HK1103939B - Communication system and communication device - Google Patents

Description

Communication system and communication device

Technical Field

The present invention relates to a communication system and a secure communication device capable of transmitting and receiving data by wireless communication.

Background

Conventionally, with the advancement of information technology, a communication system has been established in which an information processing apparatus such as a computer utilizes a communication medium such as a WLAN (wireless local area network) or the likeWireless communication devices such as (bluetooth) are connected to each other in order to transmit and receive information including files and data and share the information.

In recent years, apparatuses in which a long-distance communication function is installed in which a communication device capable of long-distance communication using Bluetooth or the like is installed on a mobile phone or a personal computer are used to transmit and receive large-capacity data including moving picture data and music data (see, for example, unexamined japanese patent application publication No. 2003-324446).

In order to reduce the risk in terms of security in long-distance data communication, it has become common to introduce data encryption processing even in long-distance communication. Security risks include third parties listening to and changing data with devices equipped with long-range communication capabilities.

It is necessary to identify a communication party in order to perform an encryption process in long-distance communication using bluetooth or the like. However, since the long-distance communication has a wide communication area, an unexpected device in which the long-distance communication function is installed may be identified as a communication party.

Even if the communicating parties are identified, the session key used to initiate the more secure communication must be shared between the communicating parties. However, since the long-distance communication has a wide communication area, there is a possibility that the session key is listened to and decrypted by a third party having the device in which the long-distance communication function is installed when the session key is transmitted to the communication party. Therefore, it is necessary to increase the strength of the session key, for example, by lengthening the session key, and thus to make a device in which a long-distance communication function is installed have higher processing capability.

It is therefore an object of the present invention to provide a new and improved communication system and communication device which are capable of easily identifying a communicating party and securely sharing a session key between communication devices even when the communication devices have a not too high processing capability.

Disclosure of Invention

In order to solve the above problem, according to a first aspect of the present invention, a communication system includes a plurality of communication devices. The first communication device includes: a short-range active communication means for transmitting an inquiry signal to a short-range external communication device by electromagnetic waves and waiting for a response to the inquiry signal; a long-distance communication device capable of communicating by electromagnetic waves in a wider range than a communication area of the short-distance active communication device; switching means for switching to either the short-range active communication means or the long-range communication means; and asymmetric key generation means for generating a pair of keys including an encryption key and a decryption key corresponding to the encryption key, the encryption key and the decryption key in the pair of keys being asymmetric with each other. The second communication device includes: short-range passive communication means for receiving an inquiry signal from a short-range external communication device and transmitting a response signal in response to the inquiry signal; a long-distance communication device capable of communicating by electromagnetic waves in a wider range than a communication area of the short-range passive communication device; switching means for switching to either the short-range passive communication means or the long-range communication means; session key generation means for generating a random number and generating a session key using the generated random number; and encrypting means for encrypting the session key. The second communication device encrypts the session key into an encrypted session key using the encryption key transmitted from the first communication device, and transmits the encrypted session key to the first communication device. The first communication apparatus decrypts the encrypted session key into the session key using the decryption key, and transmits a communication switching request signal for requesting switching to the long-distance communication device and communication using the long-distance communication device to the second communication apparatus.

The short-range active communication means may transmit the identification information assigned to the short-range active communication means to the short-range passive communication means together with the encryption key, and the short-range passive communication means may provide the identification information assigned to the short-range passive communication means together with the encrypted session key to the short-range active communication means so as to provide the identification information of the communication party to the long-range communication means provided in the first and second communication devices.

In order to solve the above problem, according to another aspect of the present invention, a communication apparatus includes: a short-range active communication means for transmitting an inquiry signal to a short-range external communication device by electromagnetic waves and waiting for a response to the inquiry signal; a long-distance communication device capable of communicating by electromagnetic waves in a wider range than a communication area of the short-distance active communication device; switching means for switching to either the short-range active communication means or the long-range communication means; and asymmetric key generation means for generating a pair of keys including an encryption key and a decryption key corresponding to the encryption key, the encryption key and the decryption key in the pair of keys being asymmetric with each other. The communication apparatus decrypts the encrypted session key transmitted from the external communication apparatus using the decryption key, and transmits a communication switching request signal for requesting switching to the long-distance communication device and performing communication using the long-distance communication device to the external communication apparatus.

The short range active communication means may transmit identification information assigned to the short range active communication means to the external communication device together with the encryption key.

The short-range active communication means may transmit identification information assigned to the short-range active communication means to the external communication device together with the encryption key, and may receive the identification information assigned to the external communication device together with the encrypted session key from the external communication device so as to provide identification information of the communication party to the long-range communication means and the external communication device provided in the communication device.

In order to solve the above problem, according to another embodiment of the present invention, a second communication device among communication devices includes: short-range passive communication means for receiving an inquiry signal from a short-range external communication device and transmitting a response signal in response to the inquiry signal; a long-distance communication device capable of communicating by electromagnetic waves in a wider range than a communication area of the short-range passive communication device; switching means for switching to either the short-range passive communication means or the long-range communication means; session key generation means for generating a random number and generating a session key using the generated random number; and encrypting means for encrypting the session key. The communication apparatus encrypts the session key into an encrypted session key using an encryption key transmitted from the external communication apparatus and transmits the encrypted session key to the first communication apparatus, and receives a communication switching request signal, which requests switching to the long-distance communication device and communication using the long-distance communication device, from the external communication apparatus.

The short-range passive communication means may receive identification information assigned to the external communication device together with the encryption key.

The short-range passive communication means may receive the identification information assigned to the external communication device together with the encryption key, and may provide the identification information assigned to the short-range passive communication means together with the encrypted session key to the external communication device so as to provide the identification information of the communication party to the long-range communication means and the external communication device provided in the communication device.

