JP6277846B2 - COMMUNICATION DEVICE, COMMUNICATION DEVICE CONTROL METHOD, AND PRINTER - Google Patents

Description

  The present invention relates to a technique for performing authentication using a digital certificate between a server and a client when connecting to a network. In particular, the present invention relates to a communication device that performs authentication using an electronic certificate, a printer, and a control method thereof.

  In a device (client) that transmits and receives data via a network, a method of ensuring security by performing authentication using an electronic certificate with an authentication server when connecting to the network. For example, in the authentication using the EAP-TLS authentication protocol, when the client connects to the network, the client performs server authentication for examining the authentication server. In server authentication, a client examines a server certificate that is an electronic certificate of an authentication server. The server certificate includes information such as the signature information from the certificate authority and the validity period, and the client examines the contents. When the client successfully authenticates the server certificate and the authentication server succeeds in authenticating the client, a service for connecting to the network is started. The server certificate is supplied to the client in advance by some means.

  In server authentication, as one of verification items, time verification is performed in which the client examines whether or not the server certificate is within the valid period. In the time verification, the consistency between the validity period included in the server certificate and the time information (current time) held by the client is verified. Specifically, it is verified whether or not the current time is within the valid period of the server certificate. As the time information held by the client, when the client has a built-in clock, the time information indicated by the built-in clock can be used. However, if the internal clock of the client stops when the power is turned off, the time of the internal clock when the client is restarted may be different from the correct current time. Therefore, time verification cannot be performed accurately, and a server certificate that has passed the validity period may be erroneously determined to be within the validity period. Also, if the client's built-in clock is messed up, a server certificate with a valid period that is impossible (for example, a server certificate with a future period that should not have been issued) is mistakenly valid. There is a risk of judging.

  As described above, when the built-in clock does not move correctly or the device without the built-in clock is a client, it is not possible to perform the correct time verification only with the information held by itself. Therefore, it is necessary for the client to acquire the correct current time by some means. As a source of the correct current time, there is an NTP server that exists on the network. However, a client that cannot connect to the network unless the server authentication is successful cannot obtain the current time from the NTP server. Therefore, in Patent Document 1, if the client does not have the correct current time information, the client performs temporary authentication to check the reliability of other information without performing time verification, and if the temporary authentication is successful, the client connects to the network. Get accurate time information from a time server on the network. Then, the authenticity of the server certificate is checked by performing the main authentication including the time verification using the acquired time information.

JP 2010-193158 A

  In the authentication method of Patent Literature 1, it is possible to acquire the correct current time via a network and perform time verification based on this time. Therefore, the validity period of the server certificate can be accurately verified even when the built-in clock is not provided or the time of the built-in clock is not correct, and security when connecting to the network can be ensured. However, in the method of Patent Document 1, the client is connected to the network without verifying the validity period of the server certificate. Therefore, even if the client receives a server certificate that has expired, the client is connected to the network, and there is a problem that security cannot be ensured. Moreover, since it connects to a network in order to detect the expiration date, there is a problem that wasteful processing is performed and efficiency is poor.

  As a method for verifying the correct time other than the two-step authentication as in Patent Document 1, the network administrator notifies the user of the client connected to the network of the time within the validity period of the server certificate in advance. There is a method to set the time manually. If the notified time is stored in the client, the time verification will not fail until the server certificate is updated, so only the main authentication is required. However, with such a method, each time a server certificate is updated, the user must manually update the time setting for all of the many clients that use the same server certificate. Therefore, there is a problem that the burden on the user is large and the operation cost increases.

  In view of these points, the problem of the present invention is to efficiently and accurately authenticate a server certificate by a client (communication device) that may have incorrect time information, and to increase operational costs. It is to ensure security when connecting to the network.

  In order to solve the above-described problem, the present invention provides a method for controlling a communication apparatus that performs server authentication for examining a server certificate that is an electronic certificate with a valid period set when connected to a network. In server authentication, it is determined whether the time indicated by the time information held by the communication device is before the start of the valid period, within the valid period, or after the end of the valid period The server certificate is used when the time indicated by the time information is later than the end of the valid period as a result of the determination in the first authentication step. Executing the step of canceling the connection to the network, and if the time indicated by the time information is within the valid period, other authentication information included in the server certificate It performs a second authentication step of judging, when showing the time information is, in the case was before the beginning of the validity period, and executes a step of performing a process set in advance.

