COMMUNICATION SYSTEM, COMPUTER PROGRAM FOR TERMINAL DEVICE, FIRST COMMUNICATION DEVICE, AND SECOND COMMUNICATION DEVICE

Abstract

To provide a technique to easily achieve encryption of connection information in intermediation of the connection information.SOLUTION: A first communication device transmits information indicating a first key to the outside. A second communication device transmits information indicating a second key to the outside. A terminal device receives the information indicating the first key from the first communication device, receives the information indicating the second key from the second communication device, receives first encrypted connection information from the first communication device, decrypts the first encrypted connection information by using the first key, encrypts the acquired connection information by using the second key, and transmits the second encrypted connection information to the second communication device. The second communication device receives the second encrypted connection information from the terminal device, and decrypts the second encrypted connection information by using second key information to acquire the connection information.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] SUMMARY Techniques are disclosed herein for communicating connection information. [Background technology]

[0002] Patent Document 1 discloses a smart device that mediates settings for wireless communication between a first device and a second device. The smart device performs NFC (abbreviation of Near Field Communication) communication with the first device and receives network information from the first device. The smart device performs NFC communication with a second device and transmits the network information to the second device. The second device connects to a wireless LAN (abbreviation of Local Area Network). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-112432 A Summary of the Invention [Problem to be solved by the invention]

[0004] This specification provides a technique for easily encrypting connection information when intermediating the connection information. [Means for solving the problem]

[0005] A communication system disclosed in this specification includes a terminal device, a first communication device that stores first key information for encrypting and decrypting information, and a second communication device that stores second key information for encrypting and decrypting information, wherein the first communication device includes a first device-side transmitting unit that transmits information indicating a first key of the first key information to an external device, and the second communication device includes a second device-side transmitting unit that transmits information indicating a second key of the second key information to an external device, and the terminal device includes a first terminal-side receiving unit that receives the information indicating the first key from the first communication device, a second terminal-side receiving unit that receives the information indicating the second key from the second communication device, and a third terminal-side receiving unit that transmits a request to the first communication device and receives first encrypted connection information from the first communication device as a response to the request, wherein the first encrypted connection information is connection information encrypted by the first communication device using the first key information, and the connection information is information regarding wireless communication with a specific device. the third terminal side receiving unit, which is information for establishing a connection; a terminal side acquisition unit, which, when the first encrypted connection information is received from the first communication device, decrypts the first encrypted connection information using the first key indicated by the information received from the first communication device and acquires the connection information; a generation unit, which encrypts the acquired connection information using the second key indicated by the information received from the second communication device and generates second encrypted connection information; and a terminal side transmitting unit, which transmits the second encrypted connection information to the second communication device; the second communication device, which comprises a device side receiving unit, which receives the second encrypted connection information from the terminal device; a device side acquisition unit, which, when the second encrypted connection information is received from the terminal device, decrypts the second encrypted connection information using the second key information and acquires the connection information; and an establishment unit, which establishes a wireless connection with the specific device using the acquired connection information.

[0006] For example, a comparative example is assumed in which the same key information is stored in both the first communication device and the second communication device, and the terminal device uses the key information to decrypt and encrypt the connection information, and mediates the transmission of the connection information from the first communication device to the second communication device. In this comparative example, for example, the first communication device and the second communication device need to share key information. In contrast, according to the above configuration, the terminal device uses a first key indicated by the information received from the first communication device to decrypt the connection information, and uses a second key indicated by the information received from the second communication device to encrypt the connection information. That is, not only when the first key and the second key are the same, but also when the first key and the second key are different, the terminal device can mediate the transmission of the connection information from the first communication device to the second communication device. There is no need to share key information between the first communication device and the second communication device. In mediating the connection information, the encryption of the connection information can be easily realized.

[0007] This specification also discloses a computer program for a terminal device, which includes a computer of the terminal device, the computer program including the following units: a first receiving unit for receiving information indicating a first key from a first communication device, when a first communication device storing first key information for encrypting and decrypting information transmits information indicating a first key of the first key information to an external device; a second receiving unit for receiving information indicating a second key from a second communication device, when a second communication device storing second key information for encrypting and decrypting information transmits information indicating a second key of the second key information to an external device; and a third receiving unit for transmitting a request to the first communication device and receiving first encrypted connection information from the first communication device as a response to the request, the first encrypted connection information being connection information encrypted by the first communication device using the first key information, and the connection information being information indicating a first key from the first communication device. the third receiving unit, which is information for establishing a wireless connection with a specific device; an acquiring unit, when the first encrypted connection information is received from the first communication device, decrypting the first encrypted connection information using the first key indicated by the information received from the first communication device and acquiring the connection information; a generating unit, which encrypts the acquired connection information using the second key indicated by the information received from the second communication device and generates second encrypted connection information; and a transmitting unit, which transmits the second encrypted connection information to the second communication device, wherein the second communication device decrypts the second encrypted connection information received from the terminal device using the second key information, acquires the connection information, and establishes a wireless connection with the specific device using the acquired connection information.

[0008] Even in this configuration, there is no need for the first communication device and the second communication device to share key information, and encryption of the connection information can be easily achieved in mediating the connection information.

[0009] This specification also discloses a second communication device, the second communication device comprising: a memory for storing second key information for encrypting and decrypting information, the second key information being different from first key information stored in a first communication device different from the second communication device; and a transmission unit for transmitting information indicating a second key of the second key information to an external device, the information indicating the second key being received by a terminal device, the terminal device receiving information indicating a first key of the first key information from the first communication device, transmitting a request to the first communication device, receiving first encrypted connection information from the first communication device as a response to the request, and transmitting the first key indicated by the information received from the first communication device to the first communication device. the transmitting unit decrypts the encrypted connection information to obtain connection information for establishing a wireless connection with the specific device, encrypts the obtained connection information using the second key indicated by the information received from the second communication device to generate second encrypted connection information, and transmits the second encrypted connection information to the second communication device; a receiving unit receives the second encrypted connection information from the terminal device; an acquiring unit, when the second encrypted connection information is received from the terminal device, decrypts the second encrypted connection information using the second key information and obtains the connection information; and an establishing unit, which establishes a wireless connection with the specific device using the acquired connection information.

[0010] This specification also discloses a first communication device, which includes a memory that stores first key information for encrypting and decrypting information, the first key information being different from second key information stored in a second communication device different from the first communication device, a first transmission unit that transmits information indicating a first key of the first key information to an external device, the information indicating the first key being received by a terminal device, and a second transmission unit that receives a request from the terminal device and transmits first encrypted connection information to the terminal device as a response to the request, the first encrypted connection information being connection information encrypted by the first communication device using the first key information, the connection information being information for establishing a wireless connection with a specific device, and the terminal device. The terminal device comprises a second transmitting unit that receives information indicating a second key of the second key information from the second communication device, decrypts the first encrypted connection information received from the first communication device using the first key indicated by the information received from the first communication device to obtain the connection information, encrypts the obtained connection information using the second key indicated by the information received from the second communication device to generate second encrypted connection information, and transmits the second encrypted connection information to the second communication device, and the second communication device decrypts the second encrypted connection information using the second key information to obtain the connection information, and establishes a wireless connection with the specific device using the obtained connection information.