As described above, according to the present invention, since it is possible to easily identify a communication party in short-range communication and share a session key between a communication device and the communication party even if the communication device has not so high processing capability, it is possible to reduce the risk of the session key being intercepted and decrypted and to realize long-range data communication.

Drawings

Fig. 1 is a schematic diagram showing the structure of a communication system according to one embodiment.

Fig. 2 is a block diagram schematically illustrating the structure of a secure communication device according to one embodiment.

Fig. 3 is a block diagram schematically showing the structure of another secure communication apparatus according to an embodiment.

Fig. 4 is a block diagram schematically illustrating the structure of an active communication unit according to one embodiment.

Fig. 5 is a sequence diagram schematically showing a series of communication processes in the communication system according to one embodiment.

Fig. 6 is a diagram illustrating short-range communication between devices having a secure communication function installed, according to an embodiment.

Fig. 7 is a diagram illustrating a process of establishing secure communication in short-range communication between devices in which a secure communication function is installed according to an embodiment.

Fig. 8 is another diagram illustrating a process of establishing secure communication in short-range communication between devices in which a secure communication function is installed according to an embodiment.

Detailed Description

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numbers are used in the following description and the drawings to identify components having substantially the same function and structure. A repetitive description of such components is omitted here.

A communication system according to one embodiment will now be described with reference to fig. 1. Fig. 1 is a schematic diagram showing the structure of a communication system according to this embodiment.

As shown in fig. 1, the communication system according to this embodiment includes at least a plurality of devices 10(10a, 10b, …, 10j) mounted with a secure communication function.

Further, as shown in fig. 1, each of a mobile phone, a PDA (personal digital assistant), a pen, a personal computer, and the like includes a short range communication means according to Near Field Communication (NFC) or the like, uses bluetoothEtc., and other wireless communication devices for securely performing any type of data communication.

The secure communication means exchanging information between different devices 10 mounted with a secure communication function in a state in which the information is prevented from being intercepted or changed by a third party using the device 10 mounted with a secure communication function and the information is protected without impairing the security or integrity of the information.

In the communication system shown in fig. 1, one or more of the devices 10a to 10f mounted with the secure communication function must be a reader/writer in order to establish short-range communication using the NFC technology.

The NFC technology in short-range communication uses electromagnetic waves transmitted from a reader/writer to establish device communication between an IC card and the reader/writer.

Further, the NFC technology is physically superior to wireless communication using, for example, bluetooth or through a wireless LAN in terms of security because the communication range of the NFC technology corresponding to the distance between devices is as short as about 10 cm. For example, when using NFC technology, it is difficult for a third party to listen to information with the device 10 in which the secure communication function is installed. Further, the NFC technology has a feature different from that of the known communication technology, in which automatic update is performed when a device capable of near field communication, in which a secure communication function is installed, is located within a predetermined range.

Although the communication system according to this embodiment has a wireless communication function according to NFC or using Bluetooth, for example, the present invention is not limited to this example. The present invention is applicable to the case where any other wireless communication protocol is used.

As described above, NFC is a communication protocol for performing short-range communication by electromagnetic induction. In NFC, a carrier having a single frequency is used between devices 10 in which a secure communication function is installed. For example, the frequency of the carrier wave is equal to 13.56 mhz within the ISM (industrial scientific Medical) frequency band.

Short-range communication means communication in which communication devices within a distance of about 10cm communicate with each other, and includes communication established by devices (or housings of devices) contacting each other. Long-range communication means communication in which communication devices within a distance longer than that in short-range communication (about 10cm) communicate with each other. For example, in bluetooth, communication devices within a distance shorter than 10m can communicate with each other.

There are two communication modes in NFC, namely a passive mode and an active mode. To describe these two communication modes, communication between the device 10a with the secure communication function installed and the device 10b with the secure communication function installed, among the devices 10a to 10f with the secure communication function installed shown in fig. 1, is exemplified.

In the passive mode, the electromagnetic wave (carrier wave corresponding to the electromagnetic wave) generated by itself is modulated in the device 10a with the secure communication function installed or the device 10b with the secure communication function installed (for example, the device 10a with the secure communication function installed).

After the modulation, the device with the secure communication function mounted 10a transmits the modulated data to another device with the secure communication function mounted, that is, the device with the secure communication function mounted 10 b. The device with the secure communication function 10b performs load modulation on the electromagnetic wave (carrier wave corresponding to the electromagnetic wave) generated by the device with the secure communication function 10a, and returns the modulated data to the device with the secure communication function 10 a.

In contrast, in the active mode, both the device 10a mounted with the secure communication function and the device 10b mounted with the secure communication function modulate an electromagnetic wave (a carrier wave corresponding to the electromagnetic wave) generated by themselves and transmit the modulated data.

In short-range communication by electromagnetic induction, for example, near field communication, a device that first outputs an electromagnetic wave to start communication and actively initiates communication is called an initiator. The initiator sends a command (request) to the correspondent, and the correspondent returns a response in response to the command to establish a short-range communication. The device that returns a response in response to a command from the initiator and is the communicating party is called the target.

For example, when the device 10e with the secure communication function installed in fig. 1 outputs an electromagnetic wave to start communication with the device 10a with the secure communication function installed, the device 10e with the secure communication function installed is an initiator, and the device 10a with the secure communication function installed is a target.

