Data transceiving system and data transceiving method

The present invention relates to a data transmission / reception system, and more particularly to securing a data communication path with improved confidentiality.

Patent Document 1 discloses a technique for distributing music data to a mobile phone.

<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2004-310054</text></patcit>

<p> Even if you try to play the music data delivered to the mobile phone on a device with a higher acoustic effect, for example, car audio, instead of playing it on the mobile phone as it is, the input terminal to the car audio will be output to the mobile phone. You cannot connect without terminals. Further, even if such an input terminal is provided in the kari, the connection work is complicated.</p><p> Therefore, the inventor has considered providing a wireless LAN communication unit in the car audio and transferring the music data from the wireless LAN communication unit of the mobile phone to the car audio.</p><p> However, in this case, if another car near the car equipped with the car audio is also equipped with a wireless LAN communication unit of the same standard, music data may be transmitted to the other car as well. .. In order to prevent such a problem, it is conceivable to encrypt the data, but if the encryption key is transmitted over the wireless LAN communication path, confidentiality cannot be ensured, while it is manually encrypted. Setting the key is complicated.</p><p> Such a problem becomes a problem not only in the case of wireless LAN but also in the case of transmitting data by the Internet standard.</p><p> An object of the present invention is to provide a data transmission / reception system in which only a specific destination can receive data in a reproducible state.</p>

