JP7466339B2 - Wireless communication device and wireless communication system - Google Patents

Description

This disclosure relates to a wireless communication device and a wireless communication system.

There is a possibility that voice data transmitted by a wireless communication system may be intercepted by a third party. For this reason, in wireless communication systems, in order to keep the contents of the transmitted voice data secret, the transmitted voice data is encrypted using an encryption key, and the transmitted encrypted voice data is decrypted using the encryption key. The encryption key may be transmitted over the same line as the line that transmits the voice data. The technology described in Patent Document 1 is an example of this.

Japanese Patent Application Laid-Open No. 11-234260

If the encryption key for encrypting the voice data to be transmitted and decrypting the encrypted voice data is transmitted over the same line as the voice data, this has the same effect as reducing the strength of the encryption. This problem also occurs when data other than voice data is transmitted.

This disclosure has been made in light of this problem. The purpose of this disclosure is to improve the confidentiality of transmitted data.

The present disclosure relates to a wireless communication device and a wireless communication system including the wireless communication device.

In a first aspect of the present disclosure, a wireless communication device includes a first communication unit, a second communication unit, a communication key decryption unit, and an encryption unit.

The first communication unit receives the encryption key transmitted via the first line.

The second communication unit receives the encrypted communication key transmitted via the second line.
The first line includes a private network line.
The second line includes a carrier network line.
Private network lines have higher confidentiality than carrier network lines , and carrier network lines can transmit data faster than private network lines .

The call key decryption unit decrypts the encrypted call key using the encryption key.

The encryption section encrypts the transmission data using the communication key decrypted by the communication key decryption section .

The encryption key is transmitted only over the first line, and the encrypted communication key is transmitted only over the second line.

In a second aspect of the present disclosure, a wireless communication device includes a first communication unit, a second communication unit, a communication key decryption unit, and a cryptography unit.

The first communication unit receives the encryption key transmitted via the first line.

The second communication unit receives the encrypted communication key transmitted via the second line.
The first line includes a private network line.
The second line includes a carrier network line.
Private network lines have higher confidentiality than carrier network lines , and carrier network lines can transmit data faster than private network lines .

The call key decryption unit decrypts the encrypted call key using the encryption key.

The encryption/decryption section decrypts the encrypted received data using the communication key decrypted by the communication key decryption section .
The encryption key is transmitted only over the first line, and the encrypted communication key is transmitted only over the second line.

In a third aspect of the present disclosure, a wireless communication device includes a first communication unit, a second communication unit, a communication key calculation unit, and an encryption unit.

The first communication unit receives the encryption key transmitted via the first line.

The second communication unit receives the call key transmitted via the second line.
The first line includes a private network line.
The second line includes a carrier network line.
Private network lines have higher confidentiality than carrier network lines , and carrier network lines can transmit data faster than private network lines .

The communication key calculation unit calculates a new communication key from the encryption key and the communication key.

The encryption unit encrypts the transmission data using the new communication key.

The encryption key is transmitted only over the first line, and the communication key used to calculate the new communication key is transmitted only over the second line.

In a fourth aspect of the present disclosure, a wireless communication device includes a first communication unit, a second communication unit, a communication key calculation unit, and an encryption/decryption unit.

The first communication unit receives the encryption key transmitted via the first line.

The second communication unit receives the call key transmitted via the second line.
The first line includes a private network line.
The second line includes a carrier network line.
Private network lines have higher confidentiality than carrier network lines , and carrier network lines can transmit data faster than private network lines .

The communication key calculation unit calculates a new communication key from the encryption key and the communication key.

The encryption/decryption unit decrypts the encrypted received data using the new communication key.
The encryption key is transmitted only over the first line, and the communication key used to calculate the new communication key is transmitted only over the second line.

According to the present disclosure, an encryption key transmitted over a private network line with high confidentiality is used to encrypt data to be transmitted or to decrypt encrypted data that has been transmitted. This improves the confidentiality of the data to be transmitted.

The objects, features, aspects and advantages of the present disclosure will become more apparent from the following detailed description and the accompanying drawings.