  In addition, the communication device of the present invention includes a time management unit that holds time information, an authentication unit that performs server authentication for examining a server certificate that is an electronic certificate with a valid period when connected to a network, The authentication unit includes a time point indicated by the time information held by the time management unit in the server authentication, before the start time of the effective period, within the effective period, and at the end of the effective period. When the first authentication is performed to determine whether the time is later than the time, and when the time indicated by the time information is later than the end of the valid period as a result of the determination of the first authentication If the connection to the network using the server certificate is stopped and the time indicated by the time information is within the valid period, other authentication information included in the server certificate is stored. Review 2 performs authentication, time when the time information is indicated in the case was before the beginning of the validity period, and performs the process set in advance.

  As described above, in the server authentication which is a connection condition to the network, the present invention performs the comparison determination between the time point indicated by the time information held by the communication device and the validity period of the server certificate, and performs the optimum processing according to the comparison determination result. I do. That is, when the time information of the communication device is after the valid period and is clearly expired, the connection to the network using the server certificate is abandoned at that point and no unnecessary processing is performed. In addition, when the correct time information and a valid server certificate are provided, time verification (first authentication) is surely successful. And if the time information is earlier than the valid period, if the time information is old for some reason, it may actually be within the valid period. Can try. In this way, the consistency between the time information held by the communication device and the validity period of the server certificate can be examined more appropriately and efficiently than before. Therefore, it is possible to achieve both security at the time of network connection and efficient establishment of the network connection. Further, it is possible to avoid an increase in operation cost without increasing the load on the user.

  In the communication apparatus and the control method thereof according to the present invention, the preset process is a provisional setting process in which the time information is provisionally set to information indicating a preset time point within the range of the valid period. It is desirable to execute the first authentication step again after performing the above. In this case, when there is a possibility that the server certificate is valid, it is possible to attempt to connect to the network by succeeding time verification (first authentication) for the time being. Therefore, you can avoid the inconvenience of not having an internal clock even if you have a valid server certificate, or being unable to connect to the network because the internal clock has stopped for some reason. An increase can also be avoided.

  In the communication device and the control method thereof according to the present invention, when the information indicating the current time is received without going through the network, the time information is updated to the received current time, and the updated time information is updated. Preferably, the first authentication step is performed. As described above, when correct time information can be acquired except for network connection, time verification (first authentication) can be performed more accurately by updating the time information. As a method of acquiring time information other than the network connection, various radio wave information including time information, for example, GPS information, beacons, radio wave information for radio clocks, radio wave information supplied from mobile phone base stations, digital TV And radio wave information of FM multiplex broadcasting. In addition, when time information can be acquired from a device in the local area network, the information may be used.

  In the communication apparatus and the control method thereof according to the present invention, when connection to the network using the server certificate becomes possible, the time information is updated to the current time acquired via the network. It is desirable to execute time update processing (time update step). In this way, the correct time information acquired from the time server (NTP server) on the network can be held in the communication device. Therefore, in the subsequent server authentication, it is possible to correctly verify the consistency between the time information possessed by the communication apparatus and the validity period of the server certificate.

  In this case, in the communication device and the control method thereof according to the present invention, in the time update process (time update step), on the condition that the time difference between the time information and the current time is equal to or greater than a preset threshold value, It is desirable to update the information. If it does in this way, it can avoid updating time information unnecessarily frequently. In addition, time update is not performed at the time lag due to the required time when connecting to a time server on the network and acquiring current information, so that the time update process is not repeated due to such time lag. it can.

  Next, a printer according to the present invention includes the above-described communication device and a printing unit that prints data received via the communication device on a print medium.

  According to the present invention, in server authentication, which is a connection condition to the network, a comparison determination is performed between the time point indicated by the time information held by the communication device and the validity period of the server certificate, and an optimum process is performed based on the comparison determination result. . Accordingly, the consistency between the time information held by the communication device and the validity period of the server certificate can be examined more appropriately and efficiently than before. Therefore, it is possible to achieve both security at the time of network connection and efficient establishment of the network connection. Further, the user's load does not increase, and an increase in operation cost can be avoided.

