JP4168394B2 - Printer and printing system - Google Patents

Description

  The present invention relates to a printer and a printing system, and more particularly to a printer capable of restricting a place where printing data can be printed and a printing system having such a printer.

  In recent years, as a business model using a printer, a form in which a printer maker rents a printer free of charge to a user and the user pays the printer maker for the number of copies printed using the printer has been attracting attention. . In such a business model, in addition to charging according to the number of printed sheets, charging according to the usage period, charging according to the amount of ink used, and the like are conceivable.

  In addition, when print data is transmitted from a print client such as a computer to a printer, there is a demand for ensuring the security of the print data by limiting the position of the printer that can print the print data. In response to such a demand, a technique for encrypting print data from a computer and transmitting it to a printer and restricting the position of the printer where the encrypted print data can be decrypted is disclosed in Japanese Patent Application Laid-Open No. 11-331144. (Hereinafter referred to as Patent Document 1).

In the printing system of Patent Document 1, an encryption server manages an encryption key and a decryption key. Then, when acquiring the encryption key from the encryption server, the computer that transmits the data specifies the position where the decryption key may be transmitted, and encrypts the print data with this encryption key, Send to printer. The printer that has received the encrypted print data transmits the printer position to the encryption server, and the encryption server only decrypts the decryption key when the printer position matches the position specified by the computer. Is sent to the printer.
JP-A-11-331144

  In the business model for renting printers as described above free of charge, if a user resells a printer lent by a printer maker without permission, or rents it to another person, the printer maker charges for the use of the printer. You will not be able to. For this reason, the printer manufacturer wants to limit the place where the lent printer can be used, that is, the place where normal printing can be performed to the rented user's place.

  In the printing system of Patent Document 1, when transmitting encrypted data, only the position of the printer that can decrypt the data can be specified. Even if the printer is moved without permission, the position of the printer can be determined. If you specify it correctly, you can print.

  Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a printer capable of printing only at a location registered in advance and a printing system including such a printer.

In order to solve the above problems, a printer according to the present invention provides:
A printer that performs printing based on print data,
First printer position information acquisition means for acquiring printer position information for specifying a place where the printer is installed at the first time point, and using this as first printer position information;
Public key generation means for generating a public key using a passphrase including at least the first printer position information;
Public key holding means for holding the public key generated by the public key generation means;
Public key transmission means for transmitting the public key held in the public key holding means to the print client in response to a request from the print client;
An encrypted common key receiving means for receiving an encrypted common key generated by encrypting a common key using the public key from the print client;
Encrypted print data receiving means for receiving encrypted print data generated by encrypting print data using the common key from the print client;
Second printer position information acquisition means for acquiring printer position information for specifying a location where the printer is installed at the second time point, and using this as second printer position information;
A secret key generating means for generating a secret key using a passphrase including at least the second printer position information;
Using the secret key, decrypting the encrypted common key received by the encrypted common key receiving means, and obtaining a common key;
Print data acquisition means for decrypting the encrypted print data and acquiring print data using the common key acquired by the common key acquisition means;
It is characterized by providing.

  In this case, the second time point is after the encrypted common key is received by the encrypted common key receiving means and / or after the encrypted print data is received by the encrypted print data receiving means. There may be.

  Further, even when a secret key is generated when the public key is generated by the public key generation means, the secret key may be discarded without being saved.

  Further, even when the public key is generated when the secret key is generated by the secret key generation means, the public key may be discarded without being saved.

In addition to the first printer position information, the public key generation means generates a public key using a passphrase including device specific information that is specific information of the printer,
The secret key generation unit may generate a secret key using a passphrase including the device specific information in addition to the second printer position information.

Further, the encrypted common key and the encrypted print data are collectively transmitted as one file from the print client,
The encrypted common key receiving unit and the encrypted print data receiving unit may receive the encrypted common key and the encrypted print data by receiving the file.

On the other hand, the second time point is a time point when the printer is turned on.
The secret key generation means generates a secret key using a passphrase including at least the second printer position information, and a volatile memory in which stored contents are erased when the printer is turned off. Storing the secret key in a device;
The common key obtaining unit may obtain a secret key from the volatile storage device, decrypt the encrypted common key received by the encrypted common key receiving unit, and obtain a common key.

Further, the public key generated by the public key generation means is transmitted to a management server that manages the public key,
The print client may acquire the public key from the management server.

The printer control method according to the present invention includes:
A method for controlling a printer that performs printing based on print data,
Acquiring printer position information for specifying a location where the printer is installed at a first time point, and using the printer position information as first printer position information;
Generating a public key using a passphrase including at least the first printer position information;
Holding the generated public key in a public key holding means;
Sending a public key held in the public key holding means to the print client in response to a request from the print client;
Receiving from the print client an encrypted common key generated by encrypting a common key using the public key;
Receiving encrypted print data generated by encrypting print data using the common key from the print client;
Obtaining printer position information for specifying a place where the printer is installed at a second time point, and using the acquired printer position information as second printer position information;
Generating a secret key using a passphrase including at least the second printer position information;
Decrypting the encrypted common key using the secret key to obtain the common key;
Using the acquired common key to decrypt the encrypted print data and obtaining print data;
It is characterized by providing.

