Image forming apparatus, print authentication system, consumables, and print authentication method

Abstract

This technology, which digitally signs activation data including challenge data with a private key and verifies the validity of the transmitted content using a public key, will be applied to authentication between an image forming apparatus and its consumables. [Solution] The control unit 110 sends an authentication process start request to the IC chip 210, and the IC chip 210 generates challenge data and sends it to the control unit 110. Based on the challenge data, the control unit 110 generates activation data, generates a digital signature using the private key 123 on the activation data, and sends the activation data and digital signature to the IC chip 210. The IC chip 210 uses the public key 233 to verify the validity of the digital signature and determines whether or not to allow access to the data based on the result of the validity verification.

Description

Technical Field

[0001] The present disclosure relates to an image forming apparatus, a print authentication system, a consumable, and a print authentication method for managing data access between the image forming apparatus and the consumable.

Background Art

[0002] Patent Document 1 discloses a technology in which a security component that has received an authentication request from a host transmits challenge data to the host, and the host digitally signs activation data including the challenge data with a private key and transmits the signed data to the security component. In this technology, the security component verifies the validity of the digital signature using a public key corresponding to the private key, and permits access to the data.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 1 does not specifically disclose a case where the technology of digitally signing activation data including challenge data with a private key for transmission and then verifying the validity of the digital signature using a public key is applied to authentication between an image forming apparatus and a consumable.

[0005] An object of the present disclosure is to provide an image forming apparatus, a print authentication system, a consumable, and a print authentication method that can apply a technology of verifying the validity of content, which is obtained by digitally signing activation data including challenge data with a private key and transmitting the signed content, using a public key, to authentication between the image forming apparatus and the consumable.

Means for Solving the Problems

[0006] To achieve the above objective, the first disclosure of this application relates to the following technologies. An image forming apparatus comprising a control unit, a main memory for storing a first private key, and a consumable having an IC chip for storing a first public key corresponding to the first private key, wherein the control unit performs a first transmission process to send a first authentication request to the IC chip; the IC chip performs a second transmission process to generate first challenge data and send it to the control unit in response to the transmission of the first authentication request by the first transmission process; the control unit performs a third transmission process to generate first activation data based on the first challenge data sent by the second transmission process, generate a first digital signature using the first private key on the first activation data, and send the first activation data and the first digital signature to the IC chip; the IC chip performs a first verification process to decrypt the first digital signature received from the control unit by the third transmission process using the first public key, and to determine whether the decrypted data obtained matches the first activation data received from the control unit; and a first access determination process to determine whether to allow access to the data stored in the IC chip according to the result of the first verification process.

[0007] In the image forming apparatus disclosed in the first disclosure of this application, consumables perform authentication of the image forming apparatus. First, when the control unit of the image forming apparatus transmits a first authentication request to the IC chip in the first transmission process, the IC chip generates first challenge data in response to the first authentication request and transmits it to the control unit.

[0008] The control unit generates first activation data based on the first challenge data, and generates a first digital signature using the first private key, which has been previously associated with the first public key, in the first activation data. The generated first activation data and first digital signature are transmitted to the IC chip in the third transmission process.

[0009] In the first verification process, the IC chip verifies the validity of the transmitted first digital signature using the first public key associated with the first private key. Furthermore, based on the verification result, the IC chip determines in the first access determination process whether or not to allow access to the data stored in the IC chip. As a result, if a correct first digital signature is made using the first private key, the data in the IC chip can be accessed; if a correct first digital signature is not made, the data in the IC chip cannot be accessed.

[0010] As described above, according to the present disclosure, the technology for verifying the validity of content transmitted after digitally signing the validity data, including challenge data, with a private key using a public key can be applied to authentication between an image forming apparatus and consumables.

[0011] Furthermore, in order to achieve the above objectives, the second disclosure of this application relates to the following technology: A print authentication system comprising an image forming apparatus having a control unit, and a consumable item detachable from the image forming apparatus, the consumable item having an IC chip, wherein the control unit performs a sixth transmission process to generate a second challenge data and transmit it to the IC chip as a second authentication request; the IC chip performs a seventh transmission process to generate a second activation data based on the second challenge data transmitted by the sixth transmission process, generate a second digital signature using a second private key on the second activation data, and transmit the second activation data and the second digital signature to the control unit; the control unit performs a second verification process to verify the validity of the second digital signature transmitted by the seventh transmission process using a second public key corresponding to the second private key, and a second access determination process to determine whether or not to allow access to the image forming apparatus according to the result of the validity verification by the second verification process.

[0012] The print authentication system disclosed in the second part of this application allows an image forming apparatus to authenticate consumables. First, when the IC chip transmits a second authentication request to the control unit of the image forming apparatus in the fifth transmission process, the control unit generates second challenge data in response to the second authentication request and transmits it to the IC chip.