[0011] In the above-mentioned second communication device and first communication device, the first communication device and the second communication device do not need to share key information, and the first communication device and the second communication device can mediate the transmission of connection information from the first communication device to the second communication device by using different key information for the first communication device and the second communication device. In mediating the connection information, encryption of the connection information can be easily realized.

[0012] The terminal device itself, a control method for implementing the terminal device, and a computer-readable recording medium storing a computer program are also novel and useful. A control method for implementing the first or second communication device, a computer program, and a computer-readable recording medium storing the computer program are also novel and useful. [Brief description of the drawings]

[0013] [Figure 1] 1 shows the configuration of a communication system. [Diagram 2] FIG. 2 shows a sequence diagram of a process implemented by the communication system of the first embodiment. [Diagram 3] A continuation of Figure 2 is shown. [Figure 4] FIG. 11 is a sequence diagram of a process implemented by a communication system according to a second embodiment. [Diagram 5] A continuation of Figure 4 is shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] (First embodiment) (Configuration of communication system 2; Figure 1) As shown in FIG. 1, the communication system 2 includes a terminal device 10, two printers 100 and 200, and an access point 500 (hereinafter, the access point is referred to as "AP"). The terminal device 10 is a mobile terminal such as a tablet PC or a smartphone. In a modified example, the terminal device 10 may be a terminal device such as a desktop PC or a notebook PC. The printer 100 is currently connected to a LAN (abbreviation of Local Area Network) 4. In a modified example, the printer 100 does not need to be currently connected to the LAN 4.

[0015] LAN4 is a wireless LAN formed by AP 500. AP 500 stores an SSID (short for Service Set Identifier) ​​"ap01" that identifies LAN4, and a password "xxxx" that is used in LAN4.

[0016] For example, a user purchases a new printer 200. In this embodiment, a situation is assumed in which the printer 200 is newly connected to the LAN 4.

[0017] (Configuration of Printer 100) The printer 100 includes a display unit 112, an operation unit 114, a wireless LAN interface 120, a Bluetooth (registered trademark) interface 122, and a control unit 130. Each unit 112 to 130 is connected to a bus line (reference numbers omitted). In the following, the interface is referred to as "I / F." Moreover, Bluetooth is referred to as "BT."

[0018] The display unit 112 is a display for displaying various information. The operation unit 114 has a plurality of keys. A user can input various instructions to the printer 100 by operating the operation unit 114. The display unit 112 may function as a touch panel (i.e., an operation unit) that accepts instructions from a user.

[0019] The wireless LAN I / F 120 is an I / F for performing wireless communication via the LAN 4. The wireless communication via the LAN 4 is, for example, communication according to the Wi-Fi method (hereinafter, referred to as "Wi-Fi communication"). The Wi-Fi method is, for example, a wireless communication method for performing wireless communication according to the IEEE (abbreviation of The Institute of Electrical and Electronics Engineers, Inc.) 802.11 standard and standards equivalent thereto (for example, 802.11a, 11b, 11g, 11n, 11ac, etc.).

[0020] The BTI / F 122 is an I / F for executing wireless communication according to the BT method (hereinafter referred to as "BT communication"). The BT method is a wireless communication method based on the IEEE802.15.1 standard and standards equivalent thereto, for example. More specifically, the BTI / F 122 supports BLE (short for Bluetooth Low Energy). BLE is a standard realized in BT method version 4.0 and later versions. The BTI / F 122 can execute wireless communication according to BLE (hereinafter referred to as "BLE communication").

[0021] The differences between the Wi-Fi system and the BT system will be described. The communication speed of Wi-Fi communication (for example, the maximum communication speed is 600 Mbps) is faster than the communication speed of BT communication (for example, the maximum communication speed is 24 Mbps). The carrier frequency in Wi-Fi communication is the 2.4 GHz band or the 5.0 GHz band. The carrier frequency in BT communication is the 2.4 GHz band. That is, when the 5.0 GHz band is adopted as the carrier frequency in Wi-Fi communication, the carrier frequency in Wi-Fi communication is different from the carrier frequency in BT communication. In addition, the maximum distance at which Wi-Fi communication can be performed (for example, about 100 m) is greater than the maximum distance at which BT communication can be performed (for example, about several tens of meters).

[0022] The control unit 130 includes a CPU 132 and a memory 134. The CPU 132 executes various processes in accordance with a program 140 stored in the memory 134. The memory 134 is configured by a volatile memory, a non-volatile memory, and the like.

[0023] The memory 134 further stores AP information AI for connecting to the LAN 4. The AP information AI is information about the AP 500, and includes the SSID "ap01" and the password "xxxx".

[0024] The memory 134 further stores key information KI1. The key information KI1 includes a pair of keys according to a public key cryptosystem, that is, a public key PU1 and a private key PR1. The key information KI1 further includes a key ID "k01" for identifying the public key PU1.

[0025] Printer 100 is assigned the printer name "printer1" that identifies printer 100. Printer 200 is assigned the printer name "printer2" that identifies printer 200. Printer 200 has the same configuration as printer 100, and includes a display unit 212, an operation unit 214, a wireless LAN I / F 220, a BTI / F 222, and a control unit 230. A memory (not shown) in control unit 230 stores key information KI2. Key information KI1 includes a public key PU2, a private key PR2, and a key ID "k02" for identifying public key PU2.

[0026] (Configuration of terminal device 10) The terminal device 10 includes a display unit 12, an operation unit 14, a wireless LAN I / F 20, a BTI / F 22, and a control unit 30. Each unit 12 to 30 is connected to a bus line (reference numerals omitted).

[0027] The display unit 12 is a display for displaying various information, and the operation unit 14 is, for example, a touch panel. The operation unit 14 is capable of receiving various instructions.

[0028] The control unit 30 includes a CPU 32 and a memory 34. The CPU 32 executes various processes in accordance with programs 40, 42 stored in the memory 34. The memory 34 is composed of a volatile memory, a non-volatile memory, etc. The OS (short for Operating System) program 40 is a program for executing basic processes of the terminal device 10. The application program 42 (hereinafter, referred to as "app 42") is a program for connecting the printer to the LAN 4.

[0029] The memory 34 further stores AP information AI. The terminal device 10 can connect to the LAN 4 using the AP information AI.

[0030] The memory 34 further stores a key table 44 that stores a plurality of public keys. The key table 44 stores, for each of a plurality of public keys, a key ID (e.g., "k01") that identifies the public key and the public key (e.g., PU1) in association with each other. The above-mentioned application 42 and key table 44 are downloaded to the terminal device 10 from a server (not shown) on the Internet, for example. The application 42 and key table 44 are uploaded to the server by, for example, a vendor of a printer (e.g., 100).