The printing system according to the present invention includes:
A printing system having a printer that performs printing based on print data and a print client connected to the printer,
The printer is
First printer position information acquisition means for acquiring printer position information for specifying a place where the printer is installed at the first time point, and using this as first printer position information;
Public key generation means for generating a public key using a passphrase including at least the first printer position information;
Public key holding means for holding the public key generated by the public key generation means;
With
The print client
A public key transmission request transmitting means for transmitting a public key transmission request for requesting transmission of a public key to the printer;
The printer is
Public key transmission request receiving means for receiving the public key transmission request transmitted from the print client;
Public key transmitting means for transmitting the public key held in the public key holding means to the print client in response to the received public key transmission request;
With
The print client
Public key receiving means for receiving the public key transmitted from the printer;
A common key generating means for generating a common key;
An encrypted common key generating means for encrypting the common key with the public key and generating an encrypted common key;
An encrypted common key transmitting means for transmitting the encrypted common key to the printer;
Print data generating means for generating print data;
Encrypted print data generation means for generating encrypted print data by encrypting the print data with the common key;
Encrypted print data transmission means for transmitting the encrypted print data to the printer;
With
The printer is
An encrypted common key receiving means for receiving the encrypted common key transmitted from the print client;
Encrypted print data receiving means for receiving the encrypted print data transmitted from the print client;
Second printer position information acquisition means for acquiring printer position information for specifying a location where the printer is installed at the second time point, and using this as second printer position information;
A secret key generating means for generating a secret key using a passphrase including at least the second printer position information;
Using the secret key, decrypting the encrypted common key received by the encrypted common key receiving means, and obtaining a common key;
Print data acquisition means for decrypting the encrypted print data and acquiring print data using the common key acquired by the common key acquisition means;
It is characterized by providing.

A control method of a printing system according to the present invention includes:
A control method for a printing system, comprising: a printer that performs printing based on print data; and a print client connected to the printer.
Acquiring printer position information for specifying a location where the printer is installed at a first time point, and using the printer position information as first printer position information;
Generating a public key using a passphrase including at least the first printer position information;
Holding the public key generated by the public key generating means in a public key holding means;
Transmitting a public key transmission request for requesting transmission of a public key from the print client to the printer;
Receiving the public key transmission request transmitted from the print client in the printer;
Transmitting the public key held in the public key holding unit from the printer to the print client in response to the received public key transmission request;
Receiving the public key transmitted from the printer at the print client;
Generating a common key in the print client;
In the print client, encrypting the common key with the public key to generate an encrypted common key;
Transmitting the encrypted common key from the print client to the printer;
Generating print data in the print client;
In the print client, encrypting the print data with the common key to generate encrypted print data;
Transmitting the encrypted print data from the print client to the printer;
Receiving the encrypted common key transmitted from the print client in the printer;
Receiving the encrypted print data transmitted from the print client in the printer;
Obtaining printer position information for specifying a place where the printer is installed at a second time point, and using the acquired printer position information as second printer position information;
Generating a secret key using a passphrase including at least the second printer position information;
Decrypting the received encrypted common key using the secret key to obtain a common key;
Using the acquired common key to decrypt the encrypted print data and obtaining print data;
It is characterized by providing.

  According to the present invention, it is possible to provide a printer that can print only at a location registered in advance, and a printing system including such a printer.

[First Embodiment]
First, based on FIG. 1, an outline of processing of the printing system according to the first embodiment of the present invention will be described. As shown in FIG. 1, in this embodiment, when the printer 30 is installed, a public key and a secret key are generated using a passphrase including at least printer position information indicating the position where the printer 30 is installed, and the printer 30 30 holds the public key but discards the private key (step [1]).

  When a public key is requested from the print client 20 that wants to send print data, the printer 30 sends the held public key to the print client 20 (step [2]). The print client 20 generates a common key using an appropriate random number or the like (step [3]), encrypts this common key with the acquired public key, and transmits it to the printer 30 as an encrypted common key ( Step [4]).

  When the printer 30 receives the encrypted common key, the printer 30 acquires the printer position information at that time, and generates a public key and a secret key using a passphrase including at least the printer position information (step [5]). . Then, the received encrypted common key is decrypted with the generated secret key (step [6]). At this time, the public key is discarded without being saved.

  If the position of the printer 30 has not been moved from the location where the public key was generated in step [1], the encrypted common key is decrypted and the common key can be acquired by the printer. However, if the position of the printer 30 has been moved from the location where the public key was generated in step [1], the printer 30 cannot decrypt the encrypted common key, and the printer cannot obtain the common key. .

  The print client 20 encrypts the print data using the common key generated in step [3], and transmits it to the printer 30 as encrypted print data (step [7]). Eventually, the encrypted print data can be decrypted using the common key obtained in step [6] in the printer 30 that has not been moved from the installed position, but cannot be decrypted in the moved printer 30. As a result, the position where the printer 30 can be used normally can be limited to the position where the public key is generated in step [1].

  As can be seen from this description, the timing at which the public key is transmitted from the printer 30 to the print client 20 may be any timing after the printer 30 is installed until a print request is generated. However, the step [5] for generating the secret key needs to be performed after the printer 30 receives the encrypted common key and / or after the printer 30 receives the encrypted print data.

  Further, the print client 20 may transmit the encrypted common key and the encrypted print data in this order, or conversely, the encrypted print data and the encrypted common key may be transmitted in this order. It may be. Alternatively, the encrypted common key and the encrypted print data may be transmitted simultaneously as one file.

  Next, the configuration of the printing system according to the present embodiment will be described with reference to FIG. FIG. 2 is a block diagram illustrating a hardware configuration of the printing system according to the present embodiment.

  As shown in FIG. 2, the printing system according to the present embodiment includes a print client 20 connected to the network 10 and a printer 30 also connected to the network 10. In the present embodiment, the network 10 is configured by the Internet using TCP / IP (transmission control protocol / internet protocol). However, the form of the network 10 is not limited to the Internet, and may be configured by a LAN such as Ethernet (registered trademark).

  The print client 20 is composed of various computers called a host computer and a personal computer, for example. In the present embodiment, in particular, the print client 20 generates encrypted print data obtained by encrypting print data, and transmits the encrypted print data to the printer 30 via the network 10. The number of print clients connected to the network 10 is arbitrary, and may be one or plural. The print client is not limited to a computer, and may be, for example, a digital camera that needs to print a captured image, a content server that stores print image data as content, or the like.

