JP6315080B2 - Authentication device, authentication system, and program - Google Patents

Description

  The present invention relates to an authentication technique using an image.

  Conventionally, a technique for performing user authentication using user identification information and a password is known. In addition, in order to prevent spoofing due to a password being known to a third party, there is a technique for further enhancing safety by element authentication other than the password. For example, Patent Literature 1 discloses an authentication method that uses a color that is selectively displayed in a terminal screen area as a password.

JP 2012-181716 A

  In the method of authenticating the user only with the password, there is a problem that when a simple password that can be easily guessed is used, the password is guessed by a malicious third party and spoofing is allowed. In order to make it difficult for a third party to guess the password, if you increase the character type used for the password, lengthen the password string, or change the password regularly, you may forget the password. There was a problem that the password was leaked due to the third party seeing the memo with the password written down.

  On the other hand, when using two-factor authentication, it is necessary to distribute an authentication token or introduce a biometric authentication mechanism, and the service provider must bear a large cost for user authentication. It was. Moreover, in patent document 1, in order to raise the tolerance with respect to the analogy of the password by the attacker who intercepts communication, it is necessary to increase the color which a user should memorize | store, and there exists a problem that a user's burden becomes large. . Therefore, the main object of the present invention is to provide an authentication device, an authentication system, and a program that can suitably execute highly secure user authentication without requiring a complicated password.

  In one aspect of the present invention, the authentication device includes a storage unit that stores, for each user, an image group constituting an authentication image set for each user, and a connection that receives a connection request including user identification information from the terminal. For each image group, a request reception unit generates an authentication table indicating the image group candidate set for the user indicated by the user identification information and a code corresponding to the candidate, and transmits the authentication table to the terminal. Means, a response receiving means for receiving a code corresponding to an image group candidate selected by the user of the terminal for each of the authentication tables, and the code received by the response receiving means is set to the user Determining means for determining whether or not the code matches the group code.

  The authentication apparatus includes a storage unit, a connection request receiving unit, an authentication table transmitting unit, a response receiving unit, and a determining unit. The storage unit stores, for each user, an image group constituting an authentication image set for each user. The connection request receiving unit receives a connection request including user identification information from the terminal. The authentication table transmission unit generates an authentication table indicating an image group candidate of an authentication image set for the user indicated by the user identification information and a code corresponding to the candidate for each image group constituting the authentication image, Send to the terminal. The response receiving means receives, for each authentication table, a code corresponding to an image group candidate constituting the authentication image selected by the user of the terminal. The determination unit determines whether or not the code received by the response reception unit indicates a code of an image group constituting the authentication image set by the user.

  In this aspect, the user visually stores the authentication image, and the authentication apparatus causes the user of the terminal to select an image group constituting the authentication image as a password. As a result, the authentication device can increase the security by increasing the number of authentication elements without excessively increasing the burden for the user to remember the password.

  In one aspect of the authentication apparatus, the authentication table includes a name indicating the candidate for the image group, and the authentication table transmission unit sets the name indicating the image group set for the user for each authentication session. Change to According to this aspect, the authentication apparatus prevents the name indicating the image group set for the user from being included in the authentication table every time, and the code of the authentication image set for the user can be detected by an attacker who intercepts communication repeatedly. Can be suitably suppressed.

  In another aspect of the authentication apparatus, the storage unit may include at least one of an image indicating a theme of the authentication image, an image indicating a background of the authentication image, and a conversion instruction of the theme as the image group. Remember one. In this way, multi-factor authentication based on one authentication image by using an image indicating the subject displayed on the authentication image, a background image, or a conversion instruction of the subject as an image group of authentication images. Can be suitably performed.

  In another aspect of the authentication apparatus, the authentication apparatus further includes key generation means for generating a session key shared with the terminal, and the authentication table transmission means encrypts and transmits the authentication table based on the session key. According to this aspect, user authentication can be executed more safely.

  In another aspect of the present invention, there is provided an authentication system comprising any one of the above-described authentication devices and a terminal connected to the authentication device via a network, wherein the terminal receives each of the authentication tables. Corresponding to a table receiving means, a selection receiving means for selectively displaying an image representing a candidate of the image group included in the authentication table for each of the authentication tables, and the image selected for each authentication table Response transmitting means for transmitting a code corresponding to an image group candidate to be transmitted to the authentication device. According to this aspect, the authentication system can perform user authentication by causing the user to suitably specify an authentication image necessary for user authentication.