1 is a configuration diagram of a printing system including a printer including a communication device according to an embodiment of the present invention. It is explanatory drawing of a server certificate. It is a block diagram which shows the principal part of a communication part. It is a flowchart of server authentication. It is explanatory drawing of time verification.

(Printing system)
FIG. 1 is a configuration diagram of a printing system including a printer including a communication device according to an embodiment of the present invention. The printer 1 is a portable mobile printer, and includes a communication unit 11 (communication device), a printing unit 12 that prints data received from the communication unit 11 on a print medium, and a control unit that controls the communication unit 11 and the printing unit 12. 13 is provided. The printing unit 12 includes a print head and a transport mechanism that transports the print medium via a print position by the print head. The printer 1 can be connected via a communication unit 11 to a local area network 2 that is a communication network by wired communication or wireless communication. The local area network 2 is a communication network compliant with a standard such as IEEE 802.11, for example, and a plurality of printers 1 can be connected thereto. The printer 1 is not limited to a mobile printer, and may be another printer.

  The printer 1 in the local area network 2 can be connected to an external network 4 (network) via a router 3. The external network 4 is a communication network (so-called Internet) using the Internet protocol (IP). A management server 5, an NTP server 6 and the like are connected to the external network 4. The management server 5 is a server that manages data processed by the printer 1, for example. The NTP server 6 is a server that performs time synchronization of communication devices that can be connected to the external network 4 using the NTP protocol (Network Time Protocol).

  When the printer 1 in the local area network 2 makes a secure connection to the external network 4, first, authentication is performed for establishing encrypted communication. In this embodiment, a communication device having a router function and a server program is used as the router 3, and the function of the authentication server 7 is implemented in the router 3. Alternatively, the router 3 may perform authentication by communicating with an authentication server installed on the local area network 2 or the external network 4. Alternatively, the router 3 and the printer 1 may be connected via an access point. In this case, the access point may have an authentication server function, or may be connectable to a device having the authentication server function.

  As authentication at the time of connection to the external network 4, server authentication in which the printer 1 examines the reliability of the authentication server 7 and mutual authentication in which client authentication in which the authentication server 7 examines the reliability of the printer 1 is performed. As an example of such a mutual authentication method, for example, an EAP-TLS (Extensible Authentication Protocol-Transport Layer Security) authentication protocol is used. In the EAP-TLS authentication protocol, server authentication and client authentication are performed using electronic certificates. In the server authentication, the printer 1 examines a server certificate 8 that is an electronic certificate that proves the reliability of the authentication server 7. In the client authentication, the authentication server 7 examines a client certificate that is an electronic certificate that proves the reliability of the printer 1. Note that server authentication may be performed using an electronic certificate, and client authentication may be performed using a user ID and password. Mutual authentication succeeds when both server authentication and client authentication succeed.

  FIG. 2 is an explanatory diagram of the server certificate 8. The server certificate 8 is an electronic certificate authenticated by a trusted certificate authority, and includes authentication information 81 such as signature information indicating the identity of the authentication server 7. The server certificate 8 has a valid period 82 and includes information on the valid period 82. Further, the server certificate 8 includes information such as a public key used for data encryption. As the effective period 82, for example, a period such as several months or one year is set. The server certificate 8 is installed in the printer 1 from the authentication server 7. Alternatively, the user can manually install the printer 1. A new server certificate 8 is issued before the validity period 82 ends, and is supplied to the printer 1 and its user.

(Communication Department)
FIG. 3 is a block diagram showing the main part of the communication unit 11. The communication unit 11 includes a storage unit 14, a time management unit 15, and an authentication unit 16. The storage unit 14 stores various data including the server certificate 8. The time management unit 15 holds the time information 17 and updates the time information 17. The time information 17 is information that identifies a certain point in time. The authentication unit 16 performs server authentication that is authentication processing on the client side (that is, the communication unit 11 side) in the mutual authentication described above. The communication unit 11 may be in the form of an expansion card such as a network card that can be attached to and detached from the printer 1 or may be incorporated in the printer 1.