[0031] (Processing implemented by communication system 2; Fig. 2, Fig. 3) The processing realized by the communication system 2 will be described with reference to Figs. 2 and 3. In the initial stage of this case, the terminal device 10 is currently connected to the LAN 4. In addition, in a modified example, the terminal device 10 may not currently be connected to the LAN 4. In addition, in the following, for ease of understanding, the processing executed by each CPU of each device (e.g., the CPU 32 of the terminal device 10, etc.) will be described with each device (e.g., the terminal device 10, etc.) as the subject, rather than each CPU as the subject.

[0032] At T10, the printer 100 transmits an Advertise signal conforming to the BLE method to the outside via the BTI / F 122. The Advertise signal is a so-called beacon signal, and is a signal with no designated destination. In other words, the printer 100 transmits the Advertise signal to an unspecified number of devices. The Advertise signal of the printer 100 includes the key ID "k01" of the printer 100 and the printer name "printer1". The printer 100 starts transmitting the Advertise signal when the power is turned on as a trigger. Note that the dashed arrow in FIG. 2 indicates BLE communication. The same applies to FIGS. 3 to 5 described later.

[0033] In this case, the user opens the packaging of the printer 200 and performs an operation to power on the printer 200. As a result, the printer 200 starts transmitting an Advertise signal to the outside at T12. The Advertise signal of the printer 200 includes the key ID "k02" of the printer 200 and the printer name "printer2".

[0034] When the printers 100 and 200 transmit an Advertise signal to the outside, the terminal device 10 receives the Advertise signal from the printers 100 and 200 via the BTI / F 22 at T10 and T12.

[0035] In T20, the terminal device 10 displays a terminal confirmation screen on the display unit 12 for confirming that the AP information currently stored in the printer (e.g., 100) is to be transferred to another printer (e.g., 200). The terminal confirmation screen includes a message MS, an "OK" button, and a "Cancel" button. The message MS includes the printer name "printer1" included in the Advertise signal of T10 as the source of the AP information, and the printer name "printer2" included in the Advertise signal of T12 as the destination of the AP information. For example, if both the terminal device 10 and the printer 100 are currently connected to the LAN4, the terminal device 10 searches for printers in the LAN4 and determines the printer name "printer1" that matches the search result as the source of the AP information. Then, the terminal device 10 determines the printer name "printer2" that does not match the search result as the destination of the AP information. The display of the terminal confirmation screen allows the user to confirm the source and destination printers.

[0036] In a modified example, the terminal confirmation screen may include an input field for specifying the source from the printer name "printer1" in the Advertise signal of T10 and the printer name "printer2" in the Advertise signal of T12, and an input field for specifying the destination from the two printer names. In other words, the source and destination may be specified by the user.

[0037] In T22, the user selects the "OK" button in the terminal confirmation screen. When the terminal device 10 accepts the selection of the "OK" button in T22, in T24, the terminal device 10 executes predetermined communication (Scan Request, Scan Response, etc.) according to the BT method between the terminal device 10 and the printer 100 via the BTI / F 22 to establish a BT connection with the printer 100. The BT connection is a wireless connection according to the BLE method, and is a wireless connection according to the so-called L2CAP (abbreviation of Logical Link Control and Application Protocol).

[0038] At T26, the terminal device 10 transmits an AP information request to the printer 100, requesting the AP information AI stored in the printer 100, via the BTI / F 22, using the BT connection.

[0039] When the printer 100 receives an AP information request from the terminal device 10 using the BT connection via the BTI / F 122 in T26, in T30, it displays a printer confirmation screen on the display unit 112. The printer confirmation screen includes a message confirming that the transfer of the AP information AI to another printer is permitted, an "OK" button, and a "Cancel" button.

[0040] In T32, the user operates operation unit 114 to select the "OK" button on the printer confirmation screen. When printer 100 accepts the selection of the "OK" button in T32, printer 100 encrypts the AP information AI using private key PR1 of key information KI1 in T34. This generates encrypted AP information to be transmitted to terminal device 10. Note that in a modified example, printer 100 may encrypt the AP information AI in advance before accepting the selection of the "OK" button.

[0041] In T36, the printer 100 uses a BT connection via the BTI / F 122 to transmit the encrypted AP information to the terminal device 10 as a response to the AP information request in T26. If the "Cancel" button on the printer confirmation screen is selected, the printer 100 skips the processes from T34 onwards and ends the process in FIG. 2.

[0042] For example, a comparative example is assumed in which the printer confirmation screen is not displayed and the encrypted AP information is sent to the terminal device 10 without receiving an instruction from the user. In this comparative example, even if the user of the terminal device 10 is not near the printer 100, the encrypted AP information may be sent to the terminal device 10. In this case, for example, the encrypted AP information may be sent to the terminal device 10 by a third party who is far from the printer 100. In contrast, according to the configuration of this embodiment, the encrypted AP information can be sent to the terminal device 10 in response to an instruction from a user who is near the printer 100, for example, an administrator of the printer 100. It is possible to prevent a third party from acquiring the encrypted AP information. Note that the configuration of the comparative example described above may be adopted in the modified example.

[0043] In T36, the terminal device 10 receives the encrypted AP information from the printer 100 as a response to the AP information request in T26, via the BTI / F 22 and using the BT connection.

[0044] At T40, the terminal device 10 obtains from the key table 44 the public key PU1 associated with the key ID "k01" received from the printer 100 at T10, and the public key PU2 associated with the key ID "k02" received from the printer 200 at T12.

[0045] For example, a comparative example is assumed in which an Advertise signal including public keys PU1 and PU2 is received from printers 100 and 200 at T10 and T12. In this comparative example, the Advertise signal, which is a beacon signal, is received by a terminal device of a third party, and the public keys PU1 and PU2 can be acquired by the third party. In contrast, according to the configuration of this embodiment, the Advertise signal includes a key ID, and the public key is acquired from the key table 44 in the terminal device 10 using the key ID. In other words, the third party can only acquire the key ID. It is possible to prevent the third party from acquiring the public key. Note that the configuration of the comparative example described above may be adopted in the modified example.

[0046] In T42, the terminal apparatus 10 uses the public key PU1 (i.e., the public key of the printer 100) acquired in T40 to decrypt the encrypted AP information received in T36. As a result, the terminal apparatus 10 acquires the AP information AI.

[0047] In T44, the terminal device 10 encrypts the AP information AI acquired in T42 using the public key PU2 acquired in T40 (i.e., the public key of the printer 200). As a result, the encrypted AP information to be transmitted to the printer 200 is generated.

[0048] 3 is the same as T24 in Fig. 2, except that the BT connection with the printer 100 is disconnected and the BT connection with the printer 200 is established. Note that the solid arrows in Fig. 3 indicate Wi-Fi communication. The same applies to Figs. 4 and 5 described below.