  In the present embodiment, the printer 30 is a so-called network printer. In the present embodiment, in particular, the printer 30 receives the encrypted print data from the print client 20, decrypts the encrypted print data with the common key, and performs printing.

  In the present embodiment, the printer 30 is directly connected to the network 10, and the printer 30 has a unique network address. Therefore, the print client 20 can transmit the encrypted print data to the printer 30 by designating this network address.

  In FIG. 2, the printer 30 is directly connected to the network 10, but may be connected via a printer server. The number of printers connected to the network 10 is arbitrary, and may be one or a plurality.

  FIG. 3 is a block diagram for explaining the internal configuration of the printer 30. As shown in FIG. 3, the printer 30 includes a central processing unit (CPU) 40, a random access memory (RAM) 42, and a read only memory (ROM) 44. Connected through. In addition, a communication interface 48 is connected to the internal bus 46, and the printer 30 is connected to the network 10 through the communication interface 48. Further, an interface 50 is connected to the internal bus 46, and a print engine 52 is connected to the interface 50.

  In addition, a position detector 54 is connected to the internal bus 46. The position detection unit 54 has a function of specifying the position where the printer 30 is installed. In the present embodiment, for example, a GPS (global positioning system) is used, and the latitude, longitude, and altitude of the position where the printer 30 is installed can be specified. It is said that the current GPS accuracy is about ± 10 m in each of latitude, longitude, and altitude.

  However, the position detection unit 54 is not limited to the configuration using the GPS. For example, when the printer 30 is connected to the network 10 by a wireless LAN, the position detection unit 54 is connected to the wireless base station in which the printer 30 is accommodated. Based on this, the position of the printer 30 may be specified. Alternatively, the position of the printer 30 may be specified using mobile communication technology such as PHS (Personal Handyphone System).

  In addition, both the GPS function and the PHS function are mounted on the position detection unit 54, and the installation position is normally detected using the GPS. However, if the position cannot be detected using the GPS due to radio wave conditions or the like, You may make it detect.

  Furthermore, the printer 30 according to the present embodiment includes an EEPROM (Electrically Erasable Programmable ROM) 56 connected to the internal bus 46 as a nonvolatile semiconductor memory device. The information stored in the EEPROM 56 is retained even when the printer 30 is turned off.

  In FIG. 3, the position detector 54 is built in the printer 30, but the position detector 54 may be externally attached to the printer 30 as shown in FIG. 4. For example, when necessary, a mobile phone equipped with GPS may be connected to the printer 30 so that the printer 30 has a position detection function.

  FIG. 5 is a block diagram for explaining the internal configuration of the print client 20. As shown in FIG. 5, the print client 20 according to this embodiment includes a computer main body 60 and a display 62.

  The computer main body 60 includes a CPU 64, a RAM 66, and a ROM 68, which are connected to each other via an internal bus 70. In addition, a communication interface 72 is connected to the internal bus 70, and the print client 20 is connected to the network 10 via the communication interface 72.

  Further, an interface 74 is connected to the internal bus 70, and a hard disk 76 that is a mass storage device is connected to the interface 74. In addition, an interface 78 is connected to the internal bus 70, and the above-described display 62 is connected via a cable 80 extending from the interface 78.

  Next, processing executed by the printer 30 and the print client 20 in order to realize the processing described with reference to FIG. 1 will be described in detail.

  First, a public key generation process executed by the printer 30 when the printer 30 is installed will be described with reference to FIG. FIG. 6 is a flowchart for explaining public key generation processing executed by the printer 30. This public key generation process is a process realized by the CPU 40 reading and executing a public key generation program stored in the ROM 44 of the printer.

  As shown in FIG. 6, first, the printer 30 requests the operator of the printer 30 to input installation authorization information (step S100). For example, the printer 30 displays an instruction to input installation authentication information on a display panel provided in the printer 30. For example, the operator operates the operation panel provided in the printer 30 and inputs the installation authentication information. For example, in the present embodiment, this installation authentication information is configured by a combination of an ID and password for installation authentication information. Therefore, the operator inputs the ID and password for the installation authentication information from the operation panel.

  Next, the printer 30 determines whether or not the input installation authentication information matches the installation authentication information registered in advance in the printer 30 (step S102). Specifically, as described above, it is determined whether the ID and password for installation authentication information input by the operator match the ID and password for installation authentication information registered in the printer 30 in advance. In the present embodiment, for example, when the printer 30 is shipped, the installation authentication information ID and password are stored in the EEPROM 56. The printer 30 can know the installation authentication information ID and password. It is a structure that only manufacturers of

  If the installation authentication information does not match (step S102: No), the printer 30 displays on the display panel of the printer 30 that the installation authentication information does not match (step S104), and this public key generation process Exit.

  On the other hand, when the installation authentication information matches (step S102: Yes), the printer 30 acquires device-specific information of the printer 30 (step S106). Here, the device unique information is identification information uniquely assigned to the printer 30 and includes, for example, a manufacturing serial number and a MAC address of the printer 30.

  Next, the printer 30 acquires the printer position information of the printer 30 at that time from the position detection unit 54 (step S108). Subsequently, the printer 30 creates a passphrase using the device specific information and the printer position information (step S110). Various methods for creating the passphrase can be considered. In this embodiment, the passphrase is created by simply connecting the printer position information to the device specific information. The passphrase may include data other than the device specific information and the printer position information.

  Next, the printer 30 generates a public key and a secret key by public key cryptography using the created passphrase (step S112). Public key cryptography has the property that if the same passphrase is used, the same key is generated even if the public key and the private key are generated again. Subsequently, the printer 30 stores and holds only the public key among the generated public key and secret key (step S114). Note that the private key is discarded without being saved. Thereby, the public key generation process according to the present embodiment ends.