In the passive mode, for example, when the device 10j with the secure communication function mounted in fig. 1 is an initiator and the device 10g with the secure communication function mounted in fig. 1 is a target, the device 10j with the secure communication function mounted as the initiator continuously outputs an electromagnetic wave, modulates the electromagnetic wave output by itself, and transmits data to the device 10g with the secure communication function mounted as the target. The device 10g with the secure communication function mounted performs load modulation on the electromagnetic wave output from the device 10j with the secure communication function mounted as an initiator, and transmits the modulated data to the device 10j with the secure communication function mounted.

In contrast, in the data transmission in the active mode, the device 10j having the secure communication function installed as the initiator starts outputting an electromagnetic wave, modulates the electromagnetic wave, and transmits the modulated data to the device 10g having the secure communication function installed as the target. After the end of the data transmission, the device 10j mounted with the secure communication function stops the output of the electromagnetic wave. Similarly, in this data transmission, the device 10g as the target to which the secure communication function is installed also starts outputting an electromagnetic wave, modulates the electromagnetic wave, and transmits the modulated data to the device 10j as the target to which the secure communication function is installed. After the end of the data transmission, the device 10g mounted with the secure communication function stops the output of the electromagnetic wave.

According to this embodiment, as described above, short-range communication according to NFC is used to perform processing for establishing secure communication. The process of establishing secure communication is a communication start session in which a predetermined process is performed at the start of secure data communication between devices. As described in detail below, the process of establishing secure communication according to this embodiment is a communication initiation session that can use the feature of: near field communication is limited to a narrower range than known processes of establishing secure communication in order to further improve security.

Specifically, in the communication system according to this embodiment, when data communication is performed between the devices 10 having the secure communication function installed, both of the devices 10 having the secure communication function installed use short-range communication such as near field communication to perform processing of establishing secure communication before data communication is started. For example, in the process of establishing secure communication, a session key is shared with a communicating party, and short-range communication is switched to, for example, using bluetooth before data communication is startedLong distance communication.

With the above-described structure, the process of establishing secure communication is performed in advance in short-range communication before starting data communication, and it is possible to prevent confidential information such as a session key from being intercepted, so as to securely perform long-distance data communication.

In the case of Bluetooth (Bluetooth) communication, which is one type of long-distance communication according to this embodiment, the device 10 with the secure communication function mounted thereon can transmit data to another device 10 with the secure communication function mounted thereon, which is about 10m away from the original device 10 with the secure communication function mounted thereon. Therefore, if the device 10 mounted with the secure communication function attempts to perform the process of establishing secure communication in the long-distance communication, there is a possibility that data is intercepted by a third party within the communication area.

A secure communication device 20 acting as an initiator according to one embodiment will now be described with reference to fig. 2. Fig. 2 is a block diagram schematically showing a secure communication apparatus according to this embodiment.

As shown in fig. 2, the secure communication device 20 according to this embodiment includes an active communication unit 101 capable of near field communication, an asymmetric key generator 102, a decryptor 103, a long-distance communication unit 104, an encryptor/decryptor 105, and a switching unit 111.

The secure communication device 20 is provided inside or outside the device 10 in which the secure communication function is installed. The device 10 mounted with the secure communication function can establish data communication with an external device by using the communication function of the secure communication device 20.

The active communication unit 101 is an initiator capable of the above-described near field communication, and generates an electromagnetic wave for a passive communication unit as a target as described below. An Identifier (ID) used in short-range communication or long-range communication is assigned in advance and stored in the active communication unit 101. As shown in fig. 2, an ID "a" (ID a) is assigned to the active communication unit 101. The ID is not limited to being stored in the active communication unit 101, and may be stored in any block (as long as the block has a storage device). Further, the ID assigned to the active communication unit 101 is not limited to the ID a, and any ID may be assigned to the active communication unit 101.

The asymmetric key generator 102 generates an asymmetric key as a pair of an encryption key and a decryption key. Plaintext (data) encrypted with an encryption key (sometimes referred to hereinafter as a public key) can only be decrypted with a decryption key (sometimes referred to hereinafter as a private key) that is half of the generated key pair.

Among the keys generated by the asymmetric key generator 102 as the initiator, the encryption key is transmitted to the passive communication unit 106 as the target, and is used as the encryption key when transmitting the session key. The passive communication unit 106 and the session key will be described below.

The encryption and decryption keys generated by asymmetric key generator 102 are based on a public key cryptosystem such as the Rivest Shamir Adleman (RSA) cryptosystem, elliptic curve cryptosystem, or ElGamal cryptosystem. To verify the validity of the generated encryption key, a digital certificate conforming to an international standard such as x.509 may be transmitted together with the encryption key through, for example, a Public Key Infrastructure (PKI).

Although the asymmetric key generator 102 according to this embodiment generates an encryption key and a decryption key that are asymmetric to each other, the present invention is not limited to this case. For example, the asymmetric key generator 102 may generate an encryption key and a decryption key that are symmetric to each other (the encryption key and the decryption key are sometimes collectively referred to as a common key).

The decryptor 103 decrypts encrypted data, such as an encrypted session key, received by the active communication unit 101, using the decryption key generated by the asymmetric key generator 102. When the received encrypted data is an encrypted session key, the encrypted session key is decrypted to a session key that is used as a common key for encryption and decryption in communication with long-range communication unit 104 as described below. The encryption and decryption using the public key is based on a key cryptosystem, and has a processing speed hundreds to thousands times higher than the encryption and decryption using a public key or a private key. Therefore, encryption and decryption using a common key have a low processing load on the device.

Long-range communication unit 104 has a function of transmitting and receiving data in long-range communication using, for example, Bluetooth (Bluetooth). When transmitting data in the long-distance communication, it is necessary to specify an ID (for example, ID B) of a communication party assigned in advance and transmit the specified ID.