A block diagram illustrating a wireless communication system according to an embodiment 1-2. 2 is a block diagram illustrating an encryption key management unit provided in the wireless communication system of the first embodiment. FIG. 1 is a block diagram illustrating each wireless terminal included in a wireless communication system according to a first embodiment of the present invention; 2 is a block diagram illustrating a call key encryption unit provided in the wireless communication system of the first embodiment. FIG. 2 is a block diagram illustrating a call key decryption unit provided in the wireless communication system of the first embodiment. FIG. 11 is a block diagram illustrating an encryption key management unit provided in a wireless communication system according to a second embodiment of the present invention. FIG. FIG. 11 is a block diagram illustrating each wireless terminal provided in a wireless communication system according to a second embodiment. FIG. 11 is a block diagram illustrating a communication key calculation unit provided in a wireless communication system according to a second embodiment. 13 is a diagram for explaining the generation of a new communication key in the wireless communication system of the second embodiment; FIG.

1. First embodiment
1.1 Wireless Communication System FIG. 1 is a block diagram that illustrates a wireless communication system according to the first embodiment.

The wireless communication system 1 shown in FIG. 1 is a digital wireless communication system for performing voice communication.

As shown in FIG. 1, the wireless communication system 1 includes an encryption key management unit 101, a call distribution unit 102, a private network base station 103, a carrier network base station 104, a first wireless terminal 105a, and a second wireless terminal 105b.

The encryption key management unit 101 and the private network base station 103 are connected to each other so that they can communicate with each other via a private network line 111. The encryption key management unit 101 and the carrier network base station 104 are connected to each other so that they can communicate with each other via a carrier network line 112. The call distribution unit 102 and the carrier network base station 104 are connected to each other so that they can communicate with each other via a carrier network line 112.

The private network base station 103 and each of the wireless terminals 105, the first wireless terminal 105a and the second wireless terminal 105b, are connected to each other so that they can communicate with each other via a first wireless line 121. The operator network base station 104 and each of the wireless terminals 105 are connected to each other so that they can communicate with each other via a second wireless line 122.

As a result, the encryption key management unit 101 and each wireless terminal 105 are communicatively connected to each other via the private network line 111, the private network base station 103, and the first wireless line 121. The encryption key management unit 101 and each wireless terminal 105 are further communicatively connected to each other via the carrier network line 112, the carrier network base station 104, and the second wireless line 122. The call distribution unit 102 and each wireless terminal 105 are communicatively connected to each other via the carrier network line 112, the carrier network base station 104, and the second wireless line 122.

The private network line 111 and the first wireless line 121 have high confidentiality, but can only transmit data at a low speed. The operator network line 112 and the second wireless line 122 have low confidentiality, but can transmit data at a high speed. The operator network line 112 includes the Internet network 131.

The encryption key management unit 101 generates an encryption key and an encrypted call key. The encryption key management unit 101 also manages the encryption key and the encrypted call key. The encryption key management unit 101 also transmits the encryption key to each wireless terminal 105 via the private network line 111, the private network base station 103, and the first wireless line 121. The encryption key management unit 101 also transmits the encrypted call key to each wireless terminal 105 via the carrier network line 112, the carrier network base station 104, and the second wireless line 122. The encryption key management unit 101 is configured by causing a computer to execute a program. All or part of the encryption key management unit 101 may be configured by hardware.

The call distribution unit 102 receives encrypted voice data and control data from each wireless terminal 105 via the second wireless line 122, the carrier network base station 104, and the carrier network line 112. The call distribution unit 102 also transmits encrypted voice data and control data to each wireless terminal 105 via the carrier network line 112, the carrier network base station 104, and the second wireless line 122. The call distribution unit 102 is configured by causing a computer to execute a program. All or part of the call distribution unit 102 may be configured from hardware.

Each wireless terminal 105 is a wireless terminal for performing voice communication. Each wireless terminal 105 receives an encryption key from the encryption key management unit 101 via the private network line 111, the private network base station 103, and the first wireless line 121. Each wireless terminal 105 also receives an encrypted call key from the encryption key management unit 101 via the carrier network line 112, the carrier network base station 104, and the second wireless line 122. Each wireless terminal 105 also uses the encryption key to decrypt the encrypted call key and generate a decrypted call key. Each wireless terminal 105 also transmits encrypted voice data and control data to the call distribution unit 102 via the second wireless line 122, the carrier network base station 104, and the carrier network line 112. Each wireless terminal 105 also receives encrypted voice data and control data from the call distribution unit 102 via the carrier network line 112, the carrier network base station 104, and the second wireless line 122.