  Since the printer 1 does not have an internal clock, the communication unit 11 is provided with a time management unit 15 that holds time information 17 supplied from the outside. For example, the time management unit 15 can set and hold a specific time input by the user in the time information 17. Further, as will be described later, the time management unit 15 acquires the correct current time from the NTP server 6 via the external network 4 and holds the time information when the connection service to the external network 4 is started. A time update process can be performed in which 17 is replaced with the newly acquired current time.

  Here, the time update process by the time management unit 15 is updated only when the time difference between the newly acquired current time and the stored time information 17 is equal to or greater than a preset threshold (for example, 12 hours or more). It is also possible to prevent the time information 17 from being updated when the time difference is less than a preset threshold value. If a time difference such as 12 hours or more is set as the threshold value, the time update process can be prevented from being performed unnecessarily frequently. Therefore, an increase in processing load can be suppressed. In addition, the number of times of writing to a storage medium such as FlashROM is reduced, and the life of the storage medium can be extended. Furthermore, it is possible to avoid a situation in which the time update process is repeatedly performed.

(Server authentication)
FIG. 4 is a flowchart of server authentication. When receiving a connection request to the external network 4 from the control unit 13 of the printer 1, the communication unit 11 activates the authentication unit 16 and starts server authentication. First, the authentication unit 16 reads the server certificate 8 of the authentication server 7 from the storage unit 14 (step S1). In step S1, instead of reading the server certificate 8 stored in advance, a server certificate may be obtained from the authentication server 7 each time a connection request is made. Then, following step S1, first authentication is performed (step S2). The first authentication is verification of whether or not the server certificate 8 is valid in terms of time, and a comparison determination between the validity period 82 of the server certificate 8 and the time information 17 held in the time management unit 15 is performed. Is time verification.

  FIG. 5 is an explanatory diagram of time verification. In FIG. 5, P <b> 1 is the start time of the effective period 82, and P <b> 2 is the end time of the effective period 82. P is the time indicated by the time information 17 held in the time management unit 15. In the first authentication (time verification), the authenticating unit 16 performs a first period T1 that is a period after the end time P2 (that is, after the effective period 82), and from the start time P1 to the end time P2 (that is, Of the three periods, the second period T2 that is within the valid period 82) and the third period T3 that is before the start time point P1 (that is, before the valid period 82). It is determined whether the time point P indicated by the time information 17 is included in the section. FIG. 5 illustrates a case where the time point P indicated by the time information 17 is within the valid period 82.

(1) When the time information is after the valid period (first period T1) In the first authentication, when the time point P indicated by the time information 17 is included in the first period T1 (step S2: P2 <P), the authentication unit 16 Determines that the server certificate 8 has already expired, and ends the server authentication at that time and shifts to a standby state (step S3). That is, since it is clear that mutual authentication fails if the server certificate 8 has expired, the authentication unit 16 stops the connection to the external network 4 using the server certificate 8.

(2) When the time information is within the valid period (second period T2) In the first authentication, when the time point P indicated by the time information 17 is included in the second period T2 (step S2: P1 ≦ P ≦ P2), the authentication The unit 16 determines that the first authentication is successful and proceeds to the second authentication (step S4). That is, when accurate time information and a valid server certificate 8 are held, the first authentication is successful, and the server certificate 8 is determined to be valid at the present time.

  The second authentication is a process for verifying the reliability of the authentication information 81 such as signature information. For example, the authentication information 81 is falsified. If no suspicious point is detected in the authentication information 81, the authentication unit 16 determines that the second authentication is successful. When both the first authentication and the second authentication are successful, the server authentication is successful. Alternatively, the server authentication may be successful if other authentications are further performed and they are also successful. When the second authentication fails (step S4: failure), the authentication unit 16 ends the server authentication and shifts to a standby state (step S3). On the other hand, when the server authentication is successful (step S4: success) and the client authentication performed on the authentication server 7 side is successful, the mutual authentication is successful (step S5). In this case, a connection service with the external network 4 is started for the printer 1 (step S6). Accordingly, the printer 1 can communicate with devices on the external network 4 by encrypted communication via the communication unit 11. Therefore, the printer 1 can receive print data from the management server 5 via the communication unit 11 and perform printing.