Encryptor/decryptor 105 decrypts the data received by long-distance communication unit 104 with the session key decrypted by decryptor 103. Alternatively, the encryptor/decryptor 105 encrypts data to be transmitted from the device 10 mounted with the secure communication function to another device 10 mounted with the secure communication function. The encrypted data is transmitted to the outside through the long-distance communication unit 104.

The switching unit 111 controls the operation of the active communication unit 101 and the long-distance communication unit 104 to switch the communication devices in response to an external response. For example, when the decryptor 103 returns a response indicating that the encrypted session key has been decrypted, the switching unit 111 controls the communication functions of the active communication unit 101 and the long-distance communication unit 104 so as to switch from short-range communication to long-distance communication (handover). Switching between short-range communication and long-range communication according to this embodiment will be described below.

A secure communication device 22 according to an embodiment will now be described with reference to fig. 3. Fig. 3 is a block diagram schematically showing the structure of the secure communication apparatus according to this embodiment.

As shown in fig. 3, secure communication device 22 according to this embodiment includes passive communication unit 106 capable of near field communication, encryptor 107, random number generator 108, long-distance communication unit 109, encryptor/decryptor 110, and switching unit 112.

As with the secure communication device 20 described above, the secure communication device 22 is provided inside or outside the device 10 in which the secure communication function is installed.

The passive communication unit 106 shown in fig. 3 is a target capable of near field communication as described above, and can respond to an electromagnetic wave transmitted from an initiator. The passive communication unit 106 may receive an electromagnetic wave from the initiator to generate an electromagnetic wave, and may return the generated electromagnetic wave.

An Identifier (ID) used in short-range communication or long-range communication is assigned in advance and stored in the passive communication unit 106. As shown in fig. 3, an ID "B" (ID B) is assigned to the passive communication unit 106. The ID is not limited to being stored in the passive communication unit 106, and may be stored in any block (as long as the block has a storage device). Further, the ID assigned to the passive communication unit 106 is not limited to the ID B, and any ID may be assigned to the passive communication unit 106.

The encryptor 107 encrypts generated data such as a session key using an encryption key transmitted from the active communication unit 101 as an initiator and received by the passive communication unit 106 as a target, and supplies the generated encrypted data to the passive communication unit 106.

The random number generator 108 randomly generates a random number having a predetermined number of digits. The generated random number is used as a bit pattern of the session key (sometimes referred to as a random number hereinafter). Because the bit pattern is a randomly generated random number, the bit pattern of the session key is less likely to be guessed by a third party.

Although the random number generator 108 according to this embodiment is, for example, a circuit including hardware that performs sampling for a high-frequency oscillator circuit to generate a true random number, the random number generator 108 is not limited to such a circuit. For example, the random number generator 108 may be a computer program that includes one or more modules that generate pseudo-random numbers based on a seed of a bit pattern as input.

Since the long-distance communication unit 109, the encryptor/decryptor 110, and the switching unit 112 according to this embodiment have substantially the same structures as the long-distance communication unit 104, the encryptor/decryptor 105, and the switching unit 111 shown in fig. 2, respectively, detailed descriptions thereof are omitted here.

Although in the above-described embodiment, the secure communication device 20 and the secure communication device 22 are separated from each other, the present invention is not limited to this case. For example, the secure communication device 20 and the secure communication device 22 (initiator and target) may be integrated into one device.

The active communication unit 101 according to this embodiment will now be described with reference to fig. 4. Fig. 4 is a block diagram schematically showing the structure of an active communication unit according to this embodiment. Since the passive communication unit 106 shown in fig. 3 is configured in substantially the same manner as the active communication unit 101, a detailed description of the passive communication unit 106 is omitted here.

As shown in fig. 4, the active communication unit 101 according to this embodiment includes an antenna 301, a receiver 303, a demodulator 305, a decoder 307, a data processor 309, an encoder 311, a selector 313, an electromagnetic wave outputter 315, a modulator 317, a load modulator 319, a controller 321, and a power supply 323.

The antenna 301 is a closed loop winding, and outputs an electromagnetic wave in response to a change in current flowing through the winding. A change in the magnetic flux through the windings acting as the antenna 301 causes a current to flow through the antenna 301.

The receiver 303 receives the current flowing through the antenna 30, performs at least tuning and detection, and supplies the signal to the demodulator 305. The demodulator 305 demodulates a signal provided from the receiver 303 and provides the demodulated signal to the decoder 307. The decoder 307 decodes, for example, a manchester code, which is a signal supplied from the demodulator 305, and supplies data resulting from the decoding to the data processor 309.

The data processor 309 performs predetermined processing based on the data supplied from the decoder 307. The data processor 309 also provides data to be transmitted to other devices to the encoder 311.

The encoder 311 encodes the data supplied from the data processor 309 into, for example, a manchester code, and supplies the encoded data to the selector 313. The selector 313 selects either the modulator 317 or the load modulator 319, and supplies the signal supplied from the encoder 311 to the selected modulator.

The selector 313 selects either the modulator 317 or the load modulator 319 under the control of the controller 321. If the communication mode is the active mode or if the communication means is the passive mode and the active communication unit 101 is the initiator, the controller 321 controls the selector 313 so as to select the modulator 317. If the communication mode is the passive mode and the active communication unit 101 is the target, the controller 321 controls the selector 313 so as to select the load modulator 319.

Therefore, in the case where the communication mode is the passive mode and the active communication unit 101 is the target, the signal output from the encoder 311 is supplied to the load modulator 319 through the selector 313. In contrast, in other cases, the signal output from the encoder 311 is supplied to the modulator 317 through the selector 313.