When voice communication is performed between the first wireless terminal 105a and the second wireless terminal 105b, the first wireless terminal 105a converts voice into voice data. The first wireless terminal 105a also encrypts the voice data using the decrypted call key to generate encrypted voice data. The first wireless terminal 105a also transmits the encrypted voice data. The encrypted voice data is transmitted by the second wireless line 122, the carrier network base station 104, and the carrier network line 112. The call distribution unit 102 receives the transmitted encrypted voice data. The call distribution unit 102 also transmits the encrypted voice data. The encrypted voice data is transmitted by the carrier network line 112, the carrier network base station 104, and the second wireless line 122. The second wireless terminal 105b receives the transmitted encrypted voice data. The second wireless terminal 105b also decrypts the encrypted voice data using the decrypted call key to generate decrypted voice data.

1.2 Encryption Key Management Unit FIG. 2 is a block diagram showing a schematic diagram of an encryption key management unit provided in the wireless communication system according to the first embodiment.

As shown in FIG. 2, the encryption key management unit 101 includes an encryption key generation unit 201, a call key generation unit 202, a call key encryption unit 203, an encryption key distribution unit 204, and a call key distribution unit 205.

The encryption key generation unit 201 generates an encryption key K1. The encryption key K1 is a random number, and is a short encryption key having a key length of, for example, 128 bits. The encryption key generation unit 201 also outputs the encryption key K1 to the call key encryption unit 203 and the encryption key distribution unit 204.

The call key generation unit 202 generates a call key K2. The call key K2 is a random number, and is a long call key having a key length of, for example, 12,800 bits. The call key generation unit 202 also outputs the call key K2 to the call key encryption unit 203.

The call key encryption unit 203 encrypts the call key K2 using the encryption key K1 to generate an encrypted call key K3. The call key encryption unit 203 also outputs the encrypted call key K3 to the call key delivery unit 205.

The encryption key delivery unit 204 transmits the encryption key K1 to the private network base station 103 via the private network line 111.

The call key delivery unit 205 transmits the encrypted call key K3 to the carrier network base station 104 via the carrier network line 112.

1.3 Wireless Terminal FIG. 3 is a block diagram showing a schematic diagram of each wireless terminal included in the wireless communication system according to the first embodiment.

Each wireless terminal 105 shown in FIG. 3 is a wireless communication device.

As shown in FIG. 3, each wireless terminal 105 includes a private network communication unit 301, a carrier network communication unit 302, a call key decryption unit 303, a microphone 304, an analog/digital (A/D) conversion unit 305, an audio compression unit 306, an audio encryption unit 307, an audio encryption/decryption unit 308, an audio decoding unit 309, a digital/analog (D/A) conversion unit 310, and a speaker 311.

The speech key decryption unit 303, the audio compression unit 306, the audio encryption unit 307, the audio encryption/decryption unit 308, and the audio decryption unit 309 are configured by having a computer execute a program. All or part of the speech key decryption unit 303, the audio compression unit 306, the audio encryption unit 307, the audio encryption/decryption unit 308, and the audio decryption unit 309 may be configured by hardware.

First, we will explain the configuration by which each wireless terminal 105 generates the decrypted call key K4.

The private network communication unit 301 receives a radio signal from the private network base station 103 via the first radio line 121. The private network communication unit 301 also converts the radio signal into a radio signal. The private network communication unit 301 also demodulates the radio converted radio signal. As a result, the private network communication unit 301 receives the encryption key K1 transmitted via the private network line 111. The private network communication unit 301 outputs the encryption key K1 to the call key decryption unit 303.

The carrier network communication unit 302 receives a radio signal from the carrier network base station 104 via the second radio line 122. The carrier network communication unit 302 also performs radio conversion of the radio signal. The carrier network communication unit 302 also demodulates the radio converted radio signal. As a result, the carrier network communication unit 302 receives the encrypted call key K3 transmitted via the carrier network line 112. The carrier network communication unit 302 outputs the encrypted call key K3 to the call key decryption unit 303.

The call key decryption unit 303 uses the encryption key K1 to decrypt the encrypted call key K3 and generate a decrypted call key K4. The call key decryption unit 303 also outputs the decrypted call key K4 to the audio encryption unit 307 and the audio encryption/decryption unit 308.

Next, we will explain the configuration for each wireless terminal 105 to transmit audio data.

The microphone 304 converts the voice uttered by the speaker into an audio signal. The microphone 304 outputs the audio signal to the A/D conversion unit 305.