[0013] The IC chip generates second activation data based on the second challenge data, and uses the second private key, which has been previously associated with the second public key, in the second activation data to generate a second digital signature. The generated second activation data and second digital signature are sent to the control unit in the seventh transmission process.

[0014] In the second verification process, the control unit verifies the validity of the transmitted second digital signature using the second public key associated with the second private key. Furthermore, based on the verification result, the control unit determines in the second access determination process whether or not to permit access to the image forming apparatus. As a result, if a correct second digital signature is made using the second private key, access to the image forming apparatus is permitted; if a correct second digital signature is not made, access to the image forming apparatus is denied.

[0015] As described above, according to the present disclosure, the technology for verifying the validity of content transmitted after digitally signing the validity data, including challenge data, with a private key using a public key can be applied to authentication between an image forming apparatus and consumables.

[0016] Furthermore, in order to achieve the above objective, the third disclosure of this application provides a consumable that is detachably configured for an image forming apparatus and includes an IC chip and a memory control unit that controls information input and output to the IC chip, wherein the memory control unit performs a data transmission process that generates challenge data and transmits it to the image forming apparatus in response to the transmission of an authentication request transmitted from the image forming apparatus; an acquisition process that receives and acquires valid data generated based on the challenge data transmitted by the data transmission process and a digital signature generated using a private key on the valid data from the image forming apparatus; a verification process that verifies the validity of the digital signature acquired by the acquisition process using a public key corresponding to the private key; and an access determination process that determines whether or not to permit access to the data stored in the IC chip according to the result of the validity verification by the verification process.

[0017] Furthermore, in order to achieve the above objective, the fourth disclosure of this application provides a method for printing authentication of a consumable that is detachable from an image forming apparatus having a control unit and having an IC chip, the method comprising: a first transmission step in which the control unit transmits a first authentication request to the IC chip; a second transmission step in which the IC chip generates first challenge data in response to the transmission of the first authentication request and transmits it to the control unit; a third transmission step in which the control unit generates first activation data based on the first challenge data, generates a first digital signature using a first private key on the first activation data, and transmits the first activation data and the first digital signature to the IC chip; a first verification step in which the IC chip verifies the validity of the first digital signature using a first public key corresponding to the first private key; and a first access determination step in which, according to the result of the validity verification by the first verification step, determines whether or not to permit access to data stored in the IC chip.

[0018] Furthermore, in order to achieve the above objective, the fifth disclosure of this application provides a method for printing authentication of a consumable that is detachable from an image forming apparatus having a control unit and having an IC chip, comprising: a fifth transmission step of transmitting a second authentication request to the control unit via the IC chip; a sixth transmission step of the control unit generating second challenge data in response to the transmission of the second authentication request and transmitting it to the IC chip; a seventh transmission step of the IC chip generating second activation data based on the second challenge data, generating a second digital signature using a second private key on the second activation data, and transmitting the second activation data and the second digital signature to the control unit; a second verification step of the control unit verifying the validity of the second digital signature using a second public key corresponding to the second private key; and a second access determination step of determining whether or not to permit access to the image forming apparatus according to the result of the validity verification by the second verification step. [Effects of the Invention]

[0019] According to this disclosure, the technology that digitally signs the validity of the transmitted content, including challenge data, with a private key and then verifies its validity using a public key, can be applied to authentication between an image forming apparatus and consumables. [Brief explanation of the drawing]

[0020] [Figure 1] This is a block diagram showing an example of the control configuration of a print authentication system according to the first embodiment. [Figure 2] This diagram illustrates the flow of various information between the IC chip and the printer during the authentication process. [Figure 3] This is a sequence diagram illustrating an example of the processing flow performed by each device during the authentication process. [Figure 4] This sequence diagram illustrates an example of the processing flow performed by each device during the reverse authentication process using a dummy digital signature. [Figure 5] This is a block diagram showing an example of the control configuration of the print authentication system according to the second embodiment. [Figure 6] This is a diagram illustrating the flow of various information between the IC chip and the printer during authentication processing. [Figure 7] This is a sequence diagram showing an example of the flow of processing executed by each device during authentication processing. DETAILED DESCRIPTION OF EMBODIMENTS

[0021] First Embodiment A first embodiment of the present disclosure will be described with reference to the drawings. The present embodiment relates to a print authentication system in which a toner cartridge that is detachably replaceable in a printer is used as a consumable, highly confidential data is recorded on an IC chip provided in the toner cartridge, and the printer authenticates whether or not the data can be accessed.