The electromagnetic wave outputter 315 applies a current to the antenna 301 that causes the antenna 301 to emit a carrier wave (an electromagnetic wave corresponding to the carrier wave) having a predetermined frequency. The modulator 317 modulates a carrier wave, which is a current supplied from the electromagnetic wave outputter 315 and flowing through the antenna 301, according to a signal supplied from the selector 313. The antenna 301 emits an electromagnetic wave generated by modulation of a carrier wave in accordance with data supplied from the data processor 309 to the encoder 311.

The load modulator 319 changes the impedance appearing when the winding is externally regarded as the antenna 301 according to the signal supplied from the selector 313. If another device outputs an electromagnetic wave, which is a carrier wave, to form an RF field (magnetic field) around the antenna 301, the impedance that appears when the winding is considered as the antenna 301 changes to change the RF field around the antenna 301. Accordingly, the carrier wave, which is an electromagnetic wave output from another device, is modulated according to the signal supplied from the selector 313, and the data supplied from the data processor 309 to the encoder 311 is transmitted to another device that outputs the electromagnetic wave.

The modulator 317 and the load modulator 319 employ, for example, Amplitude Shift Keying (ASK) as a modulation method. However, the modulation method employed in the modulator 317 and the load modulator 319 is not limited to ASK. Phase Shift Keying (PSK), Quadrature Amplitude Modulation (QAM), or other methods may be employed as the modulation method in the modulator 317 and the load modulator 319. The degree of modulation is not limited to a predetermined value such as a value from 8% to 30%, 50%, or 100%, and may be set to a preferred value.

The controller 321 controls each block in the active communication unit 101. The power supply 323 supplies the required energy to each block in the active communication unit 101. Referring to fig. 4, a wiring indicating control of each block in the active communication unit 101 by the controller 321 and a wiring for supplying power to each block in the device 1 in which the secure communication function is installed by the power supply 323 are omitted for simplicity.

Although the decoder 307 and the encoder 311 process the manchester code in this embodiment, the present invention is not limited to the above case. The decoder 307 and encoder 311 may select a type of code from a plurality of types of codes to process the selected type of code, wherein the plurality of types of codes include not only manchester codes but also modified mirror and non-return to zero (NRZ) codes.

If the active communication unit 101 operates in the passive mode only as a target, the selector 313, the electromagnetic wave outputter 315, and the modulator 317 may be eliminated from the active communication unit 101. In this case, the power supply 322 generates energy from, for example, external electromagnetic waves received by the antenna 301.

The secure communication function-installed device 10 according to this embodiment is configured to be capable of communication according to one or more communication protocols in addition to being capable of near field communication as described above. Thus, near field communication is one of the communications according to the plurality of communication protocols. These communication protocols include ISO/IEC (international organization for standardization/international electrotechnical commission) 14443 defining communication with the IC card, ISO/IEC 15693 defining communication with the RF tag (radio frequency tag), Bluetooth (Bluetooth), and WLAN or other communication protocols in addition to NFC.

A series of communication processes in the communication system 100 according to an embodiment will now be described with reference to fig. 5. Fig. 5 is a sequence diagram schematically showing a series of communication processes in the communication system according to this embodiment.

As shown in fig. 5, when the device 10a with the secure communication function installed communicates with the device 10b with the secure communication function installed, it is necessary to establish secure communication in short-range communication. Therefore, the device 10a with the secure communication function installed is moved in advance into a range in which the device 10a with the secure communication function installed can establish short-range communication with the device 10b with the secure communication function installed.

A case will now be described with reference to fig. 6 in which the device 10a mounted with the secure communication function and the device 10b mounted with the secure communication function according to this embodiment are located within a range in which short-range communication can be established therebetween. Fig. 6 is a diagram illustrating short-range communication between the device 10a mounted with the secure communication function and the device 10b mounted with the secure communication function according to this embodiment.

As shown in fig. 6, when the secure communication function-mounted device 10a is moved to a range of about 10cm away from the secure communication function-mounted device 10b, both the secure communication function-mounted devices 10a and 10b are located within a range in which short-range communication can be established. Secure communication is established between the devices 10a and 10b mounted with the secure communication function to realize long-distance data communication. Although the device 10a in fig. 6 in which the secure communication function is installed is a mobile phone and the device 10b in fig. 6 in which the secure communication function is installed is a headset for the mobile phone, the devices 10a and 10b in which the secure communication function is installed are not limited to this example. A headset having a speaker and a microphone transmits and receives audio data to and from a mobile telephone so that direct communication with the mobile telephone can be achieved even when a user does not directly place the mobile telephone near one ear.

A process of establishing secure communication in short-range communication between the devices 10 mounted with the secure communication function according to this embodiment will now be described with reference to fig. 7 and 8. Fig. 7 and 8 are diagrams illustrating a process of establishing secure communication in short-range communication between the devices 10 mounted with the secure communication function according to this embodiment.

As shown in fig. 7, there are provided a device 10a with a secure communication function installed as an initiator, and devices 10b and 10a with secure communication functions installed as targets. The device 10a mounted with the secure communication function emits electromagnetic waves to the outside.

The device 10a mounted with the secure communication function can detect a change of 1% or more in the magnetic field generated by itself. Specifically, if a change of 1% or more in the magnetic field is caused by the external secure communication function-mounted device 10, the secure communication function-mounted device 10a can determine that the change corresponds to a response from the external secure communication function-mounted device 10.

As shown in fig. 7, the device 10b mounted with the secure communication function can absorb 4% of the magnetic field (or electromagnetic wave) generated by the device 10a mounted with the secure communication function. The device 10b mounted with the secure communication function may reflect the absorbed magnetic field so as to change 1% or more of the generated magnetic field in response to the device 10a mounted with the secure communication function.