[0049] In T52, the terminal device 10 uses a BT connection via the BTI / F 22 to transmit the encrypted AP information generated in T44 of Fig. 2 and message information indicating a message to be displayed on a connection confirmation screen described later (for example, plain text of the SSID "ap01" indicating the AP 500, the message information is omitted from the drawing) to the printer 200. Note that in a modified example, the transmission of the message information can be omitted.

[0050] At T52, the printer 200 receives the encrypted AP information from the terminal device 10 via the BTI / F 222 using the BT connection.

[0051] In T60, the printer 200 displays a connection confirmation screen on the display unit 212. The connection confirmation screen includes a message for confirming the connection to the AP (for example, 500), an "OK" button, and a "Cancel" button.

[0052] In T62, the user operates operation unit 214 to select the "OK" button in the connection confirmation screen. When printer 200 accepts the selection of the "OK" button in T62, printer 200 uses private key PR2 of key information KI2 to decrypt the encrypted AP information received in T52 in T64. As a result, printer 200 acquires AP information AI. Note that if the "Cancel" button in the connection confirmation screen is selected, printer 200 skips the processes from T64 onwards and ends the process in FIG. 3.

[0053] For example, as shown in T59 of FIG. 3, a comparative example is assumed in which the encrypted AP information is decrypted before the "OK" button in the connection confirmation screen is selected. In this comparative example, even if the "Cancel" button in the connection confirmation screen is selected, the process of decrypting the encrypted AP information is unnecessarily executed. In contrast, according to the configuration of this embodiment, as shown in T64, the encrypted AP information is decrypted after the "OK" button in the connection confirmation screen is selected. It is possible to prevent the encrypted AP information from being unnecessarily decrypted. By not decrypting the encrypted AP information, it is possible to reduce the processing load of the printer 200 when the "Cancel" button in the connection confirmation screen is selected. Note that the configuration of the comparative example described above may be adopted in the modified example.

[0054] In T70, the printer 200 executes 4way-handshake communication with the AP 500. In at least a part of the 4way-handshake communication, the printer 200 and the AP 500 communicate encrypted information encrypted with the password "xxxx" included in the AP information AI acquired in T62. If the encrypted information is successfully decrypted, a wireless connection based on the Wi-Fi system is established between the printer 200 and the AP 500. As a result, the printer 200 is connected to the LAN 4 formed by the AP 500. In a modified example, SAE (short for Simultaneous Authentication of Equals, commonly known as "Dragonfly") communication may be used instead of the 4way-handshake communication.

[0055] For example, a comparative example is assumed in which a connection confirmation screen is not displayed and a wireless connection with the AP500 is established without receiving an instruction from a user. In this comparative example, even if the user of the printer 200 is not near the printer 200, a wireless connection with the AP500 may be established. In this case, for example, a wireless connection with the AP500 may be established without the knowledge of the administrator of the printer 200. In contrast, according to the configuration of this embodiment, a wireless connection with the AP500 can be established in response to an instruction from a user near the printer 200, for example, an administrator of the printer 200. It is possible to prevent a wireless connection with the AP500 from being established without the knowledge of the administrator of the printer 200. Note that the configuration of the comparative example described above may be adopted in the modified example.

[0056] In the next T72, the printer 200 transmits the IP address of the printer 200 in the LAN 4 to the terminal device 10 by using the BT connection via the BTI / F 222. For example, the IP address is assigned to the printer 200 by the AP 500.

[0057] At T72, when the terminal device 10 receives the IP address of the printer 200 from the printer 200 via the BTI / F 22 using the BT connection, the terminal device 10 stores the IP address in the memory .

[0058] In the next step T80, when the terminal device 10 receives a print instruction on the operation unit 14, in T82, it transmits print data corresponding to the image to be printed via the wireless LAN I / F 20, LAN 4, and AP 500 to the printer 200 indicated by the IP address received in T72.

[0059] In T80, the printer 200 receives print data from the terminal device 10 via the wireless LAN I / F 220, the LAN 4, and the AP 500, and in T84, executes printing of an image corresponding to the print data.

[0060] (Effects of this embodiment) For example, a comparative example is assumed in which the same key information KI1 is stored in both the printer 100 and the printer 200, and the terminal device 10 uses the key information KI1 to execute decryption and encryption of the AP information AI, and mediates the transmission of the AP information AI from the printer 100 to the printer 200. In this comparative example, for example, the printer 100 and the printer 200 need to share the key information KI1. In contrast, according to the above configuration, the terminal device 10 uses the public key PU1 acquired by the key ID "k01" received from the printer 100 to decrypt the encrypted AP information (T42 in FIG. 2), and uses the public key PU2 acquired by the key ID "k02" received from the printer 200 to encrypt the AP information AI (T44 in FIG. 2). That is, not only when the public key PU1 and the public key PU2 are the same, but also when the public key PU1 and the public key PU2 are different, the terminal device 10 can mediate the transmission of the AP information AI from the printer 100 to the printer 200 (the AP information AI can be transferred). There is no need to share key information between the printer 100 and the printer 200. In mediating the AP information AI, encryption of the AP information AI can be easily realized.

[0061] For example, a comparative example is assumed in which the printer 100 stores a first common key according to a common key cryptosystem, and the printer 200 stores a second common key. In this comparative example, the terminal device 10 receives information (e.g., an ID) indicating the first common key from the printer 100, and receives information (e.g., an ID) indicating the second common key from the printer 200. Then, the terminal device 10 uses the first common key to decrypt the AP information encrypted by the printer 100, and uses the second common key to encrypt the AP information to be sent to the printer 200. For example, when the encrypted AP information and the second common key are acquired by a third party, the encrypted AP information is decrypted by the second common key, and the third party can acquire the AP information. In contrast, according to the configuration of this embodiment, a public key cryptosystem is used. Therefore, even if the encrypted AP information and the public key are acquired by a third party, the private key is not acquired by the third party, so that the encrypted AP information can be prevented from being decrypted. Note that the configuration of the comparative example described above may be adopted in a modified example.

[0062] Furthermore, according to the configuration of this embodiment, the Advertise signal from the printer 100 includes the printer name of the printer 100, "printer1" (T10 in FIG. 2), and the Advertise signal from the printer 200 includes the printer name of the printer 200, "printer2" (T12). This allows the terminal device 10 to know the printer 100 that is the sender of the AP information AI, and the printer 200 that is the destination of the AP information AI. The terminal device 10 can appropriately mediate the transmission of the AP information AI from the printer 100 to the printer 200.