  FIG. 7 is a diagram illustrating an example of the public key storage unit TB10 in which the public key is stored in step S114. In the present embodiment, the public key storage unit TB10 is formed in the EEPROM 56. Therefore, the public key stored in the public key storage unit TB10 is held in a nonvolatile manner even when the printer 30 is turned off.

  FIG. 8 is a flowchart for explaining public key request processing executed by the print client 20. This public key request process is a process realized by the CPU 64 reading and executing a public key request program stored in the ROM 68 or the hard disk 76 of the print client. The public key request process may be started at an arbitrary timing from when the printer 30 is installed to when print data is about to be transmitted. For example, in the present embodiment, when the user creates data to be printed and then instructs the print client 20 to perform printing with the printer 30, the print client 20 holds the public key of the printer 30. If not, try to start.

  As shown in FIG. 8, in this public key request process, the print client 20 first connects to the printer 30 (step S120). In the present embodiment, the print client 20 establishes a connection between the print client 20 and the printer 30 by designating the network address of the printer 30.

  Next, the print client 20 transmits authentication information to the printer 30 (step S122). In this embodiment, a combination of a client ID for specifying a print client and a password is used as the authentication information. Accordingly, the print client 20 transmits the client ID and password to the printer 30.

  Following this, the print client 20 receives an authentication result indicating whether or not the authentication has been accepted from the printer 30. Therefore, based on the authentication result, the print client 20 determines whether or not the authentication has been accepted by the printer 30 (step). S124).

  If the authentication is approved (step S124: Yes), the print client 20 transmits a public key acquisition request to the printer 30 (step S126). Then, it is determined whether a public key has been received from the printer 30 (step S128). If the public key has not been received from the printer 30 (step S128: No), this step S128 is repeated to stand by.

  On the other hand, when the public key is received from the printer 30 (step S128: Yes), the public key is stored (step S130). In the present embodiment, the print client 20 is provided with a public key table TB20 on the hard disk 76, and the acquired printer position information is stored and held in the public key table TB20.

  FIG. 9 is a diagram showing an example of the configuration of the public key table TB20. As shown in FIG. 9, the public key table TB20 includes an item D20 for storing information for specifying a printer, and an item D21 for storing the acquired public key in association with the printer. In this way, the public key table TB20 can hold public keys relating to a plurality of printers for each printer. Further, by storing the public key in the public key table TB20 of the hard disk 78 in this way, even when the print client 20 is turned off and turned on again, the public key obtained before that is used as it is. It can be read and used from.

  Next, the print client 20 ends the connection with the printer 30 (step S132).

  On the other hand, if it is determined in step S124 described above that the authentication has not been approved (step S124: No), the printer 30 has not been authenticated, and the user is informed that the public key cannot be acquired. (Step S134). Then, the connection with the printer 30 is terminated (step S132).

  Thus, the public key request process shown in FIG. 8 ends. Note that the authentication processing in step S122, step S124, and step S134 is not necessarily required, and this authentication processing can be omitted.

  Next, a public key transmission process executed by the printer 30 in response to the public key request process of the print client 20 will be described with reference to FIG. FIG. 10 is a flowchart for explaining public key transmission processing executed by the printer 30. This public key transmission process is a process realized by the CPU 40 reading and executing a public key transmission program stored in the ROM 44 of the printer. In the present embodiment, this public key transmission process is a process that is regularly executed at regular time intervals. The public key transmission process is a process corresponding to the public key request process described above.

  As shown in FIG. 10, the printer 30 waits for a connection from the print client 20, and establishes a connection with the print client 20 when a connection is requested from the print client 20 (step S220). Subsequently, the printer 30 determines whether authentication information has been received from the print client 20 (step S222). If the authentication information has not been received (step S222: No), the process of step S222 is repeated and the process waits.

  On the other hand, when the authentication information is received from the print client 20 (step S222: Yes), it is determined whether the authentication information matches the authentication information registered in advance in the printer 30 (step S224). Specifically, as described above, since the print client ID and password are transmitted as authentication information from the print client 20, the print client ID and password are stored in the printer 30 in advance. Determine if it matches the password.

  If the authentication information does not match (step S224: No), the printer 30 transmits an authentication result indicating that the authentication has not been accepted to the print client 20 (step S226). In step S236, which will be described later, printing is performed. The connection with the client 20 is terminated (step S236). On the other hand, if the authentications match (step S224: Yes), the printer 30 transmits an authentication result indicating that the authentication is accepted to the print client 20 (step S228).

  Next, the printer 30 determines whether a public key acquisition request has been received from the print client 20 (step S230). If this public key acquisition request has not been received (step S230: No), the processing of step S230 is repeated and waits.

  When the public key acquisition request is received (step S230: Yes), the printer 30 reads and acquires the public key from the public key storage unit TB10 of the EEPROM 56 (step S232). Subsequently, the printer 30 transmits the acquired public key to the print client 20 (step S234). Then, the connection with the print client 20 is terminated (step S236), and the process returns to the above-described step S220.

  As described above, the process of authenticating the print client 20 can be omitted. In this case, the processes of step S222, step S224, step S226, and step S228 are omitted.

  Next, processing of the print client 20 and the printer 30 when the print client 20 transmits a print request to the printer 30 will be described in detail.

  FIGS. 11 and 12 are flowcharts for explaining print request processing executed by the print client 20. This print request processing is realized by the CPU 64 reading and executing a print request program stored in the ROM 68 or the hard disk 76 of the print client. In the present embodiment, this print request process is a process that is started when the user creates data to be printed and instructs the print client 20 to perform printing with the printer 30.

  As shown in FIG. 11, the print client 20 generates a common key using, for example, a random number (step S140). Various common key cryptosystems are known, and examples include DES (data encryption standard), triple DES, and Rijndael (Rhinedale).

  Next, the print client 20 reads and acquires the public key of the printer 30 from the public key table TB20 (step S142). Subsequently, the print client 20 encrypts the common key using the public key generated in step S140, and generates an encrypted common key (step S144).