In other words, the device 10b with the secure communication function mounted shown in fig. 7 is located within a range of, for example, about 10cm from the device 10a with the secure communication function mounted. Within this range, short-range communication can be established between the device 10a with the secure communication function installed and the device 10b with the secure communication function installed.

The device with the secure communication function 10c can absorb only 0.5% of the magnetic field generated by the device with the secure communication function 10 a. Even if the device 10c with the secure communication function attached reflects all of the absorbed magnetic field, the device 10a with the secure communication function attached cannot detect a change in the magnetic field. Therefore, the device 10c with the secure communication function mounted cannot respond to the device 10a with the secure communication function mounted.

In other words, the device 10c mounted with the secure communication function is located in a range in which short-range communication cannot be established with the device 10a mounted with the secure communication function.

Since the short-range communication according to this embodiment can only be established within a limited range, the risk of data being intercepted is reduced compared to communication devices having a wider communication area, e.g. with a radius of 10 m.

Next, as shown in fig. 8(a), in order to establish secure communication according to this embodiment, the device 10a mounted with the secure communication function generates an encryption key and a decryption key corresponding to the encryption key.

The encryption key is transmitted from the device 10a mounted with the secure communication function to the outside through a magnetic field. Therefore, as shown in fig. 8(a), the device 10b with the secure communication function installed and the device 10c with the secure communication function installed can receive data regardless of whether they are within a range in which short-range communication can be established.

However, as shown in fig. 8(b), as described above with reference to fig. 7, even if the secure communication function-installed device 10c receives the encryption key, the secure communication function-installed device 10c cannot respond to the secure communication function-installed device 10 a. Therefore, only the device 10b having the secure communication function installed can encrypt the session key generated by itself and return the generated session key to the device 10a having the secure communication function installed.

As shown in fig. 8(c), even if the secure communication function-mounted device 10a decrypts the received encrypted session key, encrypts data with the session key, and transmits the encrypted data to the secure communication function-mounted device 10c, and even if the secure communication function-mounted device 10c can receive the encrypted data, the secure communication function-mounted device 10c cannot decrypt the encrypted data because there is no session key for decrypting the encrypted data.

Therefore, since there is no danger that encrypted data is intercepted and decrypted if the device 10 in which the secure communication function is installed is located within a range in which short-range communication cannot be established, it is possible to establish communication securely. Furthermore, the risk that another device 10 with a secure communication function installed is located within a range in which short-range communication can be established is very low. This is because the area in which short-range communication can be established is limited in space and under the control of the user.

The session key according to this embodiment is a one-time key used in long-distance data communication. Thus, as with the one-time password, a new session key is generated for each predetermined time or for each communication session.

This is sufficient to keep the session key that was first generated using the random number secret until a subsequent session key is newly generated. Therefore, it is sufficient to let the encryption key generated by the asymmetric key generator 102 have a length that cannot be decrypted in a short time (for example, one second) before generating a session key and sharing the session key between the devices 10 in which the secure communication function is installed. In other words, the process of establishing secure communication must be ended in a short period of time so as not to provide the third party with sufficient time to decrypt the first session key as confidential information. Since a secret key having a higher security strength is generated at a subsequent timing and the first session key is removed even if the first session key is intercepted, the first session key is not in danger of being misused.

Referring back to fig. 5, first, in step S501, the active communication unit 101 in the device 10a in which the secure communication function is installed performs polling (inquiry processing). In step S502, the passive communication unit 106 in the secure communication function-mounted device 10b receives the polling, and transmits a response to the polling to the active communication unit 101.

It is assumed that the device 10a with the secure communication function installed and the device 10a with the secure communication function installed shown in fig. 5 are located within a range in which short-range communication can be established as described above.

The active communication unit 101 receives the response transmitted from the passive communication unit 106 in response to the polling, generates an encryption key and a decryption key, and transmits the encryption key and an ID (e.g., NFC ID) assigned to the active communication unit 101 (S503). As described above with reference to fig. 2 and 3, the NFC ID corresponds to, for example, "ID a" or "ID B".

After the passive communication unit 106 receives the encryption key and the ID, the random number generator 108 randomly generates a random number (S504). As described above, the generated random number is used as a session key.

The encryptor 107 encrypts the generated session key with the encryption key that has already been received (S505). The encrypted session key is transmitted to the active communication unit 101 together with an ID (e.g., NFC ID) assigned to the passive communication unit 106.

After the active communication unit 101 receives the encrypted session key and the ID, the decryptor 103 decrypts the encrypted session key using the generated decryption key (S507) to generate a session key.

The active communication unit 101 can identify the passive communication unit 106 (the device 10b with the secure communication function mounted) as the communication party based on the ID received from the passive communication unit 106. The passive communication unit 106 can identify the active communication unit 101 (the device 10a with the secure communication function installed) as the communication party based on the ID received together with the encryption key.

The decrypted session key is supplied to the encryptor/decryptor 105, and the ID of the passive communication unit 106 received by the active communication unit 101 is supplied to the long-distance communication unit 104. The ID of the active communication unit 101 received by the passive communication unit 106 is supplied to the long-distance communication unit 109, and the session key generated by the random number generator 108 is supplied to the encryptor/decryptor 110. Therefore, both long-range communication unit 104 and long-range communication unit 109 can recognize the communication party.

After the decryptor 103 decrypts the encrypted session key into a session key (step S507), the switching unit 111 transmits a switching request for requesting switching from short-range communication such as near field communication to long-range communication using, for example, Bluetooth (Bluetooth) (e.g., a request signal requesting communication switching or a medium handover request) to the passive communication unit 106 through the active communication unit 101 (S508).