<p> 1) The data transmission / reception system according to the present invention includes A) a first terminal for transmitting data to be transmitted, and B) a second terminal for receiving data to be transmitted transmitted from the first terminal. In the system, C) the first terminal is c1) a transmission target data storage means for storing the transmission target data, c2) an encryption means for encrypting the transmission target data using an encryption key, c3). The main transmission means for transmitting the encrypted encrypted transmission target data, c4) the sub transmission / reception means for transmitting / receiving data on a transmission path different from the main transmission means, D) the second terminal is d1). Main receiving means for receiving encrypted transmission target data transmitted from the first terminal, d2) Decrypting means for decrypting the encrypted transmission target data using a decryption key, d3) Of the first terminal A sub-transmission / reception means and a sub-transmission / reception means for transmitting data are provided. E) The sub-transmission / reception means of the first terminal is used for the sub-transmission / reception means of the second terminal before transmitting the data to be transmitted. To send Therefore, the information for decrypting the encrypted transmission target data is transmitted between the sub-transmission means, and is not transmitted in the main transmission line formed by the main transmission means and the main reception means. As a result, transmission with ensured confidentiality can be easily performed.</p><p> 2) The data transmission / reception system according to the present invention includes 1) a first terminal for transmitting data to be transmitted, and 2) a second terminal for receiving data to be transmitted from the first terminal. In the system, 3) between the first terminal and the second terminal, in addition to the main transmission line for transmitting the data to be transmitted, a transmission distance that is more limited than that of the main transmission line. Alternatively, a sub-transmission line with a limited transmission direction is provided, and 4) Confidentiality release information for receiving the data to be transmitted on the second terminal to ensure confidentiality transmitted on the main transmission line. Is determined between the first terminal and the second terminal using the sub-transmission line before the transmission of the transmission target data, and the transmission target data is transmitted using the determined confidentiality release information. It transmits and transmits the confidentiality assurance transmission target data.</p><p> Therefore, the confidentiality release information can be determined between the first terminal and the second terminal without using the main transmission line. This makes it possible to easily transmit through the main transmission line in which confidentiality is ensured.</p><p> 3) The first terminal according to the present invention is a first terminal that transmits data to be transmitted to a second terminal, and 1) transmits the data to be transmitted to and from the second terminal. In addition to the main transmission line, a sub-transmission line having a shorter transmissible distance or a limited transmission direction than the main transmission line is provided, and 2) confidentiality transmitted on the main transmission line. Confidentiality release information for receiving the secured transmission target data at the second terminal is determined with the second terminal using the sub-transmission line before the transmission of the transmission target data. , The confidentiality assurance transmission target data is transmitted. Therefore, the confidentiality release information can be determined with the second terminal without using the main transmission line. On the other hand, the main transmission line transmits data to be transmitted to ensure confidentiality. This makes it possible to easily transmit through the main transmission line in which confidentiality is ensured.</p><p> 4) The second terminal according to the present invention is a second terminal that receives transmission target data transmitted from the first terminal, and the transmission target data is transmitted to and from the first terminal. In addition to the main transmission line for transmission, an auxiliary transmission line having a transmission range or a limited transmission direction is provided in the main transmission line from the first terminal. Ensuring confidentiality to be transmitted Confidentiality release information for receiving transmission target data is determined and determined with the first terminal using the sub-transmission line before transmission of the transmission target data. Receives the transmission target data transmitted using the confidentiality release information. Therefore, the confidentiality release information can be determined with the first terminal without using the main transmission line. On the other hand, the main transmission line transmits data to be transmitted to ensure confidentiality. This makes it possible to easily transmit through the main transmission line in which confidentiality is ensured.</p><p> 5) In the first terminal or the second terminal according to the present invention, the confidentiality release information is content decryption information by encryption processing. Therefore, even if it is received by another device, the content cannot be deciphered.</p><p> 6) In the first terminal or the second terminal according to the present invention, the confidentiality release information is the reception restriction release information for releasing the reception restriction. Therefore, reception by another device can be restricted.</p><p> 7) In the data transmission / reception system according to the present invention, the main transmission line is a transmission line for performing Internet communication by HTTP. Therefore, even if the Internet communication has low confidentiality, the data to be transmitted can be transmitted while ensuring confidentiality.</p><p> 8) In the data transmission / reception system according to the present invention, data provided with 1) a first terminal for transmitting transmission target data, and 2) a second terminal for receiving transmission target data transmitted from the first terminal. It is a transmission / reception system, and 3) between the first terminal and the second terminal, in addition to the main transmission line for transmitting the data to be transmitted, more limited transmission than the main transmission line is possible. A sub-transmission line with a distance or a limited transmission direction is provided. 4) Confidentiality assurance transmitted on the main transmission line Confidentiality release information for receiving transmission target data is transmitted to the transmission target data. Is determined between the first terminal and the second terminal using the sub-transmission line, and 5) confidentiality is ensured between the first terminal and the second terminal. Transmit the data to be transmitted. This makes it possible to easily transmit and receive via the main transmission line in which confidentiality is ensured.</p><p> 9) The first terminal according to the present invention is a first terminal that transmits data to be transmitted to a second terminal, and is a main unit that transmits the data to be transmitted to and from the second terminal. In addition to the transmission line, a sub-transmission line having a transferable distance or a limited transmission direction than the main transmission line is provided, and the main transmission line is used to connect to the second terminal. When the confidentiality of the data to be transmitted is secured and transmitted, the confidentiality ensuring information used for ensuring the confidentiality is transmitted by using the sub-transmission line before the transmission of the data to be transmitted. The confidentiality of the data to be transmitted is ensured by exchanging with the terminal of the above, and the confidentiality of the data to be transmitted is secured, and the data is transmitted to the second terminal through the main transmission line, and is transmitted from the second terminal. When the transmission target data whose confidentiality is ensured by using the confidentiality assurance information is transmitted on the main transmission line, it is received based on the confidentiality assurance information. This makes it possible to easily transmit and receive via the main transmission line in which confidentiality is ensured.