  Next, the print client 20 transmits this encrypted common key to the printer 30 (step S146). Specifically, the network address of the printer 30 is designated and the encryption common key is sent to the network 10.

  Next, as shown in FIG. 12, the print client 20 generates print data (step S150). This print data is data necessary for the printer 30 to actually perform printing.

  Next, the print client 20 encrypts the print data using the common key generated in step S140, and generates encrypted print data (step S152). Subsequently, the print client 20 transmits the encrypted print data to the printer 30 (step S154). Specifically, the network address of the printer 30 is designated and the encrypted print data is sent to the network 10. Then, the print client 20 discards the common key (step S155).

  Next, the print client 20 determines whether print result information has been received from the printer 30 (step S156). If the print result information has not been received (step S156: No), the process of step S156 is repeated and waits. On the other hand, if print result information has been received (step S156: Yes), it is determined whether the print result information is a print completion notification (step S158).

  If this print result information is a print completion notification (step S158: Yes), this means that printing has been completed normally by the printer 30, so the user is notified that printing has been completed by the printer 30. (Step S160). On the other hand, if the received print result information is not a print completion notification (step S158: No), it is determined whether or not the print result information is a decipherable notification (step S162).

  If the print result information is an unreadable notification (step S162: Yes), the user is notified that printing has not been performed because the printer 30 could not decode the print transmission data (step S164). . On the other hand, if the print result information is not an undecipherable notification (step S162: No), it is considered that there is some other error, so the user is notified according to the type of error (step S166).

  The print request processing in the print client 20 is terminated by the notifications in step S160, step S164, and step S166.

  Next, a print execution process executed by the printer 30 in response to the print request process of the print client 20 will be described with reference to FIGS. 13 and 14. FIGS. 13 and 14 are flowcharts for explaining the print execution process executed by the printer 30. This print execution process is a process realized by the CPU 40 reading and executing a print execution program stored in the ROM 44 of the printer 30. In the present embodiment, this print execution process is a process that is regularly executed.

  As shown in FIG. 13, the printer 30 determines whether an encrypted common key has been received from the network 10 (step S180). If the encrypted common key has not been received (step S180: No), the process of step S180 is repeated and waits.

  On the other hand, when the encrypted common key is received (step S180: Yes), the printer 30 acquires its own device unique information (step S182). Subsequently, the printer 30 acquires the printer position information of the printer 30 at that time from the position detection unit 54 (step S184). In this way, the printer position information is acquired from the position detection unit 54 each time, because there is a possibility that the printer 30 is moved from the place where it was originally installed to another place. This is to prevent the printer 30 from printing.

  Next, the printer 30 creates a passphrase based on the device specific information and the printer position information (step S186). This passphrase creation method needs to be the same as step S110 in the public key generation process described above. This is because if the passphrase is different, the encrypted common key transmitted from the print client 20 cannot be decrypted with the secret key.

  Next, the printer 30 uses the passphrase to generate a public key and a secret key by public key cryptography (step S188). Subsequently, the printer 30 uses the generated secret key to decrypt the received encrypted common key and obtain the common key (step S190). Subsequently, the printer 30 discards the secret key used in step S190 (step S191).

  Next, the printer 30 determines whether or not the encrypted common key has been decrypted using the secret key (step S192). If the decryption cannot be performed (step S192: No), a decryption impossible notification is transmitted as print result information to the print client 20 (step S194), and the process returns to the above-described step S180. That is, when the public key generation process is executed and the place where the current print execution process is executed is different, the printer 30 has been moved to another place. A private key that decrypts the key cannot be generated. For this reason, the printer 30 cannot perform printing.

  On the other hand, if the encrypted common key can be decrypted using the secret key (step S192: Yes), the printer 30 determines whether or not the encrypted print data has been received from the print client 20, as shown in FIG. Judgment is made (step S200). If the encrypted print data has not been received (step S200: No), the process of step S200 is repeated and waits.

  On the other hand, when the encrypted print data is received (step S200: Yes), the printer 30 decrypts the received encrypted print data with the common key decrypted in step S190, and acquires the print data (step S200). S202). Subsequently, the printer 30 executes printing by driving the print engine 52 based on the obtained print data (step S204). Specifically, the print data is interpreted in language, and print request data suitable for the print engine 52 is generated. Then, by transmitting this print request data to the print engine 52, the print engine 52 performs printing on a print sheet or the like.

  When this printing is normally completed, the printer 30 transmits a print completion notification indicating that the printing has been normally completed to the print client 20 as print result information (step S206). Subsequently, the printer 30 discards the common key acquired in step S190 (step S208). And it returns to the process of step S180 mentioned above.

  FIG. 15 is a functional block diagram showing a configuration when the above-described processes are realized by hardware. As shown in FIG. 15, in the printer 30, the public key generation unit 100 acquires printer position information from the position detection unit 54 and uses a passphrase including the printer position information and device specific information to Is generated. The public key holding unit holds the public key generated by the public key generation unit 100.

  In the print client 20, the public key request unit 200 generates a public key transmission request for requesting transmission of the public key and transmits it to the printer 30 at an arbitrary timing. In the printer 30 that has received this public key transmission request, the public key transmission unit 104 reads out the public key held in the public key holding unit 102 and transmits it to the print client 20.

  In the print client 20, the public key transmitted from the printer 30 is received by the public key receiving unit 202. The common key generation unit 204 generates a common key, and the encryption common key generation unit 206 encrypts the common key with a public key to generate an encryption common key. Then, the encrypted common key transmission unit 208 transmits the generated encrypted common key from the print client 20 to the printer 30.

  Furthermore, in the print client 20, the print data generation unit 210 generates print data, and the encrypted print data generation unit encrypts the print data using a common key to generate encrypted print data. Then, the encrypted print data transmission unit 214 transmits the encrypted print data from the print client 20 to the printer 30.