  In one aspect of the authentication system, the transmission order of codes corresponding to the candidates to be transmitted for each authentication table is changed for each authentication session. Thereby, the authentication system can make it difficult for the communication interceptor to guess the code of the authentication image.

  In another aspect of the authentication system, the authentication table includes a name indicating a candidate for the image group, and the authentication table transmission unit includes the image group set for the user to be included in the authentication table. The name to be shown is determined by applying an algorithm shared with the terminal, and the selection receiving unit applies the algorithm to the name showing the image group set for the user included in the authentication table. Then, the image to be displayed is recognized. As a result, the authentication system can change only the name of the image group for each authentication session without changing the entity of the image group set for the user, and communicates the code of the authentication image set for the user. It is possible to suitably suppress analogy to the eavesdropper.

  According to still another aspect of the present invention, there is provided a terminal device connected to the authentication device according to any one of the above through a network, an authentication table receiving unit that receives each of the authentication tables from the authentication device, and the authentication table A selection receiving means for selectively displaying an image representing the image group candidate included in the authentication table, and an image group candidate corresponding to the image selected for each authentication table. Response transmitting means for transmitting a code to the authentication device, the authentication table includes a name indicating the candidate image group, and the authentication device is set to the user included in the authentication table. The name indicating the image group is determined by applying an algorithm shared with the terminal device, and the selection receiving unit is Serial by applying the algorithm to the name indicating the image group set to the user contained in the authentication table, recognizes an image to be displayed.

  In this aspect, the terminal device performs user authentication by causing the user to preferably designate an image group that constitutes an authentication image necessary for user authentication. At this time, the terminal device can intercept the code of the authentication image set for the user by changing only the name of the image group for each authentication session without changing the entity of the image group set for the user. It is possible to suitably suppress analogy to a person.

  In still another aspect of the present invention, a program causes a computer to function as any one of the authentication devices described above. The authentication apparatus according to the present invention can be configured by installing this program in a computer and causing it to function. The program causes the computer to function as the terminal device described above. By installing this program in a computer and causing it to function, the terminal device according to the present invention can be configured.

  According to the authentication device and the authentication system of the present invention, user authentication can be performed safely based on an image group constituting an authentication image set for each user without requiring a complicated password input. .

The structure of the transaction system which concerns on 1st Embodiment is shown. The block diagram of an authentication server is shown. The block diagram of a user terminal is shown. An example of the data structure of a password table is shown. An example of the data structure of each authentication table produced | generated by the 1st authentication session is shown. An example of the data structure of each authentication table produced | generated by the 2nd authentication session is shown. It is a flowchart which shows the procedure of the authentication process which concerns on 1st Embodiment. The example of a display of a theme image selection screen is shown. The example of a display of a background image selection screen is shown. It is an example of a display of a conversion instruction | indication selection screen. The structure of the transaction system which concerns on a modification is shown. It is a flowchart which shows the procedure of the authentication process which concerns on a modification. It is an example of the table which shows the registration file name of the theme image used in each authentication session. (A) shows the 1st authentication table produced | generated by the 1st authentication session. (B) shows a first authentication table generated in the second authentication session. It is a flowchart which shows the procedure of the authentication process which concerns on 3rd Embodiment.

  Hereinafter, first to third embodiments suitable for carrying out the present invention will be described with reference to the drawings.

<First Embodiment>
[Configuration of trading system]
FIG. 1 shows a configuration of a transaction system according to the first embodiment. The transaction system includes a service provider server 1 managed by a service provider such as a bank, and a user terminal 3 used by a user who receives the above service. The service provider server 1 and the user terminal 3 perform data communication via a communication network 2 such as the Internet.

  The service provider server 1 includes two servers, an authentication server 1A that performs user authentication of the user terminal 3 and a transaction server 1B that performs processing related to transactions after the user authentication. The authentication server 1A and the transaction server 1B exchange data necessary for executing the assigned processing as necessary.