  When the connection service to the external network 4 is started, the communication unit 11 connects to the NTP server 6 on the external network 4, acquires accurate current time information from the NTP server 6, and obtains the time information 17. The time update process to synchronize with is performed (step S7). Thereby, when the time information 17 held in the time management unit 15 is deviated from the correct current time, the time deviation is corrected.

(3) When the time information is before the valid period (third period T3) In the first authentication, when the time point P indicated by the time information 17 is included in the third period T3 (step S2: P <P1), time management Although the time information 17 remains old because the time update process of the unit 15 is not properly performed, the server certificate 8 may be within the validity period 82. Therefore, in this case, the authentication unit 16 attempts to make the mutual authentication successful by performing a preset process. Specifically, a temporary setting process for changing the time information 17 by a preset method is performed (step S8). Unlike the time update process, the temporary setting process is a process that can return to the time information 17 before the change. In this embodiment, as the temporary setting process, a process of changing the time information 17 to information indicating a preset time point within the valid period 82 (for example, a start time point P1 of the valid period 82) is performed. Thereafter, the server authentication is reset (step S9). That is, the server authentication being executed is stopped and a new server authentication is started again. As a result, the process returns from step S9 to step S2.

  When server authentication is performed again from the first authentication after the temporary setting process, the first authentication is surely successful because the time information 17 is replaced with information indicating a point in time within the valid period 82. As a result, the second authentication described above is performed (step S4). If this is successful and the client authentication is also successful, the mutual authentication is successful (step S5) and the connection service to the external network 4 is started (step S5). S6). Then, as described above, it connects to the NTP server 6 to acquire accurate current time information and perform time update processing (step S7). As a result, the time information 17 that has been changed by the temporary setting is updated to the correct current time.

  When mutual authentication is successful by the temporary setting process, the connection service to the external network 4 can be limited to the connection to the NTP server 6. In this case, the time update process is not performed immediately after connection to the external network 4, but the time information 17 is temporarily set again at the current time acquired from the NTP server 6 and the server authentication is performed again. In this case, the connection service to the external network 4 is started without being limited to the connection to the NTP server 6, and the time update process is performed. In this way, it can be verified more reliably that the server certificate 8 is valid. Therefore, security can be improved.

(Main effects of this embodiment)
As described above, the communication unit 11 (communication device) included in the printer 1 of this embodiment includes the storage unit 14 that stores the server certificate 8 that is an electronic certificate in which the validity period 82 is set, and holds the time information 17. And a time management unit 15 that performs setting and updating thereof, and an authentication unit 16 that performs server authentication for examining the server certificate 8 when connected to the external network 4. In the server authentication, the authentication unit 16 performs a comparison determination (first authentication / time verification / step S2) between the time point indicated by the time information 17 held by the communication unit 11 and the validity period 82 of the server certificate 8 to perform the comparison determination. The optimum process is performed according to the result. That is, when the time information 17 held by the communication unit 11 is later than the valid period 82 and clearly expires, the connection to the external network 4 using the server certificate 8 is abandoned at that time. Do not perform any processing. Further, when the correct time information 17 and the valid server certificate 8 are provided, the first authentication (time verification) is surely successful. If the time information 17 is before the valid period 82, if the time information 17 is old for some reason, it may actually be within the valid period 82. Processing: Step S8) can be performed to attempt connection to the external network 4.

  In this way, the consistency between the time information 17 held by the communication unit 11 and the validity period 82 of the server certificate 8 can be examined more appropriately and efficiently than before. Therefore, security can be ensured at the time of connection to the external network 4 and efficient network connection can be established. In addition, since it is not necessary for the user to manually set the time information 17, the load on the user is not increased, and an increase in operation cost can be avoided.

  Further, in the present embodiment, in the first authentication, as a process when the time information 17 is old for some reason and may actually be within the valid period 82, the time within the valid period 82 is converted to the time information 17. Is temporarily set as (step S8). In this case, the first authentication (time verification) can be surely succeeded for the time being and the connection to the external network 4 can be attempted. Therefore, it is possible to avoid the inconvenience that the connection service is not started because the internal clock has stopped for some reason even though it has a valid server certificate 8, and the operation for that purpose is avoided. An increase in cost can also be avoided.