  On the other hand, in the printer 30, the encrypted common key transmitted from the print client 20 is received by the encrypted common key receiving unit 106, and the encrypted print data transmitted from the print client 20 is encrypted. The data is received by the data receiving unit 108. Further, the secret key generation unit 110 acquires printer position information from the position detection unit 54, and generates a secret key using a passphrase including the printer position information and device specific information.

  The common key acquisition unit 112 uses the secret key generated by the secret key generation unit 110 to decrypt the encrypted common key received by the encryption common key reception unit 106 and acquires the common key. Then, the print data acquisition unit 114 uses the acquired common key to decrypt the encrypted print data received by the encrypted print data reception unit 108 and acquire the print data. The print execution unit 116 prints the print data by actually driving the print engine 52.

  As described above, according to the printing system according to the present embodiment, the printer 30 can perform normal printing only at the place where the public key is generated. Therefore, the place where the printer 30 can be used is the place where the public key is generated. It can be limited to. That is, in the printer 30 according to the present embodiment, when the printer 30 is moved to a location different from the location where the public key is generated, the encrypted common key transmitted from the print client 20 cannot be correctly decrypted. The key cannot be obtained. For this reason, the encrypted print data encrypted with the common key cannot be decrypted on the print client 20 side.

  Moreover, in the present embodiment, the print data is encrypted using a common key. In general, it is said that the speed of decrypting data with a common key using a common key cryptosystem is about 1000 times faster than the speed of decrypting data with a secret key based on a public key cryptosystem. For this reason, print data with a large amount of data can be quickly decrypted using the common key.

  Accordingly, according to the printing system according to the present embodiment, the print client 20 can substantially limit the printers that can print the encrypted print data that has been encrypted and transmitted. It is possible to avoid printing by a printer at a position not intended by the user of the client 20.

[Second Embodiment]
In the first embodiment described above, the secret key used for decrypting the encrypted common key is discarded in step S191. However, there may be a case where some cost such as a communication cost occurs when the position detection unit 54 acquires the printer position information. In such a case, it is advantageous for the user to reduce the number of times the printer position information is acquired as much as possible. Therefore, in the present embodiment, when the power of the printer 30 is turned on, the printer position information is obtained from the position detection unit 54, a secret key is generated, and this is generated when the power is turned off. Is stored in the RAM 42 which is a volatile storage device from which the stored contents are erased. When a secret key is required, the printer 30 reads the secret key from the RAM 42 and uses it.

FIG. 16 is a flowchart for explaining a secret key generation process executed by the printer 30. This secret key generation process is a process realized by the CPU 40 reading and executing a secret key generation program stored in the ROM 44 of the printer 30. In the present embodiment, this secret key generation process is a process that is started when the power of the printer 30 is turned on.

  As shown in FIG. 16, the printer 30 acquires its own device specific information (step S300). Subsequently, the printer 30 acquires the printer position information of the printer 30 at that time from the position detection unit 54 (step S302). In this way, the printer position information is acquired from the position detection unit 54 each time, because there is a possibility that the printer 30 is moved from the place where it was originally installed to another place. This is to prevent the printer 30 from printing.

  Next, the printer 30 creates a passphrase based on the device specific information and the printer position information (step S304). This passphrase creation method needs to be the same as step S110 in the public key generation process of the first embodiment. This is because if the passphrase is different, the encrypted common key transmitted from the print client 20 cannot be decrypted with the secret key.

  Next, the printer 30 generates a public key and a secret key by public key cryptography using the passphrase (step S306). Subsequently, the printer 30 stores the generated secret key in the RAM 30 that is a volatile storage device (step S308). Thereby, the secret key generation process in the present embodiment is completed.

  FIG. 17 is a diagram illustrating an example of the secret key storage unit TB30 in which the secret key is stored in step S308. In the present embodiment, the secret key storage unit TB30 is formed in the RAM. For this reason, the secret key stored in the secret key storage unit TB30 is automatically deleted when the printer 30 is turned off.

  Next, a print execution process executed by the printer 30 in response to the print request process of the print client 20 will be described with reference to FIG. FIG. 18 is a flowchart for explaining a print execution process executed by the printer 30. This print execution process is a process realized by the CPU 40 reading and executing a print execution program stored in the ROM 44 of the printer 30. In the present embodiment, this print execution process is a process that is regularly executed.

  As shown in FIG. 18, the printer 30 determines whether an encrypted common key is received from the network 10 (step S320). If the encrypted common key has not been received (step S320: No), the process of step S320 is repeated and waits.

  On the other hand, when the encrypted common key is received (step S320: Yes), the printer 30 reads and acquires the secret key from the RAM 42 (step S322). Subsequently, the printer 30 decrypts the received encrypted common key using the obtained secret key, and obtains the common key (step S324).

  Next, the printer 30 determines whether or not the encrypted common key has been decrypted using the secret key (step S326). If the decryption cannot be performed (step S326: No), a notification that the decryption is impossible is transmitted as print result information to the print client 20 (step S328), and the process returns to the above-described step S320. That is, if the location when the public key generation process is executed and the time when the printer 30 is turned on this time are different, the printer 30 has been moved to another location. A secret key for decrypting the common key cannot be generated. For this reason, the printer 30 cannot perform printing.

  On the other hand, when the encrypted common key can be decrypted using the secret key (step S326: Yes), the same processing as in FIG. 14 in the first embodiment described above is executed.

  Since the other processes executed by the printing system according to the present embodiment are the same as those in the first embodiment described above, detailed description thereof is omitted.

  As described above, according to the printing system according to the present embodiment, when the printer 30 is turned on, the printer position information is acquired, a secret key is generated, and this is stored in the RAM 42. Therefore, when a secret key is required, the secret key can be read from the RAM 42. This eliminates the need to acquire printer position information from the position detection unit 54 each time.