</p><p> 10) The data transmission / reception system according to the present invention is a second computer that 1) transmits data to be transmitted, and 2) receives data to be transmitted from the first computer on a first transmission path. Computer, 3) The second computer is provided with a third computer that transmits data over a second transmission line with a more limited transmittable distance or a limited transmission direction than the first transmission line. It is a data transmission / reception system, and 4) the second computer provides confidentiality release information for receiving data to be transmitted for ensuring confidentiality transmitted from the first computer on the first transmission path. Receive from the third computer via the second transmission line. Therefore, only the second computer that receives the confidentiality release information from the third computer that transmits data on the second transmission line having a limited transferable distance or a limited transmission direction ensures the confidentiality. The data to be transmitted can be received.</p><p> 11) The second computer according to the present invention is a second computer that receives data to be transmitted from the first computer, and is a first transmission that transmits the data to be transmitted to and from the first computer. A path is provided, and a second transmission line different from the first transmission line to and from the third computer, and a transmission range or limit that is more limited than that of the first transmission line. A second transmission line having a transmission direction is provided, and confidentiality release information for receiving the confidentiality assurance transmission target data transmitted from the first computer on the first transmission line is provided. , Receive from the third computer via the second transmission line. Therefore, only the second computer that receives the confidentiality release information from the third computer that transmits data on the second transmission line having a limited transferable distance or a limited transmission direction ensures the confidentiality. The data to be transmitted can be received.</p><p> 12) The data transmission / reception system according to the present invention transmits / receives data between a first terminal for transmitting transmission target data and a second terminal for receiving transmission target data transmitted from the first terminal. The method is as follows: 1) In addition to the main transmission line for transmitting the data to be transmitted between the first terminal and the second terminal, a transmission distance that is more limited than that of the main transmission line or A sub-transmission line with a limited transmission direction is provided, and 2) confidentiality release information for receiving the data to be transmitted on the second terminal for ensuring confidentiality transmitted on the main transmission line is transmitted. Before transmitting the target data, the sub-transmission line is used to determine between the first terminal and the second terminal, and the confidentiality is ensured from the first terminal to the second terminal. Transmit the data to be transmitted. Therefore, the confidentiality release information can be determined between the first terminal and the second terminal without using the main transmission line. This makes it possible to easily transmit through the main transmission line in which confidentiality is ensured.</p><p> 13) The data transmission method according to the present invention is a data transmission method for transmitting data to be transmitted from a first terminal to a second terminal, and 1) between the first terminal and the second terminal. In addition to the main transmission line for transmitting the data to be transmitted, a sub-transmission line having a transmission range or a limited transmission direction is provided in the main transmission line, and 2) the main transmission line. Ensuring confidentiality to be transmitted Confidentiality release information for receiving transmission target data at the second terminal is transmitted to the first terminal using the sub-transmission line before transmission of the transmission target data. It is determined with the second terminal, and the confidentiality assurance transmission target data is transmitted from the first terminal to the second terminal. Therefore, the confidentiality release information can be determined between the first terminal and the second terminal without using the main transmission line. This makes it possible to easily transmit through the main transmission line in which confidentiality is ensured.</p><p> 14) The data receiving method according to the present invention is a method of receiving transmission target data transmitted from the first terminal at the second terminal, and 1) the first terminal and the second terminal. In between, in addition to the main transmission line for transmitting the data to be transmitted, a sub-transmission line having a transmission range limited or a transmission direction limited to that of the main transmission line is provided, and 2) the main transmission line is provided. The confidentiality release information for receiving the confidentiality release target data to be transmitted by the second terminal is transmitted to the first terminal by using the sub-transmission line before the transmission of the transmission target data. And the second terminal. Therefore, the confidentiality release information can be determined between the first terminal and the second terminal without using the main transmission line. This makes it possible to easily transmit through the main transmission line where confidentiality is ensured. 15) The program according to the present invention is a program for a first terminal that transmits data to be transmitted to a second terminal, and is a program for causing the first terminal to execute the following steps. 1) In addition to the main transmission line for transmitting the data to be transmitted, a sub-transmission line having a transmission range limited or a transmission direction limited to that of the main transmission line is provided between the second terminal and the main transmission line. Steps to be provided, 2) Ensuring confidentiality transmitted on the main transmission line The confidentiality release information for receiving the transmission target data on the second terminal is transmitted to the sub-transmission before the transmission of the transmission target data. A step of determining to and from the second terminal using a road. Therefore, the confidentiality release information can be determined between the first terminal and the second terminal without using the main transmission line. This makes it possible to easily transmit through the main transmission line where confidentiality is ensured. 16) The program according to the present invention is a program for a second terminal for receiving transmission target data transmitted from the first terminal on the second terminal, and the following steps are applied to the second terminal. A program to execute. 1) In addition to the main transmission line for transmitting the data to be transmitted, a sub-transmission line having a transmission range limited or a transmission direction limited to that of the main transmission line is provided between the first terminal and the main transmission line. Steps to be provided, 2) Ensuring confidentiality transmitted from the first terminal on the main transmission line Confidentiality release information for receiving the transmission target data is transmitted to the sub transmission line before the transmission of the transmission target data. To determine with and from the first terminal using. Therefore, the confidentiality release information can be determined between the first terminal and the second terminal without using the main transmission line. This makes it possible to easily transmit through the main transmission line where confidentiality is ensured. In addition, in this specification, "confidentiality release information" includes not only information for canceling reception restriction but also information for releasing confidentiality for reproduction of received data without limiting reception itself. "Confidentiality assurance information" includes not only encrypted information that prevents the received data from being reproduced even if it can be received, but also information for restricting reception. For example, "ensuring the confidentiality of the data to be transmitted". This means not only when changing the content of data such as encryption, but also when concealing the data transmission protocol to ensure confidentiality, or when only a registered terminal can transmit data. Also includes.</p>