Bluetooth (Bluetooth) communication has a higher transmission speed, can transmit large-capacity data more quickly and efficiently, and has a wider communication range than near field communication. Thus, it is useful to switch from short-range communication to long-range communication, for example, when the user is calling with a headset without holding the mobile phone.

When this switching request is transmitted, communication information necessary for long-distance communication is exchanged between the devices 10 mounted with the secure communication function, in addition to identification information such as NFC ID that has already been acquired in short-range communication. An example of communication information necessary for long-distance communication is a Bluetooth (Bluetooth) device address that identifies a communication party in long-distance communication.

After receiving the switching request, the passive communication unit 106 transmits a response (e.g., a medium handover response) to the switching request transmitted from the active communication unit 101 to the active communication unit 101 (S509). The active communication unit 101 receives the response.

The device 10a mounted with the secure communication function switches from short-range communication by the active communication unit 101 to long-range communication (handover) using, for example, Bluetooth (Bluetooth) by the long-range communication unit 104 (S511). The device 10b mounted with the secure communication function switches from short-range communication by the passive communication unit 106 to long-range communication (handover) by the long-range communication unit 109 (S510).

Sharing the session key between the secure communication function-installed devices 10a and 10b results in establishing secure communication, and ends short-range communication between the active communication unit 101 and the passive communication unit 106 (S512).

Then, secure data communication is performed between the switched long-range communication unit 104 and the long-range communication unit 109 using the session key shared in short-range communication (S513). For example, the first session key shared in the short-range communication is newly generated each time the session ends. With this structure, it is possible to further improve security as compared with a process of establishing secure communication in long-distance communication. Although a public key based on a public key cryptosystem is used as the session key according to this embodiment, the present invention is not limited to such a session key.

When short-range communication is switched to long-range communication, the long-range communication unit 104 and the long-range communication unit 109 can identify the communication party to perform data communication even if the communication party is not specified by the user.

Since the long-range communication unit 104 and the long-range communication unit 109 can identify the communication parties based on the identification information (for example, NFC ID) of the communication parties that has already been acquired in the short-range communication, the long-range communication unit 104 and the long-range communication unit 109 do not establish data communication with the communication parties other than the communication party identified with the acquired identification information. Therefore, it is possible to prevent incorrect data communication with the wrong communication party.

As described above, when data communication is established between the secure communication function-installed devices 10 in the communication system according to this embodiment, only one secure communication function-installed device 10 that first enters a communication area in which short-range communication can be established can be identified to securely exchange a session key without complicating the setting of secure communication. Further, by switching from short-range communication to long-range communication and using a session key shared in the short-range communication, it is possible to establish secure communication in long-range communication having a wider communication area and a higher communication speed than short-range communication.

Since the communication party (the secure communication function-mounted device 10) of the long-distance communication can be identified by exchanging the session key used in the short-range communication, it is possible to eliminate the danger of establishing data communication with the unspecified secure communication function-mounted device 10, and therefore the communication party can be easily identified so as to establish data communication.

In the process of establishing secure communication in short-range communication, an encryption key sufficient for keeping a session key exchanged between the devices 10 mounted with the secure communication function secret has a key length such as to provide strength to prevent the session key from being recognized by a third party after the encryption key is transmitted and before the session key encrypted with the encryption key is decrypted, the session key is exchanged, and long-range communication is started. Therefore, even when the processing capability, e.g., the computational performance, of each device is not too high, it is possible to efficiently perform the process of establishing secure communication.

It is sufficient to generate an encryption key and a decryption key pair according to this embodiment, if necessary. Since the digital certificate of the key pair or the like is not necessarily required, a complicated process for registering the digital certificate can be omitted.

The series of processes described above may be executed by dedicated hardware or by software. If this series of processes is executed by software, a program in the software is installed in a general-purpose computer or a microcomputer. The program may be stored in advance in a Hard Disk Drive (HDD) included in the computer, or may be stored in advance in a storage device such as a ROM.

The program may be temporarily or permanently stored (recorded) in a removable recording medium such as a flexible disk, a CD-ROM (compact disc read only memory), an MO (magneto optical) disk, a DVD (digital versatile disc), a magnetic disk, or a semiconductor memory, in addition to the HDD or the ROM described above. Such a removable recording medium may be provided as packaged software.

In addition to installing the program from the removable recording medium into the computer, the program may be transmitted from a download site into the computer by wireless communication via an artificial satellite for digital satellite broadcasting, or may be transmitted into the computer by wired communication via a network such as a LAN (local area network) or the internet. The computer receives the program transmitted in the above manner and installs the program into the storage device.

In this description, the processing steps describing the program used by the computer to execute various processes are not necessarily executed chronologically in the order as described in the sequence diagram shown in fig. 5, but may be executed separately or in parallel (including, for example, parallel processing and object processing).

Although wireless communication is contemplated in this embodiment, the present invention is not limited to wireless communication. For example, the present invention is applicable to wired communication or communication in which wireless communication and wired communication are mixed.

While the present invention has been described with reference to the accompanying drawings and what are presently considered to be the preferred embodiments, the invention is not limited to the disclosed embodiments. On the contrary, it is to be understood that the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Although the blocks including the asymmetric key generator 102, the decryptor 103, the encryptor/decryptor 105, and the switching unit 111 in the secure communication device 20 are described as hardware in the above-described embodiment, the present invention is not limited to this example. For example, at least one of the above blocks may be a program including one or more modules or components.

Although the blocks including encryptor 107, random number generator 108, encryptor/decryptor 110, and switching unit 111 in secure communication apparatus 22 are described as hardware in the above-described embodiment, the present invention is not limited to this example. For example, at least one of the above blocks may be a program including one or more modules or components.