The A/D conversion unit 305 converts the audio signal, which is an analog signal, into audio data, which is a digital signal. The A/D conversion unit 305 outputs the audio data to the audio compression unit 306.

The audio compression unit 306 compresses the audio data to generate transmission data. In doing so, the audio compression unit 306 compresses the audio data by audio encoding, for example, every 20 milliseconds. The audio compression unit 306 also outputs the transmission data to the audio encryption unit 307. The transmission data is audio data.

The voice encryption unit 307 encrypts the transmission data using the decrypted call key K4 to generate encrypted transmission data. The voice encryption unit 307 outputs the encrypted transmission data to the carrier network communication unit 302. The encrypted transmission data is voice data.

The carrier network communication unit 302 modulates a carrier wave with the encrypted transmission data to generate a radio signal. The carrier network communication unit 302 also performs radio conversion of the radio signal. The carrier network communication unit 302 also transmits the radio converted radio signal to the carrier network base station 104 via the second radio line 122. As a result, the carrier network communication unit 302 transmits the encrypted transmission data via the carrier network line 112.

Next, we will explain the configuration for each wireless terminal 105 to receive audio data.

The carrier network communication unit 302 receives a radio signal from the carrier network base station 104 via the second radio line 122. The carrier network communication unit 302 also performs radio conversion of the radio signal. The carrier network communication unit 302 also demodulates the radio converted radio signal. In this way, the carrier network communication unit 302 receives encrypted received data transmitted via the carrier network line 112. The carrier network communication unit 302 outputs the encrypted received data to the audio encryption/decryption unit 308. The encrypted received data is audio data.

The audio encryption/decryption unit 308 uses the decrypted communication key K4 to decrypt the encrypted received data described above to generate decrypted received data. The audio encryption/decryption unit 308 also outputs the decrypted received data to the audio decoding unit 309. The decrypted received data is audio data.

The audio decoding unit 309 audio-decodes the decoded received data to obtain audio data. In this case, the audio decoding unit 309 audio-decodes the decoded received data, for example, every 20 milliseconds. The audio decoding unit 309 also outputs the audio data to the D/A conversion unit 310.

The D/A conversion unit 310 converts the audio data, which is a digital signal, into an audio signal, which is an analog signal. The D/A conversion unit 310 outputs the audio signal to the speaker 311.

Speaker 311 converts the audio signal into sound.

1.4 Call Key Encryption Unit FIG. 4 is a block diagram showing a schematic diagram of the call key encryption unit provided in the wireless communication system according to the first embodiment.

The call key encryption unit 203 includes an encryption unit 401, as shown in FIG. 4.

When the communication key K2 is updated, the encryption unit 401 encrypts the communication key K2 using the encryption key K1 to generate an encrypted communication key K3. The encryption unit 401 also outputs the encrypted communication key K3 to the communication key delivery unit 205. The encryption is performed using a cryptographic algorithm of a common key cryptosystem such as DES (Data Encryption Standard), AES (Advanced Encryption Standard), or Camellia.

1.5 Call Key Decryption Unit, Audio Encryption Unit, and Audio Encryption Decryption Unit FIG. 5 is a block diagram showing a schematic diagram of the call key decryption unit provided in the wireless communication system of the first embodiment.

As shown in FIG. 5, the call key decryption unit 303 includes a decryption unit 501, a call key storage unit 502, and a division unit 503.

When the communication key K2 is updated to update the encrypted communication key K3, the decryption unit 501 uses the encryption key K1 to decrypt the encrypted communication key K3 and generate a decrypted communication key K4. The decryption is performed by an encryption algorithm of a common key encryption method such as DES, AES, or Camellia. The decryption unit 501 stores the decrypted communication key K4 in the communication key storage unit 502.

When a voice call is made, the division unit 503 reads out the decrypted call key K4 stored in the call key storage unit 502. The division unit 503 also divides the decrypted call key K4 into multiple call keys K5. The division unit 503 divides the decrypted call key K4, for example, into 128-bit pieces. The division unit 503 outputs the multiple call keys K5 to the audio encryption unit 307 and the audio encryption/decryption unit 308.