1. Functional block diagram Figure 1 shows the overall configuration of the data transmission / reception system 10 according to the present invention. The data transmission / reception system 10 includes a first terminal 1 and a second terminal 11.

The first terminal 1 stores transmission target data storage means 3 for storing transmission target data, encryption means 4 for encrypting stored transmission target data using an encryption key 4, and encrypted transmission target data. It is provided with a main transmitting means 5 for transmitting data and an auxiliary transmitting / receiving means 6 for transmitting / receiving data on a transmission path different from that of the main transmitting means 5. Further, the sub-transmission / reception means 6 receives a decryption key for decrypting the encrypted transmission target data from the encryption means 4, and transmits the decryption key to the second terminal 11 before transmitting the encrypted transmission target data.

The second terminal 11 is a main receiving means 15 for receiving encrypted transmission target data transmitted from the first terminal 1, a decoding means 14 for decrypting the encrypted transmission target data using a decryption key, and a second terminal. The sub-transmission / reception means 16 for transmitting data to / from the sub-transmission / reception means 6 of the terminal 1 of 1 is provided.

In this way, by passing the decryption key used for decrypting the encrypted transmission target data between the other sub-transmission means 6 and 16 instead of between the main transmission means 5 and the main receiving means 15 that transmit the encrypted transmission target data. , Confidentiality in the main transmission line formed by the main transmission means 5 and the main reception means 15 can be ensured.

2. Hardware configuration 2.1 Hardware configuration of the first terminal The hardware configuration when the data transmission / reception system 10 shown in Fig. 1 is realized by a mobile phone and car audio will be described.

FIG. 2 shows an example of the hardware configuration of a mobile phone that functions as a first terminal. The mobile phone 21 includes a CPU 23, a memory 27, a telephone communication unit 24, a microphone 25, an audio unit 26, a speaker 28, an encryption processing unit 31, an operation unit 29, a wireless LAN communication board 33, an infrared communication board 35, a liquid crystal display unit 30, and a liquid crystal display unit 30. It has a bus line 39. The CPU 23 controls each part via the bus line 39 according to the program stored in the memory 27. The processing by such a program will be described later.

Although the above program is stored in the memory in advance, it may be received from the wireless LAN communication board 33 or the like and stored in the memory 27. In this case, not only the format that can be directly executed by just installing it as it is, but also the one that needs to be converted to another form (for example, decompressing the data-compressed one), and other module parts. It may be executed in combination with.

The telephone communication unit 24 communicates with a general mobile phone. Detailed description will be omitted. Based on the instruction from the CPU 23, the audio unit 26 reproduces, for example, the music data stored in the memory 27, and outputs the music data from the speaker 28. The encryption unit 31 performs encryption processing of the given data by using the encryption key stored in the memory 27 based on the instruction from the CPU 23.

Various instructions are input from the user to the operation unit 29. The wireless LAN communication board 33 performs wireless LAN communication. The infrared communication board 35 performs infrared communication. The liquid crystal display unit 30 displays the display data instructed by the CPU 23.

2.2 Hardware configuration of the second terminal Figure 3 shows an example of the hardware configuration of the car audio 121 that functions as the second terminal.

The car audio 121 includes a CPU 123, a memory 127, an audio unit 126, a speaker 128, a decoding processing unit 131, an operation unit 129, a wireless LAN communication board 133, an infrared communication board 135, a liquid crystal display unit 130, and a bus line 139. The CPU 123 controls each part via the bus line 139 according to the program stored in the memory 127. The processing by such a program will be described later.

Although the above program is stored in the memory 127 in advance, it may be received from the wireless LAN communication board 133 or the like and stored in the memory 127. In this case, not only the format that can be directly executed by just installing it as it is, but also the one that needs to be converted to another form (for example, decompressing the data-compressed one), and other module parts. It may be executed in combination with.

