■ It is easy to change the decryption pattern, making it difficult for third parties to decrypt it.

(2) Since the circuit can be constructed from commonly used microprocessors, memories, LSIs, etc., there is an advantage that the information transmission system can be formed at low cost.

[Brief explanation of the drawing]

The drawings relate to embodiments, and FIG. 1 is an electrical circuit block diagram of a transmitting device in an information transmission system that transmits audio data, FIG. 2 is an electrical circuit block diagram of a receiving device in the information transmission system, and FIG. FIG. 2 is a frame diagram showing an example of a frame configuration every millisecond when transmitting data. 1...Low pass filter block 2...Audio data sampling and quantization block 3...Encoding block 4...Encryption block 5...Random access memory block 6...RA
M III m block 7... Multi-sing block 8... Interleave block 9... Scramble block 10... Pseudo signal generation block 11... 4-phase DPSK modulation block 12... Subcarrier generation block 13 ... Synthesis block 14 ... FM modulation power amplification block 15 ... Transmission antenna 20 ... Reception antenna 21 ... Tuning selection block 22 ... FM demodulation block 23 ... 4-phase DPSK demodulation block 24... Descramble plotter 25... Dinterleave block 26... Error correction block 27... Demultiplex block 28... RA
M control block 29...Random access memory block 30...
Data decoding block 31...Error interpolation block 32...D/A conversion block 33...Low pass filter block 34...Dark decoding pattern data reading block Applicant Comnets Co., Ltd. Agent Patent attorney Hidehiko Okada (external) 3 people) Drawing Part 2 11 No drawings Fig. 3

Claims (1)

[Claims] In a transmission device that transmits information to a specific person by wireless communication means, an exclusive OR of the information and a decryption pattern arbitrarily selected from a storage unit storing a plurality of arbitrarily changeable decryption patterns is provided. After generating a digital signal, a cryptographic code signal corresponding to the selected decryption pattern is multiplexed onto the digital signal, and the multiplexed encrypted digital signal is modulated and power amplified, and then transmitted from a transmitting antenna. The transmitter transmits the signal to a receiving device on the specific person's side, demodulates the received encrypted digital signal in the receiving device, recognizes the code in the demodulated encrypted digital signal, and stores it in the transmitting device. The decryption pattern corresponding to the cipher code transmitted in advance to the receiving device by any means is read out from the storage unit of the receiving device in which the decryption pattern corresponding to the plurality of decryption patterns corresponding to the received decryption pattern is stored, and the read decryption pattern is read out. and the information part in the demodulated encrypted digital signal, and restore the original information by correcting errors in the information part. .