[0063] (Correspondence) The communication system 2, the terminal device 10, the printer 100, and the printer 200 are examples of a "communication system," a "terminal device," a "first communication device," and a "second communication device," respectively. The display unit 12 of the terminal device 10 is an example of a "display unit." The operation unit 114 of the printer 100 and the printer name "printer1" are examples of a "first operation unit" and a "first device identification information," respectively. The operation unit 214 of the printer 200 and the printer name "printer2" are examples of a "second operation unit" and a "second device identification information," respectively. The key information KI1, the public key PU1, the private key PR1, and the key ID "k01" of the printer 100 are examples of a "first key information," a "first key," a "third key," and a "first key identification information," respectively. The key ID "k01" is an example of "information indicating a first key." The key information KI2, the public key PU2, the private key PR2, and the key ID "k02" of the printer 200 are examples of "second key information," "second key," "fourth key," and "second key identification information," respectively. The key ID "k02" is an example of "information indicating a second key." The AP 500 and the AP information AI are examples of "specific device" and "connection information," respectively. The terminal confirmation screen of T20 in FIG. 2 is an example of a "screen." The AP information request of T26 in FIG. 2 and the encrypted AP information of T36 are examples of "request" and "first encrypted connection information," respectively. Selecting the "OK" button in the printer confirmation screen in T32 in FIG. 2 is an example of a "first predetermined operation." Selecting the "OK" button in the connection confirmation screen in T62 in FIG. 3 is an example of a "second predetermined operation." The encrypted AP information of T52 in FIG. 3 is an example of "second encrypted connection information."

[0064] In the "communication system", T10 in FIG. 2 is an example of a process realized by the "first device side transmitting unit" and the "first terminal side receiving unit". T12 is an example of a process realized by the "second device side transmitting unit" and the "second terminal side receiving unit". T36 is an example of a process realized by the "third terminal side receiving unit". T42 is an example of a process realized by the "terminal side acquiring unit". T44 is an example of a process realized by the "generating unit". T52 in FIG. 3 is an example of a process realized by the "terminal side transmitting unit" and the "device side receiving unit". T64 and T70 are examples of a process realized by the "device side acquiring unit" and the "establishing unit", respectively.

[0065] In the "computer program for terminal device," T10, T12, T36, T42, and T44 in FIG. 2 and T52 in FIG. 3 are examples of processing realized by the "first receiving unit," "second receiving unit," "third receiving unit," "acquisition unit," "generation unit," and "transmission unit," respectively.

[0066] In the "second communication device", the memory in the control unit 230 is an example of the "memory". T12 in Fig. 2 and T52, T64, and T70 in Fig. 3 are examples of processes realized by the "transmitting unit", "receiving unit", "acquiring unit", and "establishing unit", respectively.

[0067] In the "first communication device," the memory 134 is an example of a "memory." T10 and T36 in Fig. 2 are examples of processes realized by the "first transmission unit" and the "second transmission unit," respectively.

[0068] (Second Example) In the second embodiment, the communication between the terminal device 10 and the printer 100 and the communication between the terminal device 10 and the printer 200 utilizes wireless communication conforming to the Wi-Fi standard.

[0069] In this embodiment, the wireless LAN I / Fs 20, 120, and 220 further support the WFD (short for Wi-Fi Direct (registered trademark)) method established by the Wi-Fi Alliance. The WFD method is a wireless communication method described in the standard "Wi-Fi Peer-to-Peer (P2P) Technical Specification Version 1.1" created by the Wi-Fi Alliance.

[0070] (Processing implemented by communication system 2; Fig. 4, Fig. 5) 4 and 5, a process implemented by the communication system 2 of the second embodiment will be described. In the initial stage of this case, the terminal device 10 and the printer 100 are currently connected to the LAN 4.

[0071] 2, except that the Advertise signal includes WFD information WI1 of the printer 100. The WFD information WI1 includes information (e.g., SSID) for connecting to a wireless network formed by the printer 100 operating as a Group Owner (i.e., parent station) in the WFD system. T112 is similar to T12 in FIG. 2, except that the Advertise signal includes WFD information WI2 of the printer 200.

[0072] T120 and T122 are the same as T20 and T22 in Fig. 2. As described above, the terminal device 10 and the printer 100 are currently connected to the LAN 4. In T126, the terminal device 10 transmits an AP connection request to the printer 100 via the wireless LAN I / F 20, the LAN 4, and the AP 500. Note that in this case, a BT connection is not established between the terminal device 10 and the printer 100.

[0073] T130 to T134 are the same as T30 to T34 in Fig. 2. T136 is the same as T36 in Fig. 2, except that the encrypted AP information is transmitted to the terminal device 10 via the LAN 4 and the AP 500. T140 to T144 are the same as T40 to T44 in Fig. 2.

[0074] Next, at T150 in Fig. 5, the terminal device 10 executes 4way-handshake communication with the printer 200 operating as the Group Owner. In at least a part of the process of the 4way-handshake communication, the WFD information WI2 received from the printer 200 at T112 in Fig. 4 is used. Then, a wireless connection according to the WFD method is established between the terminal device 10 and the printer 200. As a result, the terminal device 10 operates as a client (i.e., a child station) of the wireless network formed by the printer 200.

[0075] T152 is similar to T52 in Fig. 3, except that a wireless connection according to the WFD method is used. T160 to T170 are similar to T60 to T70 in Fig. 3. T172 is similar to T72 in Fig. 3, except that a wireless connection according to the WFD method is used. T180 to T184 are similar to T80 to T84 in Fig. 3.

[0076] In this embodiment, as in the first embodiment, encryption of the AP information AI can be easily realized in mediating the AP information AI. Also, as described above, the communication speed of Wi-Fi communication is faster than the communication speed of BT communication. In this embodiment, the communication speed between the terminal device 10 and each of the printers 100, 200 can be made faster than in the first embodiment. In contrast, the first embodiment has the advantage that each of the devices 10, 100, 200 does not need to support the WFD method.

[0077] (Correspondence) In the "communication system", T136 in Fig. 2 is an example of a process realized by a "third terminal-side receiving unit". T152 in Fig. 3 is an example of a process realized by a "terminal-side transmitting unit" and an "apparatus-side receiving unit".

[0078] Although specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above. Modifications of the above-mentioned embodiments are listed below.

[0079] (Variation 1) At least one of the "first communication device" and the "second communication device" may be, for example, a terminal device such as a scanner, a FAX machine, a multi-function device, or a PC.

[0080] (Variation 2) At least one of the "first key information" and the "second key information" may be information including, for example, a common key and an ID that identifies the common key. In another variation, at least one of the information may include a public key and a private key, but may not include a key ID.

[0081] (Variation 3) At least one of the "information indicating the first key information" and the "information indicating the second key information" is not limited to a key ID, and may be, for example, the public key itself. In this variation, at least one of the "first key identification information" and the "second key identification information" can be omitted.

[0082] (Variation 4) The "specific device" is not limited to the AP 500, but may be, for example, a device that operates as a Group Owner in the WFD method (for example, the terminal device 10) or a device that operates as a parent station in the SoftAP method (for example, the terminal device 10).