[0022] Overall Configuration of Print Authentication System FIG. 1 shows an example of the overall configuration of a print authentication system 1 according to the first embodiment. As shown in FIG. 1, the print authentication system 1 includes a printer 100 and a toner cartridge 200. The toner cartridge 200 is mechanically attachable to and detachable from the printer 300, and when mounted, the printer 300 performs printing using the toner of the toner cartridge 200. The toner cartridge 200 also has an IC chip 210, and when mounted on the printer 100, the IC chip 210 is electrically connected to an IC interface 190 to enable information transmission and reception. The printer 100 is an example of an image forming apparatus, and the toner cartridge 200 is an example of a consumable.

[0023] Printer The printer 100 includes a control unit 110, a main body storage unit 120, a printing unit 130, a display unit 140, an operation unit 150, a communication unit 160, a USB interface 170, a cartridge holder 180, an IC interface 190, and the like. The control unit 110, the main body storage unit 120, the printing unit 130, the display unit 140, the operation unit 150, the communication unit 160, the USB interface 170, and the IC interface 190 are connected to be capable of transmitting and receiving information via a bus 105.

[0024] The main storage unit 120 stores various programs 121, various printer data 122, and a secret key 123, which will be described later. The various programs 121 include, for example, a program that executes the control contents of the printer 100 according to the sequence diagrams shown in Figures 3 and 4, which will be described later. The various printer data 122 include, for example, the cumulative number of printed pages used, which is counted up when printing is performed by a print job, and the image data to be printed.

[0025] The control unit 110 is a data processing device, such as a processor like a CPU. The control unit 110 executes various programs stored in the main storage unit 120. The printing unit 130 transports printing paper by a transport mechanism (not shown) and prints images onto the paper, for example, using an electrophotographic method. The display unit 140 is, for example, a liquid crystal display, capable of displaying various information. The operation unit 150 is, for example, a keyboard or buttons, and accepts user input. The user can input various instructions to the printer 100 by operating the operation unit 150.

[0026] In this example, the communication unit 160 communicates information with servers and other information devices (not shown) via a wide-area communication network NT such as the Internet or a wireless communication antenna ANT such as an NFC antenna. The USB interface 170 communicates information with other devices via a cable connection compliant with the USB standard.

[0027] The cartridge holder 180 houses the toner cartridge 200 and is mechanically connectable to it. The printing unit 130 uses the toner supplied from the toner cartridge 200 to perform printing. The IC interface 190 is provided in the cartridge holder 180 and, when the toner cartridge 200 is installed, is electrically connected to the IC chip 210 (described later) to enable information transmission and reception.

[0028] <Toner Cartridge> As described above, the toner cartridge 200 has a housing for containing toner and an IC chip 210 capable of sending and receiving information. The IC chip 210 has a memory control unit 220 and a non-volatile storage device 230.

[0029] The memory control unit 220 primarily functions as a memory controller for the non-volatile storage device 230, but by executing various programs 231 described later, it can also send and receive information via the IC interface 190 and perform various data processing tasks.

[0030] The non-volatile memory device 230 stores various programs 231, various cartridge data 232, and a public key 233, which will be described later. The various programs 231 include, for example, a program that executes the control contents of the IC chip 210 according to the sequence diagrams shown in Figures 3 and 4, which will be described later. The various cartridge data 122 include, for example, information such as the model number, destination information, individual identification information, and toner level of the toner cartridge for the toner cartridge 200. Note that the IC chip 210 is an example of an IC chip.

[0031] <Regarding access authentication for cartridge data and its specific methods> The contents of the cartridge data 232 stored in the non-volatile memory device 230 of the IC chip 210 are important information for the proper use of the toner cartridge 200. Therefore, authentication processing is required from a security standpoint for the cartridge data 232.

[0032] In contrast, the print authentication system 1 of this embodiment performs an authentication process to verify whether the printer 100 or the other device requesting access to the cartridge data 232 is a legitimate device when access to the cartridge data 232 is requested from an external source. In other words, in this authentication process, the IC chip 210 that holds the cartridge data 232 acts as the certifying side, and the external device requesting access to the cartridge data 232 acts as the authenticated side, and its legitimacy is determined. The specific method of the authentication process in this embodiment is a combination of two methods, as shown in Figure 2: a challenge-response method and a digital signature method.

[0033] In a typical digital signature scheme (though not specifically illustrated), the sender, who possesses the original data to be sent or received, calculates a hash value for that data using a predetermined hash function. This hash value is then encrypted with a private key to create the signature data, which is attached to the original data and sent to the receiver. The receiver decrypts the received signature data using a public key and compares the resulting hash value with the hash value calculated from the received original data using the same hash function as the sender. If they match, the receiver can confirm that the data has not been tampered with.

[0034] In a typical challenge-response method, for example, when using a password for authentication (though not specifically illustrated), the party being authenticated sends an authentication request to the certifying party. The certifying party generates challenge data in response to the authentication request and sends it to the party being authenticated. The party being authenticated returns a hash value calculated using a predetermined hash function on the received challenge data and password as response data. The certifying party then compares the original challenge data with the response data calculated using the same hash function on a password that the certifying party has stored beforehand, and if they match, authentication is considered successful. In other words, in a challenge-response method, the legitimacy of the party being authenticated is confirmed without exchanging the password itself.