  The authentication server 1A causes the user terminal 3 to specify an authentication image (also referred to as “authentication image”) registered for each user from the image group, and an image configured based on the specified image group is displayed. If it matches the registered authentication image, the user is authenticated as a valid user. When the authentication server 1A authenticates the user terminal 3 as a valid user, the transaction server 1B transmits display information of a transaction screen to the user terminal 3 or performs a transaction from the user terminal 3. Receive input information on the screen. Thereby, transaction server 1B performs the transaction which the user of user terminal 3 desires.

  The user terminal 3 is a communication terminal such as a smartphone, for example, and has a display 41 on which a touch panel 42 is stacked in the example of FIG. The user terminal 3 communicates with the authentication server 1A and receives user authentication from the authentication server 1A before executing processing related to the transaction with the transaction server 1B.

[Configuration of authentication server]
FIG. 2 is a block diagram of the authentication server 1A. The authentication server 1A includes a display unit 11 such as a display, an input unit 12 such as a keyboard, a storage unit 13, a communication unit 14 that performs data communication, and a control unit 15. Each of these elements is connected to each other via a bus line 10.

  The storage unit 13 is configured by a memory such as a hard disk or a flash memory. The storage unit 13 stores a program executed by the control unit 15. The storage unit 13 stores a table (also referred to as “password table Tp”) indicating image groups constituting authentication images set for each user. The password table Tp according to the present embodiment includes, for each user, a “theme image” indicating an object displayed as the theme of the authentication image, a “background image” displayed on the background of the object, A “conversion instruction” for designating the direction of the object is stored as an image group of authentication images. A specific example of the password table Tp will be described later with reference to FIG.

  The control unit 15 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like (not shown), and performs various controls on each component in the authentication server 1A.

  For example, when the authentication server 1A receives a connection request from the user terminal 3, the control unit 15 sets the image group registered in the password table Tp for each type of image group that forms the authentication image. A table indicating candidates (also referred to as “authentication table Tc”) is generated and transmitted to the user terminal 3. In the present embodiment, the authentication table Tc includes the file name of the theme image or background image or the command name of the conversion instruction, and the authentication code associated therewith. And the control part 15 determines whether the user of the user terminal 3 is a valid user by receiving the authentication code which shows the selection result in the authentication table Tc from the user terminal 3. . The control unit 15 functions as a “connection request receiving unit”, “authentication table transmitting unit”, “response receiving unit”, “determination unit”, and a program executed by a computer.

  Hereinafter, the authentication table Tc including the file name of the theme image is also referred to as “first authentication table Tc1”, and the authentication table Tc including the file name of the background image is also referred to as “second authentication table Tc2”. The authentication table Tc including the command name is also referred to as “third authentication table Tc3”.

[User terminal configuration]
FIG. 3 is a block diagram of the user terminal 3. The user terminal 3 includes a display unit 31 such as a display 41, an input unit 32 such as a touch panel 42, a storage unit 33, a communication unit 34 that performs data communication, and a control unit 35. These elements are connected to each other via a bus line 30.

  The storage unit 33 is configured by a memory such as a hard disk or a flash memory. The storage unit 33 stores a program executed by the control unit 35. In addition, the storage unit 33 stores image data corresponding to each file name of the theme image included in the first authentication table Tc1 transmitted from the authentication server 1A. In addition, the storage unit 33 stores image data corresponding to each file name of the background image included in the second authentication table Tc2. Further, the storage unit 33 stores the setting of the orientation of the theme image corresponding to each command name of the conversion instruction included in the third authentication table Tc3.

  The control unit 35 includes a CPU, a ROM, a RAM, and the like (not shown), and performs various controls on each component in the user terminal 3. The control unit 35 performs a predetermined process by executing a program stored in the storage unit 33. For example, the control unit 35 displays a plurality of images on the display 41 based on the authentication table Tc received from the authentication server 1A, and accepts selection by the touch panel 42 or the like. Then, the control unit 35 transmits an authentication code corresponding to the image selected by the user to the authentication server 1A. The control unit 35 functions as an “authentication table receiving unit”, a “selection receiving unit”, a “response transmitting unit”, and a program executed by the computer in the present invention.

[Table data structure]
Next, specific examples of the password table Tp and the authentication table Tc will be described.