Although the case where two devices having a secure communication function installed establish communication is exemplified in the above embodiment, the present invention is not limited to this example. For example, the present invention is applicable to a case where three devices in which a secure communication function is installed establish communication. In this case, one of the three secure communication function-installed devices may serve as an intermediary for relaying data transmitted between the remaining two secure communication function-installed devices.

Although the secure communication device 20 and the secure communication device 22 are separated in the above-described embodiment, the present invention is not limited to this example. For example, the secure communication device 20 and the secure communication device 22 may be integrated as a single device into the device 10 in which the secure communication function is installed.

Industrial applicability

The present invention is applicable to a communication system and a secure communication device capable of transmitting and receiving data by wireless communication.

Claims (6)

1. A communication system comprising a plurality of communication devices,

wherein the first communication device comprises:

a short-range active communication means for transmitting an inquiry signal to a short-range external communication device by electromagnetic waves and waiting for a response to the inquiry signal;

a long-distance communication device capable of communicating by electromagnetic waves in a wider range than a communication area of the short-distance active communication device;

switching means for switching to either the short-range active communication means or the long-range communication means; and

asymmetric key generation means for generating a pair of keys including an encryption key and a decryption key corresponding to the encryption key, the encryption key and the decryption key in the pair of keys being asymmetric with each other,

wherein the second communication device comprises:

short-range passive communication means for receiving the inquiry signal from a short-range external communication device and transmitting a response signal in response to the inquiry signal;

a long-distance communication device capable of communicating by electromagnetic waves in a wider range than a communication area of the short-range passive communication device;

switching means for switching to either the short-range passive communication means or the long-range communication means;

session key generation means for generating a random number and generating a session key using the generated random number; and

encryption means for encrypting the session key,

wherein the short range active communication device transmits the encryption key generated by the asymmetric key generation device to the short range passive communication device upon receiving the response signal from the short range passive communication device;

wherein the second communication device encrypts the session key into an encrypted session key using the encryption key transmitted from the first communication device and transmits the encrypted session key to the short-range active communication means of the first communication device through the short-range passive communication means,

wherein the first communication device decrypts the encrypted session key into the session key using the decryption key and transmits a communication handover request signal for requesting handover to the long-distance communication means and communication using the long-distance communication means to the short-distance passive communication means of the second communication device through the short-distance active communication means, and

wherein the short-range passive communication means transmits a response to the communication switching request signal to the short-range active communication means, and then the first communication device and the second communication device switch to the long-range communication means and perform long-range communication between the long-range communication means using the session key.

2. The communication system as set forth in claim 1,

wherein the short range active communication device transmits identification information assigned to the short range active communication device to the short range passive communication device together with the encryption key; and

wherein the short-range passive communication means transmits the identification information assigned to the short-range passive communication means together with the encrypted session key to the short-range active communication means in order to provide the identification information of the communication party to the long-range communication means provided in the first and second communication devices.

3. A communication device, comprising:

a short-range active communication means for transmitting an inquiry signal to a short-range external communication device by electromagnetic waves and waiting for a response to the inquiry signal;

a long-distance communication device capable of communicating by electromagnetic waves in a wider range than a communication area of the short-distance active communication device;

switching means for switching to either the short-range active communication means or the long-range communication means;

asymmetric key generation means for generating a pair of keys including an encryption key and a decryption key corresponding to the encryption key, the encryption key and the decryption key in the pair of keys being asymmetric with each other,

wherein the short-range active communication means is further for sending the encryption key to the external communication device,

wherein the communication apparatus decrypts an encrypted session key transmitted from the external communication apparatus by short-range communication using the decryption key, and transmits a communication switching request signal for requesting switching to the long-range communication means and performing communication using the long-range communication means to the external communication apparatus through the short-range active communication means, and the communication apparatus switches to the long-range communication means upon receiving a response to the communication switching request signal from the external communication apparatus, so as to perform long-range communication with the external communication apparatus using the session key.

4. The communication device as set forth in claim 3,

wherein the short range active communication means transmits identification information assigned to the short range active communication means to the external communication device together with the encryption key; and

wherein the short-range active communication means receives identification information assigned to the external communication device together with the encrypted session key from the external communication device so as to provide identification information of a communication party to the long-range communication means provided in the communication device and the external communication device.

5. A communication device, comprising:

short-range passive communication means for receiving an inquiry signal from a short-range external communication device and transmitting a response signal in response to the inquiry signal;

a long-distance communication device capable of communicating by electromagnetic waves in a wider range than a communication area of the short-range passive communication device;

switching means for switching to either the short-range passive communication means or the long-range communication means;

session key generation means for generating a random number and generating a session key using the generated random number; and

encryption means for encrypting the session key,

wherein the communication apparatus encrypts the session key into an encrypted session key using an encryption key received by the short-range passive communication means from an external communication apparatus and transmits the encrypted session key to the external communication apparatus through the short-range passive communication means, and receives a communication switching request signal for requesting switching to the long-range communication means and performing communication using the long-range communication means from the external communication apparatus through the short-range passive communication means, then transmits a response to the communication switching request signal to the external communication apparatus through the short-range passive communication means, and then switches to the long-range communication means to perform long-range communication with the external communication apparatus using the session key.

6. The communication device as set forth in claim 5,

wherein the short-range passive communication device receives identification information assigned to the external communication apparatus together with the encryption key; and

wherein the short-range passive communication means provides the identification information assigned to the short-range passive communication means together with the encrypted session key to the external communication apparatus so as to provide the identification information of the communication party to the long-range communication means and the external communication apparatus provided in the communication apparatus.