[0035] In this embodiment, the authentication side generates and sends challenge data, and the authenticated side returns the generated response data and a digital signature encrypted with the private key 123 in response to the received challenge data. Upon receiving this, the authentication side confirms the legitimacy of the authenticated side through a double verification process: verification of the digital signature and verification of the response data.

[0036] Specifically, as shown in Figure 2, the printer 100 on the authentication side, which initially requests the cartridge data 232, requests the IC chip 210 on the authentication side, which holds the cartridge data 232, to start the authentication process. In response, the memory control unit 220 of the IC chip 210 generates a nonce value as challenge data, for example, using a random number, and sends it back to the printer 100. The control unit 110 of the printer 100 generates validation data as a hash value using a hash function that it has stored in advance for the received challenge data. The control unit 110 also encrypts this validation data using a secret key 123 that it has stored in advance to create a digital signature, and sends this validation data and digital signature together back to the IC chip 210.

[0037] The memory control unit 220 of the IC chip 210 verifies the validity of the digital signature by checking whether the validity data obtained by decrypting the received digital signature with the public key 233 matches the validity data as received. Subsequently, it calculates the validity data itself using a hash function that it has previously stored on the challenge data it has generated, and verifies the validity of the validity data by checking whether this matches the validity data as received. If it is determined that the data generated by the memory control unit 220 of the IC chip 210 and the data received from the control unit 110 of the printer 100 match in terms of both the validity data and the digital signature, the authentication process of the printer 100 being authenticated is successful, and the lock on data access is released.

[0038] As described above, this embodiment enables a dual authentication process combining a challenge-response method and a digital signature method. That is, the legitimacy of the authenticated party can only be authenticated if the authenticated party stores a private key 123 corresponding to the public key 233 stored by the authenticater, and if both the authenticater and the authenticated party know the same hash function. Furthermore, since this authentication process itself does not require the authentication party to send or receive the confidential data itself, the security of the data can be improved.

[0039] <Control Procedure> Figure 3 shows an example of the processing flow performed by each device in the print authentication system 1 during the authentication process. In the following description, each device will be described as performing the processing performed by the control unit of each device. It is assumed that the same hash function, the corresponding public key 233, and the private key 123 are pre-stored in both the main storage unit 120 of the printer 100 and the non-volatile storage device 230 of the IC chip 210, respectively.

[0040] As shown in Figure 3, in step S5, the printer 100 sends a request to the IC chip 210 to start the authentication process. Upon receiving this, the IC chip 210 generates challenge data in step S10 and sends it to the printer 100 in step S15.

[0041] Upon receiving this, the printer 100 generates validation data as a hash value using a hash function on the challenge data in step S20. Next, in step S25, it encrypts the validation data with the secret key 123 to generate a digital signature, and in step S30, it sends the validation data and digital signature together back to the IC chip 210.

[0042] Upon receiving these, the IC chip 210 verifies the validity of the digital signature in step S35. Specifically, if the validity data obtained by decrypting the received digital signature with the public key 233 matches the validity data as received, the digital signature is determined to be valid. Conversely, if the validity data obtained by decrypting the received digital signature with the public key 233 does not match the validity data as received, the digital signature is determined to be invalid. If the digital signature is determined to be invalid (S35: NO), error handling is performed in step S40. On the other hand, if the digital signature is determined to be valid (S35: YES), the process proceeds to step S45.

[0043] In step S45, the validity of the activation data is verified. Specifically, the system calculates the activation data itself using a hash function on the challenge data generated in step S10, and determines that the activation data is valid if this matches the received activation data. Conversely, if the activation data calculated by the system does not match the received activation data, it determines that the activation data is not valid. If the activation data is determined to be not valid (S45: NO), error processing is performed in step S40. On the other hand, if the activation data is determined to be valid (S45: YES), the system proceeds to step S50.

[0044] In step S50, the IC chip 210 releases the access lock to the cartridge data 232 of the non-volatile storage device 230, and in step S55, it notifies the printer 100 that the access lock has been released.

[0045] In the above, step S5 is an example of the first transmission process, and the authentication process start request is an example of the first authentication request. Also, step S15 is an example of the second transmission process and data transmission process, and the challenge data is an example of the first challenge data. Also, the activation data generated in step S20 is an example of the first activation data, the digital signature generated in step S25 is an example of the first digital signature, and the private key 123 used at this time is an example of the first private key, and step S30 is an example of the third transmission process and retrieval process. Also, step S35 is an example of the first verification process and verification process, and the public key 233 used at this time is an example of the first public key. Also, step S45 is an example of the first access determination process and access determination process.