[0083] (Variation 5) In each of the above embodiments, the "OK" button in the printer confirmation screen is selected (T32 in FIG. 2). Alternatively, the printer confirmation screen may include an input field for authentication information (e.g., a user password). Then, the printer 100 may transmit encrypted AP information to the terminal device 10 if authentication is successful using the information input in the input field. In this variation, inputting information in the input field is an example of a "first predetermined operation." In another variation, the user may hold a card key over the printer 100. Then, the printer 100 may transmit encrypted AP information to the terminal device 10 if authentication is successful using the information in the card key. In this variation, holding the card key over the printer 100 is an example of a "first predetermined operation."

[0084] (Variation 6) The processes of T30 and T32 in Fig. 2 do not have to be executed. In this variation, the "first operation unit" and the "first predetermined operation" can be omitted.

[0085] (Variation 7) In each of the above embodiments, the "OK" button in the connection confirmation screen is selected (T62 in FIG. 3). Alternatively, the connection confirmation screen may include an input field for authentication information. Then, printer 200 may establish a wireless connection with AP 500 if authentication using the information input in the input field is successful. In this variation, inputting information in the input field is an example of a "second specified operation." In another variation, the user may hold a card key over printer 200. Then, printer 200 may establish a wireless connection with AP 500 if authentication using the information in the card key is successful. In this variation, holding the card key over printer 100 is an example of a "second specified operation."

[0086] (Modification 8) The processes of T60 and T62 in Fig. 3 do not have to be executed. In this modification, the "second operation unit" and the "second predetermined operation" can be omitted.

[0087] (Modification 9) At least one of the "information indicating the first key information" and the "information indicating the second key information" may be transmitted to an unspecified number of devices by broadcast or multicast.

[0088] (Modification 10) Each of the devices 10, 100, and 200 does not have to support version 4.0 of the Bluetooth system (i.e., the BLE system). Each of the devices 10, 100, and 200 may support a version of the Bluetooth system earlier than version 4.0.

[0089] (Modification 11) The Advertise signal does not have to include the printer name. In this modification, at least one of the "first device identification information" and the "second device identification information" can be omitted.

[0090] (Modification 12) The process of T20 in Fig. 2 does not have to be executed. In this modification, the "screen" can be omitted.

[0091] (Variation 13) In each of the above embodiments, the processes in FIGS. 2 to 5 are realized by software (e.g., programs 40, 42, 140, etc.), but at least one of these processes may be realized by hardware such as a logic circuit.

[0092] In addition, the technical elements described in this specification or drawings exert technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technologies exemplified in this specification or drawings achieve multiple objectives simultaneously, and achieving one of those objectives is itself technically useful. The features of the technology disclosed in this specification are listed below. (Item 1) 1. A communication system comprising: A terminal device; a first communication device that stores first key information for encrypting and decrypting information; a second communication device that stores second key information for encrypting and decrypting information; Equipped with The first communication device is a first device-side transmitting unit configured to transmit information indicating a first key among the first key information to an outside; The second communication device is a second device-side transmitting unit configured to transmit information indicating a second key among the second key information to an outside; The terminal device a first terminal side receiving unit that receives the information indicating the first key from the first communication device; a second terminal side receiving unit that receives the information indicating the second key from the second communication device; a third terminal side receiving unit that transmits a request to the first communication device and receives first encrypted connection information from the first communication device as a response to the request, the first encrypted connection information being connection information encrypted by the first communication device using the first key information, and the connection information being information for establishing a wireless connection with a specific device; a terminal side acquisition unit that, when the first encrypted connection information is received from the first communication device, decrypts the first encrypted connection information by using the first key indicated by the information received from the first communication device, and acquires the connection information; a generating unit that encrypts the acquired connection information by using the second key indicated by the information received from the second communication device to generate second encrypted connection information; a terminal side transmitting unit that transmits the second encrypted connection information to the second communication device; Equipped with The second communication device is a device side receiving unit for receiving the second encrypted connection information from the terminal device; a device-side acquisition unit that, when the second encrypted connection information is received from the terminal device, decrypts the second encrypted connection information by using the second key information and acquires the connection information; an establishment unit that establishes a wireless connection with the specific device by using the acquired connection information; A communication system comprising: (Item 2) the first key information includes the first key which is a public key and a third key which is a private key; the second key information includes the second key which is a public key and a fourth key which is a private key; the first communication device encrypts the connection information by using the third key of the first key information; 2. The communication system according to item 1, wherein the device side acquisition unit decrypts the second encrypted connection information by using the fourth key of the second key information. (Item 3) the information indicating the first key includes first key identification information that identifies the first key; the information indicating the second key includes second key identification information that identifies the second key; The terminal device further comprises: a first key acquisition unit that acquires the first key by using the first key identification information included in the information received from the first communication device; a second key acquisition unit that acquires the second key by using the second key identification information included in the information received from the second communication device; 3. The communication system according to item 1 or 2, comprising: (Item 4) The first communication device further comprises: A first operation unit; a third device-side transmitting unit configured to transmit the first encrypted connection information to the terminal device as the response when a first predetermined operation is performed on the first operation unit after the request is received from the terminal device, and configured not to transmit the response to the terminal device when the first predetermined operation is not performed on the first operation unit after the request is received from the terminal device; 4. A communication system according to any one of claims 1 to 3, comprising: (Item 5) The second communication device further includes a second operation unit. the establishment unit establishes a wireless connection with the specific device when a second predetermined operation is performed on the second operation unit; 5. The communication system according to any one of items 1 to 4, wherein if the second predetermined operation is not performed on the second operation unit, a wireless connection with the specific device is not established. (Item 6) the device-side acquisition unit decrypts the second encrypted connection information when the second predetermined operation is performed on the second operation unit; 6. The communication system according to item 5, wherein if the second specified operation is not performed on the second operation unit, the second encrypted connection information is not decrypted. (Item 7) 6. The communication system according to item 5, wherein the device side acquisition unit decrypts the second encrypted connection information before the second predetermined operation is performed on the second operation unit. (Item 8) The first device side transmitting unit transmits the information indicating the first key to an unspecified number of devices. Send to 8. The communication system according to any one of claims 1 to 7, wherein the second device side transmitting unit transmits the information indicating the second key to an unspecified number of devices. (Item 9) the first device-side transmitting unit transmits the information indicating the first key to an unspecified number of devices by using an Advertise signal conforming to a Bluetooth standard version 4.0 or later; 9. The communication system according to item 8, wherein the second device side transmitting unit transmits the information indicating the second key to an unspecified number of devices using the Advertise signal. (Item 10) the first device side transmitting unit further transmits first device identification information for identifying the first communication device; the second device side transmitting unit further transmits second device identification information for identifying the second communication device; the first terminal side receiving unit further receives the first device identification information from the first communication device; the second terminal side receiving unit further receives the second device identification information from the second communication device; the third terminal side receiving unit receives the first encrypted connection information from the first communication device identified by the received first device identification information; 10. The communication system according to any one of claims 1 to 9, wherein the terminal side transmitting unit transmits the second encrypted connection information to the second communication device identified by the received second device identification information. (Item 11) The terminal device further comprises: A display unit; a display control unit that causes the display unit to display a screen including an image corresponding to the first device identification information as a transmission source of the connection information and an image corresponding to the second device identification information as a transmission destination of the connection information; Item 11. The communication system according to item 10, comprising: (Item 12) 12. The communication system according to any one of claims 1 to 11, wherein the third terminal side receiving unit, the terminal side transmitting unit, and the device side receiving unit use communication according to a Bluetooth system. (Item 13) 12. The communication system according to any one of claims 1 to 11, wherein the third terminal side receiving unit, the terminal side transmitting unit, and the device side receiving unit use communication according to a Wi-Fi standard. (Item 14) A computer program for a terminal device, comprising: The terminal device computer is composed of the following parts: a first receiving unit that receives information indicating a first key from a first communication device that stores first key information for encrypting and decrypting information when the first communication device transmits information indicating a first key from the first key information to an external device; a second receiving unit that receives information indicating a second key from a second communication device that stores second key information for encrypting and decrypting information when the second communication device transmits information indicating a second key from the second key information to an external device; a third receiving unit that transmits a request to the first communication device and receives first encrypted connection information from the first communication device as a response to the request, the first encrypted connection information being connection information encrypted by the first communication device using the first key information, and the connection information being information for establishing a wireless connection with a specific device; an acquisition unit that, when the first encrypted connection information is received from the first communication device, decrypts the first encrypted connection information by using the first key indicated by the information received from the first communication device, and acquires the connection information; a generating unit that encrypts the acquired connection information by using the second key indicated by the information received from the second communication device to generate second encrypted connection information; a transmission unit that transmits the second encrypted connection information to the second communication device, the second communication device using the second key information to decrypt the second encrypted connection information received from the terminal device, acquires the connection information, and establishes a wireless connection with the specific device using the acquired connection information; A computer program that functions as a (Item 15) a second communication device, A memory that stores second key information for encrypting and decrypting information, the second key information being different from first key information stored in a first communication device that is different from the second communication device; A transmission unit that transmits information indicating a second key of the second key information to an outside, the information indicative of the second key is received by a terminal device; The terminal device receiving information indicating a first key of the first key information from the first communication device; sending a request to the first communication device and receiving first encrypted connection information from the first communication device as a response to the request; decrypting the first encrypted connection information by using the first key indicated by the information received from the first communication device, and acquiring connection information for establishing a wireless connection with a specific device; encrypting the acquired connection information using the second key indicated by the information received from the second communication device to generate second encrypted connection information; sending the second encrypted connection information to the second communication device; The transmitting unit; a receiving unit that receives the second encrypted connection information from the terminal device; an acquisition unit that, when the second encrypted connection information is received from the terminal device, decrypts the second encrypted connection information by using the second key information and acquires the connection information; an establishment unit that establishes a wireless connection with the specific device by using the acquired connection information; A second communication device comprising: (Item 16) A first communication device, A memory that stores first key information for encrypting and decrypting information, the first key information being different from second key information stored in a second communication device different from the first communication device; a first transmission unit configured to transmit information indicating a first key among the first key information to an outside, the information indicating the first key being received by a terminal device; a second transmission unit configured to receive a request from the terminal device and transmit first encrypted connection information to the terminal device as a response to the request, the first encrypted connection information is information obtained by encrypting connection information by the first communication device using the first key information, and the connection information is information for establishing a wireless connection with a specific device; The terminal device receiving information indicating a second key from the second communication device; decrypting the first encrypted connection information received from the first communication device using the first key indicated by the information received from the first communication device to obtain the connection information; encrypting the acquired connection information using the second key indicated by the information received from the second communication device to generate second encrypted connection information; Sending the second encrypted connection information to the second communication device; the second communication device uses the second key information to decrypt the second encrypted connection information, acquires the connection information, and establishes a wireless connection with the specific device using the acquired connection information; The second transmitting unit; A first communication device comprising: [Explanation of symbols]