  Moreover, since the secret key is stored in the RAM 42 whose contents are erased when the printer 30 is turned off, when the printer 30 is turned on after the printer 30 is moved, The printer 30 can no longer perform normal printing. For this reason, the place where the printer 30 can be used can be limited to the place where the public key is generated.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible. For example, in the above-described embodiment, the device unique information is used as the passphrase in addition to the printer position information, but the device unique information is not necessarily required.

  In the above-described embodiment, the encrypted common key and the encrypted print data are separately transmitted from the print client 20 to the printer 30. However, these are collectively collected as one file from the print client 20 to the printer 30. You may make it transmit. In this case, the printer 30 acquires the encrypted common key and the encrypted print data from this file.

  Furthermore, as shown in FIG. 19, a management server that manages the public key of the printer 30 may be provided on the network 10. In this case, the printer 30 that has generated the public key transmits the public key to the management server 300 without holding the public key. When the management server 300 holds this public key and receives a request for transmitting the public key from the print client 20, the management server 300 transmits the public key of the printer 30 to the print client 20. Other parts are the same as those in the above-described embodiment.

  Further, although the printer has been described as an example of the data receiving device that restricts the usable position, the present invention is not limited to the printer. Further, the data transmission apparatus is not limited to the print client.

  For example, the data transmission device in the data transmission / reception system may be a digital camera for photographing an image, and the data reception device may be a data server that stores image data photographed by the digital camera. In this case, the common key transmitted from the digital camera is encrypted using the public key received from the data server, and the data server receiving the encrypted common key obtains the common key by the above-described method. To do. The data transmitted from the digital camera is encrypted using a common key, and the data server that receives the encrypted data decrypts the data using the acquired common key and obtains the data. To do. When the data server can decrypt the data, the data server accumulates the data.

  In the above-described embodiment, the case where the print medium of the printer 30 is a print sheet has been described as an example. However, the print medium is not limited to this, and may be another print medium such as an OHP sheet. The present invention can be applied.

  Further, for each process described in the above embodiment, a program for executing each process is recorded on a recording medium such as a flexible disk, a CD-ROM (Compact Disc-Read Only Memory), a ROM, or a memory card. Thus, it can be distributed in the form of a recording medium. In this case, the above-described embodiment can be realized by causing the print client 20 and / or the printer 30 to read and execute the recording medium on which the program is recorded.

  The print client 20 and / or the printer 30 may include other programs such as an operating system and another application program. In this case, other programs provided in the print client 20 and / or the printer 30 are utilized, and processing equivalent to that in the above-described embodiment is realized from the programs provided in the print client 20 and / or the printer 30 on the recording medium. An instruction that calls the program may be recorded.

  Furthermore, such a program can be distributed not as a recording medium but as a carrier wave through a network. The program transmitted in the form of a carrier wave on the network is taken into the print client 20 and / or the printer 30, and the above-described embodiment can be realized by executing this program.

  Also, when a program is recorded on a recording medium or transmitted as a carrier wave on a network, the program may be encrypted or compressed. In this case, the print client 20 and / or the printer 30 that read the program from the recording medium or the carrier wave needs to execute the program after decoding or decompressing the program.

FIG. 3 is a diagram for explaining how to use a common key, a public key, and a secret key in the printing system according to the first embodiment of the present invention. 1 is a block diagram illustrating an overall configuration of a printing system according to a first embodiment. FIG. 2 is a block diagram illustrating a hardware configuration of the printer according to the first embodiment. FIG. 9 is a block diagram for explaining a modified example of the hardware configuration of the printer. FIG. 3 is a diagram illustrating a hardware configuration of a print client according to the first embodiment. The figure which shows the flowchart explaining the public key production | generation process in 1st Embodiment. The figure which shows an example of a structure of the public key storage part in 1st Embodiment. The figure which shows the flowchart explaining the public key request | requirement process in 1st Embodiment. The figure which shows an example of a structure of the public key table in 1st Embodiment. The figure which shows the flowchart explaining the public key transmission process in 1st Embodiment. FIG. 6 is a first diagram illustrating a flowchart for describing print request processing according to the first embodiment. FIG. 6 is a second flowchart illustrating a print request process according to the first embodiment. FIG. 6 is a first flowchart illustrating a flowchart for explaining print execution processing according to the first embodiment; FIG. 6 is a second diagram illustrating a flowchart for describing print execution processing according to the first embodiment. The functional block diagram explaining the case where the process of the printing system which concerns on 1st Embodiment is implement | achieved by the hardware. The figure which shows the flowchart explaining the secret key generation process in 2nd Embodiment. The figure which shows an example of the secret key storage part in 2nd Embodiment. The figure which shows the flowchart explaining the printing execution process in 2nd Embodiment. The figure explaining the modification of 1st Embodiment and 2nd Embodiment.

Explanation of symbols

10 Network 20 Print Client 30 Printer 40 CPU
42 RAM
44 ROM
46 Internal bus 48, 50 Interface 52 Print engine 54 Position detector 56 EEPROM
60 Computer body 62 Display 64 CPU
66 RAM
68 ROM
70 Internal bus 72, 74, 78 Interface 76 Hard disk

Claims (11)