The voice encryption unit 307 encrypts the transmission data using a call key included in the multiple call keys K5. If the decrypted call key K4 is divided into 128 bits, the voice encryption unit 307 encrypts the transmission data using one call key having a key length of 128 bits. The voice encryption unit 307 changes the call key used at a set period. The set period is, for example, 20 milliseconds. If the decrypted call key K4 has a key length of 12,800 bits and is divided into 100, and the set period is 20 milliseconds, the voice encryption unit 307 changes the call key for encrypting the transmission data every 20 milliseconds, and repeats changing the call key for encrypting the transmission data every time a decrypted call key K4 is generated, 100 times.

The audio encryption/decryption unit 308 decrypts the encrypted received data using a call key included in the multiple call keys K5. If the decrypted call key K4 is divided into 128 bits, the audio encryption/decryption unit 308 decrypts the encrypted received data using one call key having a key length of 128 bits. The audio encryption/decryption unit 308 changes the call key to be used at a set period. The set period is, for example, 20 milliseconds. If the decrypted call key K4 has a key length of 12,800 bits and is divided into 100, and the set period is 20 milliseconds, the audio encryption/decryption unit 308 changes the call key for decrypting the encrypted received data every 20 milliseconds, and repeats changing the call key for decrypting the encrypted received data every time a decrypted call key K4 is generated, 100 times.

As a result, in each wireless terminal 105, the encrypted communication key K3 is decrypted using the encryption key K1 transmitted by the private network line 111, which has high confidentiality. In addition, the decrypted communication key K4 is used to encrypt the transmission data and decrypt the encrypted reception data. Therefore, the high confidentiality of the private network line 111 ensures the confidentiality of the transmitted data and the received data. Therefore, according to embodiment 1, the confidentiality of the transmitted data and the received data can be improved.

In addition, in each wireless terminal 105, the long decrypted call key K4 is divided, and the call key for encrypting the transmission data and the call key for decrypting the encrypted received data are changed at a set period. This makes it possible to further improve the confidentiality of the transmitted transmission data and received data. Note that since the long decrypted call key K4 is transmitted over the carrier network line 112, which can transmit data at high speeds, the length of the decrypted call key K4 does not result in a significant increase in transmission time.

1.6 Modifications In the first embodiment, each wireless terminal 105 has a transmission function for transmitting encrypted transmission data and a reception function for receiving encrypted reception data. However, each wireless terminal 105 may have only one of the transmission function and the reception function.

In addition, in the first embodiment, the wireless communication system 1 is a wireless communication system for performing voice communication. Therefore, the data transmitted is voice data. However, the wireless communication system 1 may be a wireless communication system for performing communication other than voice communication. Therefore, the data transmitted may be data other than voice data. When the data transmitted is data other than voice data, the voice encryption unit 307, which is an encryption unit that encrypts voice data, is replaced with an encryption unit that encrypts data other than voice data. In addition, the voice encryption/decryption unit 308, which is an encryption/decryption unit that decrypts encrypted voice data, is replaced with an encryption/decryption unit that decrypts encrypted data other than voice data.

2. Second embodiment
2.1 Wireless Communication System FIG. 1 is also a block diagram that diagrammatically illustrates a wireless communication system according to the second embodiment.

The wireless communication system 2 of the second embodiment shown in FIG. 1 differs from the wireless communication system 1 of the first embodiment mainly in the points described below. For points not described below, the wireless communication system 2 of the second embodiment also adopts the same configuration as that adopted in the wireless communication system 1 of the first embodiment.

2.2 Encryption Key Management Unit FIG. 6 is a block diagram showing an encryption key management unit provided in the wireless communication system according to the second embodiment.

As shown in FIG. 6, the encryption key management unit 101 includes an encryption key generation unit 201, a call key generation unit 202, a fixed key storage unit 601, a call key encryption unit 203, an encryption key distribution unit 204, and a call key distribution unit 205.

The encryption key generation unit 201, the call key generation unit 202, the call key encryption unit 203, the encryption key distribution unit 204, and the call key distribution unit 205 provided in the wireless communication system 2 of the second embodiment correspond to the encryption key generation unit 201, the call key generation unit 202, the call key encryption unit 203, the encryption key distribution unit 204, and the call key distribution unit 205 provided in the wireless communication system 1 of the first embodiment, respectively.

The encryption key generation unit 201 outputs the encryption key K1 to the encryption key distribution unit 204.

The fixed key storage unit 601 stores the fixed key K6. The fixed key K6 is a random number, and is a short fixed key having a key length of, for example, 128 bits. The fixed key K6 is fixed. The fixed key storage unit 601 outputs the fixed key K6 to the call key encryption unit 203.