[0046] <Effects of the First Embodiment> In this embodiment, the print authentication system 1 uses a toner cartridge 200 to authenticate the printer 100. First, in step S5, the control unit 110 of the printer 100 sends an authentication process start request to the IC chip 210. In response to this authentication process start request, the IC chip 210 generates challenge data and sends it to the control unit 110.

[0047] The control unit 110 generates activation data based on the challenge data and generates a digital signature using the private key 123, which has been previously associated with the public key 233, in the activation data. The generated activation data and digital signature are transmitted to the IC chip 210 in step S30.

[0048] In step S35, the IC chip 210 verifies the validity of the transmitted digital signature using the public key 233 associated with the private key 123. Furthermore, in step S45, the IC chip 210 determines whether or not to allow access to the data stored in the IC chip 210 based on the verification result. As a result, if a correct digital signature is made using the private key 123, the data in the IC chip 210 can be accessed; if a correct digital signature is not made, the data in the IC chip 210 cannot be accessed.

[0049] As explained above, according to this disclosure, the technology for verifying the validity of content that has been digitally signed with a private key 123 and transmitted, including challenge data, using a public key 233, can be applied to authentication between a printer 100 and a toner cartridge 200.

[0050] Furthermore, in addition to using the same single private key 123 fixedly for use by the printer 200, it is also permissible to rewrite or add to the private key 123 later, provided that its confidentiality is guaranteed.

[0051] For example, the control unit 110 of the printer 100 executes a secret key acquisition process to obtain a secret key 123 from an external server or device of the printer 100 via short-range wireless communication via an NFC antenna ANT or the like, or via wired communication via a communication network NT or the like (not shown). Then, in step S30, a digital signature generated using the secret key 123 obtained in the secret key acquisition process as validating data may be sent to the IC chip 210. This eliminates the need to pre-install the secret key 123 in the printer 100, making it possible to rewrite or add the secret key 123 later.

[0052] In addition, multiple types of secret keys 123 may be stored in the main storage unit 120 depending on the version information of the IC chip 210. In this case, the control unit 110 sends a digital signature generated using one of the multiple types of secret keys 123 that matches the version information read from the IC chip 210 as the activation data to the IC chip 210 in step S30.

[0053] Thus, the secret key 123 may be divided into multiple types depending on the version information of the IC chip 210. This ensures that even if the secret key 123 of an IC chip 210 provided during a certain version period is leaked, the secret keys 123 related to other versions are protected, thus ensuring security. The main storage unit 120 is an example of the main memory.

[0054] In addition, multiple types of secret keys 123 may be provided depending on the multiple storage areas of the IC chip 210. In this case, the control unit 110 sends a digital signature generated using at least one secret key 123 that matches the storage area to be accessed from among the multiple types of secret keys 123 as activation data to the IC chip 210 in step S30. By separating the secret keys 123 according to the areas of the IC chip 210 in this way, it is possible to ensure greater security compared to using a single secret key 123 common to all areas.

[0055] Furthermore, in the above embodiment, the control unit 110 of the printer 100 generated activation data as a hash value using a hash function stored in the main unit storage unit 120 for the received challenge data, but the method of generating activation data is not limited to this. For example, the activation data may be a combination of the challenge data and the password. That is, the control unit 110 of the printer 100 may generate activation data based on the password entered by the user and the received challenge data. In that case, the password is also stored in the IC chip 210 in advance, and the activation data is generated similarly by the memory control unit 220, making it possible to verify the activation data.

[0056] Furthermore, in the above embodiment, a legitimate toner cartridge 200 holds highly confidential data, and an authentication process is performed to verify its legitimacy for external devices requesting access to it. However, it is conceivable that a toner cartridge 200 may appear that allows access to the IC chip 210 for any digital signature based on any secret key 123. In response to this, the printer 100 may perform a second authentication process to verify the legitimacy of the IC chip 210 of the toner cartridge 200.

[0057] Specifically, the second authentication process involves executing the procedure shown in the sequence diagram of Figure 4, which is a modified and partially abbreviated version of Figure 3. In other words, the printer 100 generates a dummy digital signature in step S25A using an incorrect dummy private key that does not correspond to the original public key 233, and sends it to the IC chip 210 in step S30A. In this case, if the IC chip 210 performs verification correctly, the validity of the digital signature will be denied, as in the verification process of step S35, and access to the data will not be permitted, as in the access determination process of step S40. On the other hand, if the IC chip 210A allows access to the IC chip 210 for any digital signature based on any private key 123, as described above, the validity of the digital signature will always be unconditionally affirmed, as in the verification process of step S35A shown in the diagram, and the access lock to the data will always be unconditionally released, as in the access determination process of step S40A.