A printer that performs printing based on print data,
In the first time, obtains the printer position information for specifying a location which is installed in the printer, it is the first printer position information, and the first printer position information acquisition means,
Public key generation means for generating a public key using a passphrase including at least the first printer position information;
Public key holding means for holding the public key generated by the public key generation means;
Public key transmission means for transmitting the public key held in the public key holding means to the print client in response to a request from the print client;
An encrypted common key receiving means for receiving an encrypted common key generated by encrypting a common key using the public key from the print client;
Encrypted print data receiving means for receiving encrypted print data generated by encrypting print data using the common key from the print client;
Second printer position information acquisition means for acquiring printer position information for specifying a location where the printer is installed at the second time point, and using this as second printer position information;
A secret key generating means for generating a secret key using a passphrase including at least the second printer position information;
Using the secret key, decrypting the encrypted common key received by the encrypted common key receiving means, and obtaining a common key;
Print data acquisition means for decrypting the encrypted print data and acquiring print data using the common key acquired by the common key acquisition means;
A printer comprising: The second time, after receiving the encrypted common key with the encrypted common key receiving means, and / or Ru der after receiving the encrypted print data in the encrypted print data receiving means, The printer according to claim 1.   3. The secret key is discarded without being saved even if a secret key is generated when the public key is generated by the public key generation means. The printer described.   The public key is discarded without being saved even if a public key is generated when the secret key is generated by the secret key generating means. A printer according to any of the above. The public key generation means generates a public key using a passphrase including device specific information that is unique information of the printer in addition to the first printer position information,
The secret key generation means also generates a secret key using a passphrase including the device specific information in addition to the second printer position information.
The printer according to claim 1, wherein the printer is a printer. The encrypted common key and the encrypted print data are collectively transmitted as one file from the print client,
The encrypted common key receiving unit and the encrypted print data receiving unit receive the encrypted common key and the encrypted print data by receiving the file.
The printer according to any one of claims 1 to 5, wherein: The second time point is a time when the power source of the printer is turned on,
The secret key generation means generates a secret key using a passphrase including at least the second printer position information, and a volatile memory in which stored contents are erased when the printer is turned off. Storing the secret key in a device;
The common key obtaining unit obtains a secret key from the volatile storage device, decrypts the encrypted common key received by the encrypted common key receiving unit, and obtains a common key;
The printer according to claim 1. The public key generated by the public key generation means is transmitted to a management server that manages the public key,
The print client obtains the public key from the management server;
The printer according to claim 1, wherein the printer is a printer. A method for controlling a printer that performs printing based on print data,
In a first time, a step of acquiring the printer position information for specifying a location which is installed in the printer, to do this the first printer position information,
Generating a public key using a passphrase including at least the first printer position information;
Holding the generated public key in a public key holding means;
Sending a public key held in the public key holding means to the print client in response to a request from the print client;
Receiving from the print client an encrypted common key generated by encrypting a common key using the public key;
Receiving encrypted print data generated by encrypting print data using the common key from the print client;
Obtaining printer position information for specifying a place where the printer is installed at a second time point, and using the acquired printer position information as second printer position information;
Generating a secret key using a passphrase including at least the second printer position information;
Decrypting the encrypted common key using the secret key to obtain the common key;
Using the acquired common key to decrypt the encrypted print data and obtaining print data;
A printer control method comprising: A printing system having a printer that performs printing based on print data and a print client connected to the printer,
The printer is
In the first time, obtains the printer position information for specifying a location which is installed in the printer, it is the first printer position information, and the first printer position information acquisition means,
Public key generation means for generating a public key using a passphrase including at least the first printer position information;
Public key holding means for holding the public key generated by the public key generation means;
With
The print client
A public key transmission request transmitting means for transmitting a public key transmission request for requesting transmission of a public key to the printer;
The printer is
Public key transmission request receiving means for receiving the public key transmission request transmitted from the print client;
Public key transmitting means for transmitting the public key held in the public key holding means to the print client in response to the received public key transmission request;
With
The print client
Public key receiving means for receiving the public key transmitted from the printer;
A common key generating means for generating a common key;
An encrypted common key generating means for encrypting the common key with the public key and generating an encrypted common key;
An encrypted common key transmitting means for transmitting the encrypted common key to the printer;
Print data generating means for generating print data;
Encrypted print data generation means for generating encrypted print data by encrypting the print data with the common key;
Encrypted print data transmission means for transmitting the encrypted print data to the printer;
With
The printer is
An encrypted common key receiving means for receiving the encrypted common key transmitted from the print client;
Encrypted print data receiving means for receiving the encrypted print data transmitted from the print client;
Second printer position information acquisition means for acquiring printer position information for specifying a location where the printer is installed at the second time point, and using this as second printer position information;
A secret key generating means for generating a secret key using a passphrase including at least the second printer position information;
Using the secret key, decrypting the encrypted common key received by the encrypted common key receiving means, and obtaining a common key;
Print data acquisition means for decrypting the encrypted print data and acquiring print data using the common key acquired by the common key acquisition means;
A printing system comprising: A control method for a printing system, comprising: a printer that performs printing based on print data; and a print client connected to the printer.
In a first time, a step of acquiring the printer position information for specifying a location which is installed in the printer, to do this the first printer position information,
Generating a public key using a passphrase including at least the first printer position information;
Holding the public key generated by the public key generating means in a public key holding means;
Transmitting a public key transmission request for requesting transmission of a public key from the print client to the printer;
Receiving the public key transmission request transmitted from the print client in the printer;
Transmitting the public key held in the public key holding unit from the printer to the print client in response to the received public key transmission request;
Receiving the public key transmitted from the printer at the print client;
Generating a common key in the print client;
In the print client, encrypting the common key with the public key to generate an encrypted common key;
Transmitting the encrypted common key from the print client to the printer;
Generating print data in the print client;
In the print client, encrypting the print data with the common key to generate encrypted print data;
Transmitting the encrypted print data from the print client to the printer;
Receiving the encrypted common key transmitted from the print client in the printer;
Receiving the encrypted print data transmitted from the print client in the printer;
Obtaining printer position information for specifying a place where the printer is installed at a second time point, and using the acquired printer position information as second printer position information;
Generating a secret key using a passphrase including at least the second printer position information;
Decrypting the received encrypted common key using the secret key to obtain a common key;
Using the acquired common key to decrypt the encrypted print data and obtaining print data;
A control method for a printing system, comprising:

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