The call key encryption unit 203 encrypts the call key K2 using the fixed key K6 to generate an encrypted call key K3.

2.3 Wireless Terminal FIG. 7 is a block diagram showing a schematic diagram of each wireless terminal included in the wireless communication system according to the second embodiment.

As shown in FIG. 7, each wireless terminal 105 includes a private network communication unit 301, a carrier network communication unit 302, a call key calculation unit 701, a fixed key storage unit 702, a microphone 304, an A/D conversion unit 305, an audio compression unit 306, an audio encryption unit 307, an audio encryption/decryption unit 308, an audio decoding unit 309, a D/A conversion unit 310, and a speaker 311.

The private network communication unit 301, the carrier network communication unit 302, the microphone 304, the A/D conversion unit 305, the voice compression unit 306, the voice encryption unit 307, the voice encryption/decryption unit 308, the voice decoding unit 309, the D/A conversion unit 310, and the speaker 311 provided in the wireless communication system 2 of the second embodiment correspond to the private network communication unit 301, the carrier network communication unit 302, the microphone 304, the A/D conversion unit 305, the voice compression unit 306, the voice encryption unit 307, the voice encryption/decryption unit 308, the voice decoding unit 309, the D/A conversion unit 310, and the speaker 311 provided in the wireless communication system 1 of the first embodiment, respectively.

The fixed key storage unit 702 stores the fixed key K6, similar to the fixed key storage unit 601. The fixed key K6 is a random number, and is a short fixed key having a key length of, for example, 128 bits. The fixed key K6 is fixed. The fixed key storage unit 702 outputs the fixed key K6 to the call key calculation unit 701.

The carrier network communication unit 302 receives the call key K3.

The call key calculation unit 701 calculates a new call key K7 from the encryption key K1 and the call key K3. The call key K3 is an encrypted call key. The call key calculation unit 701 uses the fixed key K6 described above to decrypt the encrypted call key K3 to generate a decrypted call key. The call key calculation unit 701 also calculates a new call key K7 from the encryption key K1 and the decrypted call key. The call key calculation unit 701 also outputs the new call key K7 to the audio encryption unit 307 and the audio encryption/decryption unit 308.

The voice encryption unit 307 encrypts the transmission data using the new speech key K7 to generate encrypted transmission data.

The audio encryption/decryption unit 308 decrypts the encrypted received data using the new speech key K7 to generate decrypted received data.

2.4 Communication Key Decryption Unit FIG. 8 is a block diagram showing a communication key calculation unit provided in the wireless communication system according to the second embodiment.

As shown in FIG. 8, the call key calculation unit 701 includes a decryption unit 501, a call key storage unit 502, a key derivation unit 801, and a key combination unit 802.

When the call key K2 is updated and the encrypted call key K3 is updated, the decryption unit 501 decrypts the encrypted call key K3 using the fixed key K6 to generate a decrypted call key K8. The decryption unit 501 stores the decrypted call key K8 in the call key storage unit 502.

The key derivation unit 801 derives a derived key K9 from the encryption key K1 using a key derivation function (KDF). The derived key K9 has a key length of, for example, 12,800 bits. The key derivation unit 801 also outputs the derived key K9 to the key combination unit 805.

When a voice call is made, the key combining unit 802 reads out the decrypted call key K8 stored in the call key storage unit 502. The key combining unit 802 also combines the decrypted call key K8 and the derived key K9 to generate a new call key K7. The key combining unit 802 also outputs the new call key K7 to the audio encryption unit 307 and the audio encryption/decryption unit 308.

2.5 Combining Communication Key and Derived Key FIG. 9 is a diagram for explaining the generation of a new communication key in the wireless communication system according to the second embodiment.

When combining the decrypted call key K8 and the derived key K9, the key combining unit 802 divides the decrypted call key K8 into multiple call keys K8a, K8b, K8c, K8d, and K8e, as shown in FIG. 9. At that time, the key combining unit 802 divides the decrypted call key K8 into 128-bit pieces, for example.

When combining the decrypted communication key K8 and derived key K9, the key combining unit 802 divides the derived key K9 into multiple derived keys K9a, K9b, K9c, K9d, and K9e, as shown in FIG. 9. At this time, the key combining unit 802 divides the derived key K9 into, for example, 128-bit pieces.