The audio unit 126 performs audio processing for car audio. For example, based on the instruction from the CPU 123, the music data stored in the memory 127 is played back, and the music data is output from the speaker 128. In the present embodiment, the music data transmitted by streaming can also be reproduced. The decoding processing unit 131 decrypts the given data by using the decoding key stored in the memory 127 based on the instruction from the CPU 123.

Various instructions are input from the user to the operation unit 129. The wireless LAN communication board 133 performs wireless LAN communication. The infrared communication board 135 performs infrared communication. The liquid crystal display unit 130 displays the display data instructed by the CPU 123.

3. Program The data transmission process between the mobile phone 21 and the car audio 121 will be explained using Fig. 4. In this example, a case where the music data stored in the mobile phone 21 is streamed and output from the car audio speaker will be described.

First, the user makes the infrared communication units of the mobile phone 21 and the car audio 121 face each other in order to enable infrared communication between the mobile phone 21 and the car audio 121. In this state, when the user selects the transmission start button (not shown) of the mobile phone, the program shown in FIG. 4 is activated, and the CPU 23 of the mobile phone 21 transmits a session connection request from the infrared communication board 35 ((not shown). Step S1). At that time, as the decryption key, the public key corresponding to the encryption key stored in the memory 27 is transmitted.

When the power of the CPU 123 of the car audio 121 is turned on, the program shown in FIG. 4 is activated, and the infrared communication board 135 determines whether to receive the session connection request (step S11). When there is a session connection request, the public key sent together with this request is stored in the memory 127 as a decryption key (step S13), and a reply is sent from the infrared communication board 135 (step S15).

The CPU 23 of the mobile phone 21 determines whether or not to receive the reply (step S3), and when the reply is received, encrypts the data to be transmitted and performs streaming transmission from the wireless LAN communication board 33 (step S5). .. Specifically, the CPU 23 gives the encryption processing unit 31 the data to be transmitted stored in the memory 27. The encryption processing unit 31 encrypts the data to be transmitted by using the encryption key stored in the memory 27. The encrypted data to be transmitted is streamed from the wireless LAN communication board 33.

Since the CPU 123 of the car audio 121 determines whether to receive the data on the wireless LAN communication board 133 (step S17), when the data is received, it is decoded and reproduced (step S19). Specifically, the CPU 123 gives the received data to the decoding processing unit 131. The decoding processing unit 131 performs decoding processing using the decoding key stored in the memory 127. The decoded data is given to the audio unit 126 and output from the speaker 128.

The CPU 23 of the mobile phone 21 determines whether or not the data to be transmitted has been sent to the end (step S7), and if it determines that the data has been transmitted, requests disconnection from the wireless LAN communication board 33 (step S9). The CPU 123 of the car audio 121 determines whether to receive the disconnection request on the wireless LAN communication board 133 (step S21), and disconnects when the disconnection request is received, and ends.

In the present embodiment, encrypted data is transmitted to the wireless LAN communication path, and the decryption key for decrypting the encrypted data is exchanged via the infrared communication path. Therefore, highly confidential transmission is possible.

In this way, even if there are multiple destination devices and it is difficult to send to only the specified terminal (in the case of wireless LAN communication), the distance and transmission direction are separately set. By providing the restricted sub-transmission path, the user can transmit the encrypted transmission target data and decrypt it on the receiving side only by bringing the two close to each other and starting the program. Therefore, the data can be easily and surely transmitted so as to be reproduced at the specified destination.

Since infrared communication is limited in distance and transmission direction as described above, it is considered that highly confidential data transmission is possible if the data to be transmitted is also transmitted via the infrared communication path. However, the infrared communication path cannot communicate unless the communication units face each other, and the transmissible distance is short. That is, data communication cannot be performed unless the terminals are continuously held in a state where communication is secured. On the other hand, in the above embodiment, once the decoding key is transmitted, data transmission becomes possible by a wireless LAN communication path without such restrictions. In particular, there is a great merit when the transmission format is such that communication is performed during playback. This makes it possible to maintain confidentiality in a simple manner.