  In this embodiment, when mutual authentication is successful and a connection service to the external network 4 using the server certificate 8 is started, communication is performed by acquiring correct time information from the NTP server 6 on the external network 4. The time update process (step S7) which synchronizes the time information 17 of the part 11 with this is performed. As a result, the time information 17 can be corrected, and the consistency between the time information 17 of the communication unit 11 and the validity period 82 of the server certificate 8 can be correctly verified in subsequent server authentication.

(Modification)
In the above embodiment, the communication unit 11 acquires the correct current time by connecting to the NTP server 6 on the external network 4, but there may be a case where the correct current time can be acquired other than via the external network 4. Therefore, when the correct current time can be acquired by such a method, the time management unit 15 performs a process of updating the time information 17 at that time. A device other than the devices on the external network 4 that can supply correct time information is, for example, a device having an internal clock that exists in the local area network 2. Therefore, the correct current time can be acquired from such a device via the local area network 2.

  In addition, the communication unit 11 includes various types of radio wave information including time information, such as GPS information, beacons, radio wave information for radio clocks, radio wave information supplied from mobile phone base stations, radio waves for digital television and FM multiplex broadcasting. When a reception unit that receives information and the like is provided and used in an environment in which such radio wave information can be received, the current time can be extracted by appropriately receiving the radio wave information. The time management unit 15 updates the time information 17 held by the communication unit 11 when the correct current time is acquired by these methods. If the time information 17 is updated, the authentication unit 16 can perform server authentication using the updated time information. Therefore, the first authentication can be performed more correctly, and the server authentication can be performed more accurately and efficiently.

DESCRIPTION OF SYMBOLS 1 ... Printer, 2 ... Local area network, 3 ... Router, 4 ... External network (network), 5 ... Management server, 6 ... NTP server, 7 ... Authentication server, 8 ... Server certificate, 11 ... Communication part (communication device) , 12 ... Printing section, 13 ... Control section, 14 ... Storage section, 15 ... Time management section, 16 ... Authentication section, 17 ... Time information, 81 ... Authentication information, 82 ... Valid period, P1 ... Start point, P2 ... End point, T1 ... 1st period, T2 ... 2nd period, T3 ... 3rd period

Claims (6)

When connecting to a network using a server certificate, a control method for a communication apparatus that performs authentication of the validity period is set the server certificate,
Before Ki認 card, point shown time information by the communication device is held is, prior to the beginning of the expiration time, the range of the validity period, whether it is a later than the end time of the validity period Performing a first authentication step for determining
As a result of the determination in the first authentication step,
Wherein the time information is the time indicated, when it is later than the end time of the validity period, stops the connection to the network using the server certificate,
Time indicated by the time information is, wherein when a range of the effective period, performs the second authentication step of judging the other authentication information contained in the server certificate,
Time indicated by the time information is, wherein when it is before the start of the validity period, temporarily sets the time information to the preset information indicating the time within the range of the effective period, again the first A control method for a communication apparatus, characterized in that an authentication step is executed . When receiving the information indicating the current time without going through the network, it updates the time information to the current time received, by using the time information after the update, executing the first authentication step The method for controlling a communication apparatus according to claim 1 . When connection to the network using the server certificate becomes possible,
The method of controlling a communication device according to claim 1 or 2 , wherein a time update step of updating the time information to a current time acquired via the network is executed. The method of controlling a communication device according to claim 3 , wherein the time update step updates the time information on condition that a time difference between the time information and the current time is equal to or greater than a preset threshold value. . A time management unit for holding time information;
When connecting to a network using a server certificate has an authentication unit for authenticating the validity period is set the server certificate,
The authentication unit
Before Ki認 card, when the time information the time management unit is held indicated, before the beginning of the expiration time, the range of the validity period, is either later than the end of the expiration time Perform first authentication to determine whether
As a result of the determination of the first authentication,
Wherein the time information is the time indicated, when it is later than the end time of the validity period, stops the connection to the network using the server certificate,
Time indicated by the time information is, if it is within the scope of the validity period, performing a second authentication to review other authentication information contained in the server certificate,
Time indicated by the time information is, wherein when it is before the start of the validity period, temporarily sets the time information to the preset information indicating the time within the range of the effective period, again the first A communication device that performs authentication . A communication device according to claim 5 ;
A printer that prints data received via the communication device on a print medium.

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