[0058] Based on the above, the printer 100 verifies the validity of the IC chip 210 by the determination in step S60. That is, as shown in the diagram, if a dummy digital signature is sent to the IC chip 210A in step S30A, but an access lock release notification is returned in step S55, the validity of the IC chip 210A is denied in step S60. In other words, if an access lock release notification is received (S60: YES), the validity of the IC chip 210A is denied, and error processing is performed in step S65. On the other hand, if an access lock release notification is not received in step S55 (S60: NO), the validity of the IC chip 210 is affirmed in step S70, and that is, the second authentication is considered successful.

[0059] As a result of the above, legitimacy can be determined by whether or not access to the IC chip 210 is permitted based on the digital signature using the dummy private key. It is effective to perform this second authentication process multiple times in a random order, alternating between using the dummy private key and the legitimate private key 123. The dummy digital signature described above is an example of a second digital signature, and step S30A is an example of a fourth transmission process.

[0060] <Second Embodiment> A second embodiment of this disclosure will be described with reference to the drawings. This embodiment relates to a print authentication system in which a toner cartridge, which is attached to and replaced in a printer, is a consumable item, highly confidential data is recorded in the printer, and an IC chip authenticates whether or not it can access that data.

[0061] Figure 5 shows an example of the overall configuration of the print authentication system 1A according to the second embodiment. The difference between the configuration of this second embodiment and the first embodiment is that, as shown in Figure 5, the secret key 234 is stored in the IC chip 210 and the public key 124 is stored in the printer 100. In addition, the printer data 122 stored in the main storage unit 120 of the printer 100 is highly confidential data to be accessed. The other configurations are the same as those of the first embodiment and will not be explained here.

[0062] In other words, in the authentication process of this embodiment, the printer 100, which holds the printer data 122, acts as the authentication side, and the IC chip 210, which requests access to the printer data 122, acts as the authentication side, determining its legitimacy. In this embodiment as well, as shown in Figure 6, an authentication process combining a challenge-response method and a digital signature method is performed. In other words, the printer 100 acts as the authentication side, and the IC chip 210, which requests access, acts as the authentication side, thus reversing the roles, but the individual processing contents themselves are the same as in the first embodiment described above.

[0063] Therefore, the authentication process performed in this embodiment is as shown in Figure 7, and each step is performed symmetrically compared to the first embodiment described above.

[0064] In step S105, the IC chip 210 sends a request to the printer 100 to start the authentication process. Upon receiving this, the printer 100 generates challenge data in step S110 and sends it to the IC chip 210 in step S115.

[0065] Upon receiving this, the IC chip 210 generates validation data as a hash value using a hash function on the challenge data in step S120. Next, in step S125, it encrypts the validation data with the secret key 234 to generate a digital signature, and in step S130, it sends the validation data and digital signature together back to the printer 100.

[0066] Upon receiving these, the printer 100 verifies the validity of the digital signature in step S135. Specifically, the digital signature is considered valid if the validity data obtained by decrypting the received digital signature with the public key 124 matches the validity data as received. If the digital signature is verified to be invalid (S135: NO), error handling is performed in step S140. On the other hand, if the digital signature is verified to be valid (S135: YES), the process proceeds to step S145.

[0067] In step S145, the validity of the activation data is verified. Specifically, the system calculates the activation data itself using a hash function on the challenge data generated in step S110, and if this matches the received activation data, the activation data is considered valid. If the activation data is verified to be invalid (S145: NO), error processing is performed in step S140. On the other hand, if the activation data is verified to be valid (S145: YES), the system proceeds to step S150.

[0068] In step S150, the printer 100 releases the access lock to the printer data 122 in the main unit storage unit 120, and in step S155, it notifies the IC chip 210 that the access lock has been released.

[0069] In the above, step S105 is an example of the fifth transmission process, and the authentication process start request is an example of the second authentication request. Also, step S115 is an example of the sixth transmission process, and the challenge data is an example of the second challenge data. Furthermore, the activation data generated in step S120 is an example of the second activation data, the digital signature generated in step S125 is an example of the second digital signature, and the private key 234 used at this time is an example of the second private key, and step S130 is an example of the seventh transmission process. Furthermore, step S135 is an example of the second verification process, and the public key 124 used at this time is an example of the second public key. Furthermore, step S145 is an example of the second access determination process.

[0070] <Effects of the second embodiment> In this embodiment, the print authentication system 1A allows the printer 100 to authenticate the toner cartridge 200. First, in step S105, the IC chip 210 sends an authentication process start request to the control unit 110 of the printer 100. In response to this authentication process request, the control unit 110 generates challenge data and sends it to the IC chip 210.

[0071] The IC chip 210 generates activation data based on the challenge data and generates a digital signature using the private key 234, which has been previously associated with the public key 124, in the activation data. The generated activation data and digital signature are transmitted to the control unit 110 in step S130.