[0093] 2: communication system, 4: LAN, 10: terminal device, 12: display unit, 14: operation unit, 20: wireless LAN I / F, 22: BTI / F, 30: control unit, 34: memory, 40: OS program, 42: application, 44: key table, 100: printer, 112: display unit, 114: operation unit, 120: wireless LAN I / F, 122: BTI / F, 130: control unit, 134: memory, 140: program, 200: printer, 212: display unit, 214: operation unit, 220: wireless LAN I / F, 222: BTI / F, 230: control unit, 500: AP, AI: AP information, KI1, KI2: key information, MS: message, PU1, PU2: public key, PR1, PR2: private key, WI1, WI2: WFD information

Claims

1. 1. A communication system comprising: A terminal device; a first communication device that stores first key information for encrypting and decrypting information; a second communication device that stores second key information for encrypting and decrypting information; Equipped with The first communication device is a first device-side transmitting unit configured to transmit information indicating a first key among the first key information to an outside; The second communication device is a second device-side transmitting unit configured to transmit information indicating a second key among the second key information to an outside; The terminal device a first terminal side receiving unit that receives the information including first key identification information that identifies the first key from the first communication device; a second terminal side receiving unit that receives the information including second key identification information that identifies the second key from the second communication device; a third terminal side receiving unit that transmits a request to the first communication device and receives first encrypted connection information from the first communication device as a response to the request, the first encrypted connection information being connection information encrypted by the first communication device using the first key information, and the connection information being information for establishing a wireless connection with a specific device; a first key acquisition unit that acquires the first key by using the first key identification information included in the information received from the first communication device; a terminal side acquisition unit that, when the first encrypted connection information is received from the first communication device, decrypts the first encrypted connection information by using the first key acquired by using the first key identification information, and acquires the connection information; a second key acquisition unit that acquires the second key by using the second key identification information included in the information received from the second communication device; a generating unit that encrypts the acquired connection information by using the second key acquired by using the second key identification information to generate second encrypted connection information; a terminal side transmitting unit that transmits the second encrypted connection information to the second communication device; Equipped with The second communication device is a device side receiving unit for receiving the second encrypted connection information from the terminal device; a screen display unit that displays a confirmation screen for confirming whether or not to establish a wireless connection with the specific device when the second encrypted connection information is received from the terminal device; a device-side acquisition unit that, when the second encrypted connection information is received from the terminal device, decrypts the second encrypted connection information by using the second key information and acquires the connection information; an establishment unit that establishes a wireless connection with the specific device by using the acquired connection information when an operation indicating that a wireless connection with the specific device is to be established is accepted on the confirmation screen; A communication system comprising:

2. the first key information includes the first key which is a public key and a third key which is a private key; the second key information includes the second key which is a public key and a fourth key which is a private key; the first communication device encrypts the connection information by using the third key of the first key information; The communication system according to claim 1 , wherein the device-side acquisition unit decrypts the second encrypted connection information by using the fourth key of the second key information.