As shown in FIG. 9, the key combining unit 802 performs an exclusive OR operation between the multiple call keys K8a, K8b, K8c, K8d, and K8e and the multiple derived keys K9a, K9b, K9c, K9d, and K9e to generate multiple call keys K7a, K7b, K7c, K7d, and K7e, respectively. The multiple call keys K7a, K7b, K7c, K7d, and K7e constitute a new call key K7. The key combining unit 802 also outputs the multiple call keys K7a, K7b, K7c, K7d, and K7e to the audio encryption unit 307 and the audio encryption/decryption unit 308. The multiple call keys K7a, K7b, K7c, K7d, and K7e are output sequentially, for example, every 20 milliseconds.

The voice encryption unit 307 encrypts the transmission data using a call key included in the multiple call keys K7a, K7b, K7c, K7d, and K7e. Each of the multiple call keys K7a, K7b, K7c, K7d, and K7e has a key length of, for example, 128 bits. The voice encryption unit 307 changes the call key used at a set period. The set period is, for example, 20 milliseconds. When the set period is 20 milliseconds, the voice encryption unit 307 changes the call key used to encrypt the transmission data every 20 milliseconds.

The audio encryption/decryption unit 308 decrypts the encrypted received data using a communication key included in the multiple communication keys K7a, K7b, K7c, K7d, and K7e. Each of the multiple communication keys K7a, K7b, K7c, K7d, and K7e has a key length of, for example, 128 bits. The audio encryption/decryption unit 308 changes the communication key used at a set period. The set period is, for example, 20 milliseconds. When the set period is 20 milliseconds, the audio encryption/decryption unit 308 changes the communication key for decrypting the encrypted received data every 20 milliseconds.

As a result, in each wireless terminal 105, a new communication key K7 is generated from the encryption key K1 transmitted by the private network line 111, which has high confidentiality. In addition, the new communication key K7 is used to encrypt the transmitted data and decrypt the encrypted received data. Therefore, the high confidentiality of the private network line 111 ensures the confidentiality of the transmitted data and received data. Therefore, according to embodiment 2, the confidentiality of the transmitted data and received data can be improved.

In addition, in each wireless terminal 105, multiple communication keys K7a, K7b, K7c, K7d, and K7e are generated, and the communication keys for encrypting transmission data and for decrypting encrypted received data are changed at set intervals. This further improves the confidentiality of the transmitted data and received data.

The embodiments can be freely combined, modified, or omitted as appropriate.

Although the present disclosure has been described in detail, the above description is illustrative in all respects and is not limiting. It is understood that countless variations not illustrated can be envisioned.

1, 2 Wireless communication system, 101 Encryption key management unit, 102 Speech distribution unit, 105 Wireless terminal, 111 Private network line, 112 Carrier network line, 201 Encryption key generation unit, 202 Speech key generation unit, 203 Speech key encryption unit, 204 Encryption key distribution unit, 205 Speech key distribution unit, 301 Private network communication unit, 302 Carrier network communication unit, 303 Speech key decryption unit, 306 Voice compression unit, 307 Voice encryption unit, 308 Voice encryption/decryption unit, 309 Voice decryption unit, 701 Speech key calculation unit, 702 Fixed key storage unit.

Claims (22)