[0072] In step S135, the control unit 110 verifies the validity of the transmitted digital signature using the public key 124 associated with the private key 234. Furthermore, in step S145, the control unit 110 determines whether or not to allow access to the printer 100 based on the verification result. As a result, if a correct digital signature is made using the private key 234, access to the printer 100 is permitted; if a correct digital signature is not made, access to the printer 100 is denied.

[0073] As described above, according to this embodiment, the technology of verifying the validity of the content transmitted after digitally signing the activation data, including the challenge data, with the private key 234 using the public key 124 can be applied to authentication between the printer 100 and the toner cartridge 200.

[0074] In this embodiment, the public key 124 used by the printer 200 may be obtained and added from an external server or device through a public key acquisition process via short-range wireless communication via an NFC antenna ANT or wired communication via a communication network NT (not shown). Then, in step S135, the validity of the digital signature is verified using the public key 124 obtained in the public key acquisition process. As a result, there is no need to pre-install the public key 124 on the printer 100 side, and it becomes possible to rewrite or add the public key 124 later.

[0075] In addition, multiple types of secret keys 234 may be stored in the non-volatile storage device 230, depending on the firmware version of the printer 100. In this case, the memory control unit 220 sends a digital signature generated using one of the multiple types of secret keys 234 that matches the firmware version of the printer 100 as the activation data to the control unit 110 of the printer 100 in step S130.

[0076] In this way, the private key 234 is separated according to the firmware version of the printer 100. This ensures that even if the private key 234 for the firmware of printer 100 provided at a certain time is leaked, the private keys 234 for other versions are protected, thus maintaining security.

[0077] Additionally, multiple types of secret keys 234 may be provided, corresponding to the multiple storage areas in the printer 100's main storage unit 120. Furthermore, the IC chip 210 may authenticate the printer 100.

[0078] Furthermore, while the above describes the IC chip 210 actively sending a request to the printer 100 to start the authentication process in step S105, this is not the only option. For example, the IC chip 210 itself may not perform autonomous control, but rather be a device that passively responds to commands from the printer 100. In that case, the printer 100 requests the start of the authentication process. That is, step S105 may be omitted, and the printer 100 may first generate challenge data in step S110, and together with this, send a request to start the authentication process from the printer 100 to the IC chip 210 in step S115.

[0079] Furthermore, the sequence diagrams shown in Figures 3, 4, and 7 do not limit this disclosure to the procedures shown in the sequence diagrams, and procedures may be added, deleted, or their order changed within the scope that does not deviate from the spirit and technical concept of this disclosure.

[0080] In addition to what has already been described above, the methods described in the above embodiments and their respective modifications may be used in appropriate combinations.

[0081] Furthermore, although not to list them individually, this disclosure will be implemented with various modifications, within the scope that does not deviate from its intent. [Explanation of symbols]

[0082] 1.1A Print Authentication System 100 Printers (an example of an image forming apparatus) 110 Control Unit 120 Main unit storage (main unit memory) 123 Private Key (An example of a first private key) 124 Public Key (An example of a second public key) 200 Toner Cartridges (Example of a consumable item) 210 IC chips 233 Public Key (Example of a First Public Key) 234 Private Key (An example of a second private key)

Claims

1. Control unit and The main memory stores the first private key, The consumable has an IC chip that stores a first public key corresponding to the first private key, An image forming apparatus comprising, The control unit, First transmission process that transmits the first authentication request to the IC chip Execute, The aforementioned IC chip is A second transmission process generates first challenge data and transmits it to the control unit in response to the transmission of the first authentication request by the first transmission process. Execute, The control unit, A third transmission process is performed to generate first activation data based on the first challenge data transmitted by the second transmission process, generate a first digital signature using the first secret key on the first activation data, and transmit the first activation data and the first digital signature to the IC chip. The aforementioned IC chip is A first verification process that decrypts the first digital signature received from the control unit by the third transmission process using the first public key, and determines whether the decrypted data obtained from the decryption matches the first activation data received from the control unit, A first access determination process determines whether to allow access to the data stored in the IC chip according to the result of the first confirmation process, Execute An image forming apparatus characterized by the following:

2. The control unit further, A secret key acquisition process that acquires the first secret key from outside the image forming apparatus via short-range wireless communication or wired communication. Execute, In the third transmission process, the first digital signature generated using the first secret key obtained in the secret key acquisition process as the first activation data is transmitted to the IC chip. The image forming apparatus according to claim 1, characterized in that it is a feature of the present invention.

3. The aforementioned main memory is Multiple types of the first secret key are stored according to the version information of the IC chip. The control unit, From the IC chip, read the version information of the IC chip. In the third transmission process, the first digital signature generated using one of the multiple types of first secret keys that conforms to the version in the first activation data is transmitted to the IC chip. The image forming apparatus according to claim 1, characterized in that it is a feature of the present invention.