4. Other Embodiments In the above embodiment, the case where the main transmission line and the sub-transmission line are directly provided between the first computer and the second computer has been described. However, the present invention is not limited to this, and data transmission with confidentiality may be enabled via a third computer as shown in FIG. In FIG. 5, the server 81 is the first computer, the personal computer 82 is the second computer, and the mobile phone 83 is the third terminal. The mobile phone 83 has a built-in chargeable IC card. The mobile phone 83 and the personal computer 82 are capable of infrared communication. The user first performs personal authentication with the server 81 using the mobile phone 83. Personal authentication information is sent to the personal computer 82 by infrared communication. The personal computer 82 uses the personal authentication information to perform encrypted data communication with the server 81.

Further, in FIG. 5, the case of performing one-to-one communication has been described, but as shown in FIG. 6, when the broadcast from the broadcasting station 86 is received by the televisions 87a and 87b, the mobile phone 88 The same can be applied to the case of one-to-many broadcasting, which enables reception only with a personally authenticated TV.

Further, as shown in FIG. 7, when chatting between the personal computer 92a and the personal computer 92b, the personal authentication may be performed by the mobile phones 93a and 93b, respectively. In this case, it is bidirectional.

Further, in the above embodiment, the decryption key for decryption is transmitted from the mobile phone 21, but the encryption key is sent from the car audio 121 that has received the request and is encrypted by the mobile phone 21. The conversion process may be performed.

In the above embodiment, the case where the data to be transmitted is determined has been described, but when there are a plurality of the data to be transmitted, the process of FIG. 4 may be started by selecting one of them. As a result, the user can transmit data while ensuring confidentiality by simply selecting the data to be transmitted.

In the above embodiment, the target data for confidentiality transmission is transmitted between specific devices by using an infrared communication path having a limited transmissible distance and a limited transmission direction as an auxiliary communication path. .. However, it may be a communication path having a limited transmission distance or a communication path having a limited transmission directionality. For example, wireless communication may be used in which data cannot be transmitted unless the distance is close to several centimeters even if there is no directionality. In addition to radio waves, sound waves may be used. Moreover, not only wireless but also wired may be used. Even in this case, once the confidentiality assurance information of the main transmission line is transmitted, the line connection is disconnected and the data can be transmitted by the main transmission line.

Further, since the information sent on the sub transmission / reception path is information for releasing confidentiality, the amount of data is smaller than that of the data to be transmitted. Therefore, a simple protocol or a data transfer rate that is lower than that of the main transmission / reception path may be used. Therefore, the cost of providing the sub-transmission line does not increase so much.

In the above embodiment, the case where the data to be transmitted is streamed has been described, but the data may be sent as a file and decompressed and reproduced on the receiving side. Further, when the file is transmitted, it may exist unless it is deleted by the receiving side. Therefore, after a predetermined time has passed, it may be unplayable or automatically deleted.

In the above embodiment, the case where the data to be transmitted is music data has been described, but image data (video, still image), program, and data used for the program (character data, its costume data, weapon data, etc.) are also described. It can be applied in the same way.

In the present embodiment, the case where the decryption key is adopted as the confidentiality release information has been described, but as the confidentiality release information, the connection to the network is prohibited in addition to the encryption that makes the contents unreadable. May be good. For example, hiding ESS-ID, limiting MAC address, etc. In particular, in the latter case, the same effect can be achieved by registering the ID of the transmitting device on the receiving side (car audio side in this example) and setting the standard so that reception cannot be performed from unregistered devices. Can be obtained.

Further, in the above embodiment, the case where the main transmission / reception path is wireless has been described, but the same can be applied to the case of a communication standard (for example, http) in which the confidentiality of data is not guaranteed. In this case, encryption processing may be performed to ensure confidentiality.

Further, in the above embodiment, a case where a mobile phone is used on the transmitting side and a car audio is used on the receiving side to transmit data has been described, but the transmitting side uses a portable playback device (MP3 player) as a simple data playback device. Etc.), and on the receiving side, it can also be used for audio equipment, personal computers, television receivers, and the like.

Further, as an example of bidirectionality, it can be adopted for a portable game machine, a wireless LAN terminal, and the like.

In the above embodiment, the case where the encryption key and the decryption key are stored in advance has been described, but these may be dynamically generated, and the key itself is not transmitted and the indirect information for specifying the key is specified. (Key specific information that specifies which of a plurality of keys to use, such as information for generating a key) may be exchanged. That is, either of the conventional encryption / decryption may be adopted.