3. The first communication device further comprises: A first operation unit; a third device-side transmitting unit configured to transmit the first encrypted connection information to the terminal device as the response when a first predetermined operation is performed on the first operation unit after the request is received from the terminal device, and configured not to transmit the response to the terminal device when the first predetermined operation is not performed on the first operation unit after the request is received from the terminal device; The communication system according to claim 1 or 2, comprising:

4. the device-side acquisition unit decrypts the second encrypted connection information when accepting the operation indicating that a wireless connection with the specific device is to be established on the confirmation screen; The communication system according to claim 1 , wherein the second encrypted connection information is not decrypted until the operation indicating that a wireless connection with the specific device is established is received on the confirmation screen.

5. 4. The communication system according to claim 1, wherein the device-side acquisition unit decrypts the second encrypted connection information before accepting the operation indicating to establish a wireless connection with the specific device on the confirmation screen.

6. The first device side transmitting unit transmits the information indicating the first key to an unspecified number of devices. Send to The communication system according to claim 1 , wherein the second device side transmitting unit transmits the information indicating the second key to an unspecified number of devices.

7. the first device-side transmitting unit transmits the information indicating the first key to an unspecified number of devices by using an Advertise signal conforming to a Bluetooth standard version 4.0 or later; The communication system according to claim 6 , wherein the second device-side transmitting section transmits the information indicating the second key to an unspecified number of devices by using the Advertise signal.

8. The first device side transmitting unit further transmits first device identification information for identifying the first communication device, The second device side transmitting unit further transmits second device identification information for identifying the second communication device, The first terminal side receiving unit further receives the first device identification information from the first communication device, The second terminal side receiving unit further receives the second device identification information from the second communication device, the third terminal side receiving unit receives the first encrypted connection information from the first communication device identified by the received first device identification information; The communication system according to claim 1 , wherein the terminal side transmitting unit transmits the second encrypted connection information to the second communication device identified by the received second device identification information.

9. The terminal device further comprises: A display unit; a display control unit that causes the display unit to display a screen including an image corresponding to the first device identification information as a transmission source of the connection information and an image corresponding to the second device identification information as a transmission destination of the connection information; The communication system of claim 8 , comprising:

10. The communication system according to claim 1 , wherein the third terminal side receiving unit, the terminal side transmitting unit, and the device side receiving unit use communication according to a Bluetooth standard.

11. The communication system according to claim 1 , wherein the third terminal side receiving unit, the terminal side transmitting unit, and the device side receiving unit use communication according to a Wi-Fi standard.

12. A computer program for a terminal device, comprising: The terminal device computer is composed of the following parts: a first receiving unit that receives information including first key identification information for identifying a first key from a first communication device that stores first key information for encrypting and decrypting information, when the first communication device transmits information including first key identification information for identifying a first key among the first key information to an outside device; a second receiving unit that receives information including second key identification information that identifies a second key from a second communication device that stores second key information for encrypting and decrypting information, when the second communication device transmits information including second key identification information that identifies a second key among the second key information to an outside device; and a third receiving unit that transmits a request to the first communication device and receives first encrypted connection information from the first communication device as a response to the request, the first encrypted connection information being connection information encrypted by the first communication device using the first key information, and the connection information being information for establishing a wireless connection with a specific device; a first key acquisition unit that acquires the first key by using the first key identification information included in the information received from the first communication device; an acquisition unit that, when the first encrypted connection information is received from the first communication device, decrypts the first encrypted connection information by using the first key acquired by using the first key identification information, and acquires the connection information; a second key acquisition unit that acquires the second key by using the second key identification information included in the information received from the second communication device; a generating unit that encrypts the acquired connection information by using the second key acquired by using the second key identification information to generate second encrypted connection information; a transmission unit that transmits the second encrypted connection information to the second communication device, wherein the second communication device uses the second key information to decrypt the second encrypted connection information received from the terminal device, acquires the connection information, displays a confirmation screen for confirming whether or not to establish a wireless connection with the specific device, and when an operation indicating that a wireless connection with the specific device is to be established is accepted on the confirmation screen, establishes a wireless connection with the specific device using the acquired connection information; A computer program that functions as a

13. a second communication device, a memory that stores second key information for encrypting and decrypting information, the second key information being different from first key information stored in a first communication device that is different from the second communication device; A transmission unit that transmits information including second key identification information that identifies a second key of the second key information to an outside, the information indicative of the second key is received by a terminal device; the terminal device receives information including first key identification information identifying a first key of the first key information from the first communication device; sending a request to the first communication device and receiving first encrypted connection information from the first communication device in response to the request; obtaining the first key by using the first key identification information included in the information received from the first communication device; decrypting the first encrypted connection information by using the first key obtained by using the first key identification information, and obtaining connection information for establishing a wireless connection with a specific device; obtaining the second key by using the second key identification information included in the information received from the second communication device; encrypting the acquired connection information using the second key indicated by the information acquired using the second key identification information to generate second encrypted connection information; sending the second encrypted connection information to the second communication device; The transmitting unit; a receiving unit that receives the second encrypted connection information from the terminal device; a screen display unit that displays a confirmation screen for confirming whether or not to establish a wireless connection with the specific device when the second encrypted connection information is received from the terminal device; an acquisition unit that, when the second encrypted connection information is received from the terminal device, decrypts the second encrypted connection information by using the second key information and acquires the connection information; an establishment unit that establishes a wireless connection with the specific device by using the acquired connection information when an operation indicating that a wireless connection with the specific device is to be established is accepted on the confirmation screen; A second communication device comprising:

14. A first communication device, a memory that stores first key information for encrypting and decrypting information, the first key information being different from second key information stored in a second communication device different from the first communication device; a first transmission unit configured to transmit information including first key identification information for identifying a first key among the first key information to an outside, the information indicating the first key being received by a terminal device; a second transmission unit configured to receive a request from the terminal device and transmit first encrypted connection information to the terminal device as a response to the request, the first encrypted connection information is information obtained by encrypting connection information by the first communication device using the first key information, and the connection information is information for establishing a wireless connection with a specific device; The terminal device receiving information including second key identification information identifying a second key of the second key information from the second communication device; obtaining the first key by using the first key identification information included in the information received from the first communication device; decrypting the first encrypted connection information received from the first communication device using the first key obtained using the first key identification information to obtain the connection information; obtaining the second key by using the second key identification information included in the information received from the second communication device; encrypting the acquired connection information using the second key acquired using the second key identification information to generate second encrypted connection information; Sending the second encrypted connection information to the second communication device; the second communication device uses the second key information to decrypt the second encrypted connection information, acquires the connection information, and displays a confirmation screen for confirming whether or not to establish a wireless connection with the specific device; and, when an operation indicating that a wireless connection with the specific device is to be established is accepted on the confirmation screen, the second communication device establishes a wireless connection with the specific device using the acquired connection information. The second transmission unit; A first communication device comprising:

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