4. The first private key is, Multiple types are available depending on the multiple memory areas of the IC chip. The control unit, In the third transmission process, the first digital signature generated using at least one of the multiple types of first secret keys that is compatible with the storage area to be accessed as the first activation data is transmitted to the IC chip. The image forming apparatus according to claim 1, characterized in that it is a feature of the present invention.

5. The control unit further, A fourth transmission process is performed to generate a second digital signature using a dummy private key that does not correspond to the first public key on the first activation data based on the first challenge data transmitted by the second transmission process, and to transmit the first activation data and the second digital signature to the IC chip. If access is permitted from the aforementioned IC chip, error handling is executed. The image forming apparatus according to claim 1, characterized in that it is a feature of the present invention.

6. The aforementioned main memory further stores a hash function, The activation data is the hash value obtained by calculating the challenge data using a hash function. The image forming apparatus according to feature 1.

7. The activation data further includes a password The image forming apparatus according to feature 1.

8. The IC chip includes a memory control unit and a non-volatile memory device for storing the secret key. The image forming apparatus according to feature 1.

9. An image forming apparatus having a control unit, A consumable part that can be attached to the image forming apparatus, the consumable part having an IC chip, A print authentication system comprising: The control unit, A sixth transmission process that generates second challenge data and sends it to the IC chip as a second authentication request. Execute, The aforementioned IC chip is A seventh transmission process is executed which generates second activation data based on the second challenge data transmitted by the sixth transmission process, generates a second digital signature using the second secret key on the second activation data, and transmits the second activation data and the second digital signature to the control unit. The control unit, A second verification process that uses a second public key corresponding to the second private key to verify the validity of the second digital signature transmitted by the seventh transmission process, A second access determination process determines whether or not to permit access to the image forming apparatus, based on the results of the validation process performed in the second verification process, Execute A print authentication system characterized by the following features.

10. The control unit further, Public key acquisition process to acquire the second public key via short-range wireless communication or wired communication. Execute, In the second verification process, the validity of the second digital signature is verified using the second public key obtained in the public key acquisition process. The print authentication system according to claim 9, characterized in that it is as described above.

11. The aforementioned second private key is, Multiple types are available depending on the production date of the image forming apparatus or the firmware version of the image forming apparatus. The aforementioned IC chip is In the seventh transmission process, the second digital signature generated using one of the multiple types of second private keys that matches the production period or version in the second activation data is transmitted to the control unit. The print authentication system according to claim 9, characterized in that way.

12. A consumable item configured to be detachably attached to an image forming apparatus, comprising an IC chip and a memory control unit that controls the input and output of information to the IC chip, The memory control unit, A data transmission process that generates challenge data and transmits it to the image forming apparatus in response to an authentication request transmitted from the image forming apparatus, In the image forming apparatus, an acquisition process is performed to receive and acquire valid data generated based on the challenge data transmitted by the data transmission process and a digital signature generated using a secret key on the valid data from the image forming apparatus. A verification process that uses the public key corresponding to the private key to verify the validity of the digital signature obtained through the acquisition process, An access determination process determines whether or not to permit access to the data stored in the IC chip, based on the results of the validation process performed above. Execute A consumable product characterized by the following features.

13. A consumable item that can be attached to and detached from an image forming apparatus having a control unit, and a method for printing authentication of the consumable item having an IC chip, A first transmission step in which the control unit transmits a first authentication request to the IC chip, The IC chip generates first challenge data in response to the transmission of the first authentication request and transmits it to the control unit in a second transmission step, The control unit generates first activation data based on the first challenge data, generates a first digital signature using the first secret key on the first activation data, and transmits the first activation data and the first digital signature to the IC chip in a third transmission step. The IC chip performs a first verification step in which the validity of the first digital signature is verified using the first public key corresponding to the first private key, A first access determination step determines whether or not to allow access to the data stored in the IC chip, based on the results of the validation check performed in the first verification step, has A printing authentication method characterized by the following features.

14. A consumable item that can be attached to and detached from an image forming apparatus having a control unit, and a method for printing authentication of the consumable item having an IC chip, A fifth transmission step in which the IC chip transmits a second authentication request to the control unit, The control unit performs a sixth transmission step in which, in response to the transmission of the second authentication request, it generates second challenge data and transmits it to the IC chip, A seventh transmission step in which the IC chip generates second activation data based on the second challenge data, generates a second digital signature using the second secret key on the second activation data, and transmits the second activation data and the second digital signature to the control unit, The control unit performs a second verification step in which it verifies the validity of the second digital signature using the second public key corresponding to the second private key, A second access determination step determines whether or not to permit access to the image forming apparatus, based on the results of the validation check performed in the second verification step, has A printing authentication method characterized by the following features.

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