a first communication unit that receives an encryption key transmitted via a first line;
a second communication unit that receives the encrypted call key transmitted via the second line,
the first line includes a private network line;
the second line includes a carrier network line;
The private network line has higher confidentiality than the carrier network line , and the carrier network line can transmit data at a higher speed than the private network line ,
a call key decryption unit that decrypts the encrypted call key using the encryption key;
an encryption unit that encrypts transmission data using the communication key decrypted by the communication key decryption unit;
Further equipped with
A wireless communication device, wherein the encryption key is transmitted only via the first line, and the encrypted communication key is transmitted only via the second line. 2. The wireless communication device according to claim 1, wherein the transmission data encrypted by said encryption unit is transmitted via said second line. The call key decryption unit divides the decrypted call key into a plurality of call keys,
3. The wireless communication device according to claim 1, wherein the encryption unit encrypts the transmission data using a communication key included in the plurality of communication keys, and changes the communication key to be used at a set cycle. 4. The wireless communication device according to claim 1, wherein the transmission data and the transmission data encrypted by the encryption unit are voice data. a first communication unit that receives an encryption key transmitted via a first line;
a second communication unit that receives the encrypted call key transmitted via the second line,
the first line includes a private network line;
the second line includes a carrier network line;
The private network line has higher confidentiality than the carrier network line , and the carrier network line can transmit data at a higher speed than the private network line ,
a call key decryption unit that decrypts the encrypted call key using the encryption key;
a decryption unit that decrypts the encrypted received data using the communication key decrypted by the communication key decryption unit;
Further equipped with
A wireless communication device, wherein the encryption key is transmitted only via the first line, and the encrypted communication key is transmitted only via the second line. 6. The wireless communication device according to claim 5, wherein the encrypted reception data is received via the second line. The call key decryption unit divides the decrypted call key into a plurality of call keys,
7. The wireless communication device according to claim 5, wherein the encryption/decryption unit decrypts the encrypted received data using a communication key included in the plurality of communication keys, and changes the communication key to be used at a set cycle. 8. The wireless communication device according to claim 5, wherein the encrypted received data and the received data decoded by the encryption/decryption section are voice data. an encryption unit that encrypts transmission data using the communication key decrypted by the communication key decryption unit,
9. The wireless communication device according to claim 5, wherein the transmission data encrypted by said encryption unit is transmitted via said second line. a first communication unit that receives an encryption key transmitted via a first line;
a second communication unit that receives the call key transmitted via the second line,
the first line includes a private network line;
the second line includes a carrier network line;
The private network line has higher confidentiality than the carrier network line , and the carrier network line can transmit data at a higher speed than the private network line ,
a communication key calculation unit for calculating a new communication key from the encryption key and the communication key;
an encryption unit that encrypts transmission data using the new communication key;
Further equipped with
A wireless communication device, wherein the encryption key is transmitted only via the first line, and the communication key used to calculate the new communication key is transmitted only via the second line. 11. The wireless communication device according to claim 10, wherein the transmission data encrypted by said encryption unit is transmitted via said second line. the new call key is composed of a plurality of call keys;
12. The wireless communication device according to claim 10, wherein the encryption unit encrypts the transmission data using a communication key included in the plurality of communication keys, and changes the communication key to be used at a set cycle. 13. The wireless communication device according to claim 10, wherein the transmission data and the transmission data encrypted by the encryption unit are voice data. a first communication unit that receives an encryption key transmitted via a first line;
a second communication unit that receives the call key transmitted via the second line,
the first line includes a private network line;
the second line includes a carrier network line;
The private network line has higher confidentiality than the carrier network line , and the carrier network line can transmit data at a higher speed than the private network line ,
a communication key calculation unit for calculating a new communication key from the encryption key and the communication key;
a decryption unit that decrypts the encrypted received data by using the new communication key;
Further equipped with
A wireless communication device, wherein the encryption key is transmitted only via the first line, and the communication key used to calculate the new communication key is transmitted only via the second line. 15. The wireless communication device according to claim 14, wherein the encrypted received data is transmitted via the second line. the new call key is composed of a plurality of call keys;
16. The wireless communication device according to claim 14, wherein the encryption/decryption unit decrypts the encrypted received data using a communication key included in the plurality of communication keys, and changes the communication key to be used at a set cycle. 17. The wireless communication device according to claim 14, wherein the encrypted received data and the received data decoded by the encryption/decryption unit are voice data. an encryption unit that encrypts transmission data using the new communication key;
18. The wireless communication device according to claim 14, wherein the transmission data encrypted by said encryption unit is transmitted via said second line. A fixed key storage unit is provided for storing a fixed key,
the call key is an encrypted call key;
19. The wireless communication device according to claim 10, wherein the communication key calculation unit decrypts the encrypted communication key using the fixed key to generate a decrypted communication key, and calculates the new communication key from the encryption key and the decrypted communication key. 20. The wireless communication device of claim 19, wherein the communication key calculation unit derives a derived key from the encryption key using a key derivation function, and generates the new communication key by combining the decrypted communication key and the derived key. A wireless communication device according to any one of claims 1 to 9;
an encryption key management unit that transmits the encryption key to the wireless communication device only via the first line and transmits the encrypted communication key to the wireless communication device only via the second line;
A wireless communication system comprising: A wireless communication device according to any one of claims 10 to 20;
an encryption key management unit that transmits the encryption key to the wireless communication device only via the first line and transmits the communication key to the wireless communication device only via the second line;
A wireless communication system comprising:

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