In the above embodiment, encryption and decryption are provided separately, but the CPUs 23 and 123 may be executed by using a program that performs encryption and decryption.

The present invention can also be grasped as a system or terminal having the following configuration. A data transmission / reception system including a first terminal for transmitting transmission target data and a second terminal for receiving transmission target data transmitted from the first terminal, wherein the first terminal and the second terminal are provided. A means for securing a main transmission line for transmitting the data to be transmitted, a transmission distance between the first terminal and the second terminal, which is more limited than that of the main transmission line. Alternatively, a means for securing an auxiliary transmission line having a limited transmission direction, ensuring confidentiality transmitted on the main transmission line, and providing confidentiality release information for receiving the transmission target data at the second terminal. Data transmission / reception provided with a confidentiality release information determining means for determining between the first terminal and the second terminal using the sub-transmission line before transmission of data to be transmitted. system.

A first terminal that transmits data to be transmitted to a second terminal, a means for securing a main transmission line for transmitting the data to be transmitted to and from the second terminal, and the second terminal. A means for securing a sub-transmission line having a more limited transmissible distance or a limited transmission direction than the main transmission line, and ensuring confidentiality transmission target data transmitted on the main transmission line. A second device provided with a determination means for determining confidentiality release information for reception at the second terminal with the second terminal using the sub-transmission line before transmission of the transmission target data. 1 terminal.

A second terminal that receives transmission target data transmitted from the first terminal, and is a means for securing a main transmission line for transmitting the transmission target data with the first terminal, the first. A means for securing a sub-transmission line having a more limited transmissible distance or a limited transmission direction than the main transmission line, and confidentiality-ensuring transmission target data transmitted on the main transmission line. A second terminal provided with a determination means for determining confidentiality release information for receiving the data with and from the first terminal using the sub-transmission line before transmission of the transmission target data.

Further, when the sub-transmission line is a sub-transmission line having a transmission direction limited to that of the main transmission line and the transfer speed is lower than that of the main transmission line, the minimum characteristics required. In the sub-transmission line with, transmission by the main transmission line with ensured confidentiality becomes possible. Further, when the sub-transmission line is a transmission line having a transmission range smaller than that of the main transmission line and the transfer speed is lower than that of the main transmission line, it has the minimum required characteristics. Transmission on the main transmission line, which ensures confidentiality, is possible on the sub transmission line.

Further, the securing of the main transmission line and the sub transmission line includes a case where the main transmission line and the sub transmission line are secured by performing passive processing on the other side based on active processing from one of the terminals. The same applies to the determination of confidentiality release information. For example, in the above embodiment, the decryption key stored in advance in the first terminal is transmitted to the second terminal, but in response to an inquiry from the first terminal, the second terminal is sent. The encryption key corresponding to the decryption key stored in advance may be transmitted to the first terminal. As described above, the confidentiality release information for receiving the confidentiality assurance transmission target data is not limited as long as it can be determined between the first terminal and the second terminal.

In the above embodiment, in order to realize the function shown in FIG. 1, a CPU is used and this is realized by software. However, a part or all of them may be realized by hardware such as a logic circuit.

The operating system (OS) may be used to perform some processing of the above program.

<figref num="1">It is a functional block diagram of the data transmission / reception system 1 which concerns on this invention.</figref><figref num="2">FIG. 5 is a diagram showing an example of a hardware configuration in which the first device of the data transmission / reception system 1 shown in FIG. 1 is realized by using a CPU.</figref><figref num="3">It is a figure which shows an example of the hardware configuration which realized the 2nd device of the data transmission / reception system 1 shown in FIG. 1 by using a CPU.</figref><figref num="4">It is a flowchart.</figref><figref num="5">It is a figure which shows the outline of the embodiment which transmits the declassification information through the third computer.</figref><figref num="6">It is a figure which shows the outline of the embodiment which broadcasts from the 1st computer to the 2nd computer.</figref><figref num="7">It is a figure which shows the outline of the Embodiment in the case of having a chat via a server.</figref>

Code description

1 ... Data transmission / reception system 21 ... Mobile phone 23 ... CPU 27 ... Memory 31 ... Encryption processing unit 33 ... Wireless LAN communication board 35 ... Infrared communication board 121 ... Car Audio 123 CPU127 Memory 131 Decryption processing unit 133 Wireless LAN communication board 135 Infrared communication board