  FIG. 4 shows an example of the data structure of the password table Tp stored in advance in the storage unit 13. As shown in FIG. 4, in the password table Tp, the file name of the theme image, the file name of the background image, and the command name of the conversion instruction are associated with each user ID (user identification information).

  Specifically, the user ID of each user registered in the authentication server 1A is recorded in the item “user ID”. In the items “theme image” and “background image”, file names of the theme image and the background image are recorded, respectively. For example, the file name “Dog1.jpg” of the theme image and the file name “back2.jpg” of the background image are associated with the user ID “0001”. In the item “conversion instruction”, a command name for specifying a direction for displaying an object to be the subject of the authentication image on the display unit is recorded. For example, the command name “Rotate0” is associated with the user ID “0001”. Here, “Rotate 0” and “Rotate 90” indicate that the orientation of the target object of the authentication image is rotated by 0 ° and 90 ° in the counterclockwise direction from the standard state, respectively. “Fliphorizontal” indicates that the orientation of the target object of the authentication image is reversed left and right from the standard state. Similarly, “FlipVertical” (not shown) indicates that the orientation of the target object of the authentication image is inverted from the standard state.

  5A to 5C show the data structure of each authentication table Tc generated in the first authentication session with the user ID “0001”. Specifically, FIG. 5A shows the data structure of the first authentication table Tc1 including the file name of the theme image. FIG. 5B shows the data structure of the second authentication table Tc2 including the file name of the background image. FIG. 5C shows the data structure of the third authentication table Tc3 including the command name of the conversion instruction.

  Each authentication table Tc is randomly selected as a file name or command name (also referred to as “registered file name” or “registered command name”) registered in the password table Tp in association with the person to be authenticated. Incorrect file name or command name (also referred to as “dummy file name” or “dummy command name”). Each file name or each command name in each authentication table Tc is associated with a unique authentication code generated at random. In FIGS. 5A to 5C, a column corresponding to the registered file name or registered command name of the user ID “0001” who is the authentication target is surrounded by a broken line frame.

  Specifically, in the left column of the first authentication table Tc1 shown in FIG. 5A, the registered file name “Dog1.jpg” of the theme image registered in the password table Tp in association with the user ID “0001”. ”And a dummy file name of a theme image such as“ Cat3.jpg ”. The above-mentioned dummy file name is the file name of the image for incorrect answer of the theme image, and a predetermined number is randomly selected for each authentication session. The image data indicated by the registered file name and the dummy file name is stored in advance by the storage unit 33 of the user terminal 3. The right column of the first authentication table Tc1 is associated with a unique authentication code for each file name in the left column.

  In the left column of the second authentication table Tc2 shown in FIG. 5B, the background image such as the registered file name “back2.jpg” and “back1.jpg” of the background image corresponding to the user ID “0001” is displayed. The dummy file names are listed. A predetermined number of the above dummy file names are randomly selected for each authentication session. The registered file name and the image data indicated by each dummy file name are stored in advance by the storage unit 33. Further, in the right column of the second authentication table Tc2 shown in FIG. 5B, a unique authentication code is associated with each file name in the left column.

  Similarly, in the left column of the third authentication table Tc3 shown in FIG. 5C, a registration command name “Rotate0” and a dummy command name such as “Rotate90” corresponding to the user ID “0001” are displayed. Are lined up. A predetermined number of the above dummy command names are randomly selected for each authentication session. The contents of the subject image conversion instruction indicated by the registered command name and each dummy command name are stored in advance in the storage unit 33. Also, a unique authentication code is associated with each command name in the left column in the right column of the third authentication table Tc3 shown in FIG.

  Further, each authentication code included in the authentication table Tc is randomly generated for each authentication session. 6A to 6C show the data structure of each authentication table Tc generated in the second authentication session of the user ID “0001”.

  In both the first authentication table Tc1 shown in FIG. 5A and the first authentication table Tc1 shown in FIG. 6A, the registered file name “Dog1.jpg” of the theme image corresponding to the user ID “0001” is stored. There is a column shown (see dashed line frame). On the other hand, the authentication codes corresponding to these registered file names are “37Yxp ″} 6” in the case of FIG. 5A, and “jr3O2qnbT” in the case of FIG. Similarly, in both the second authentication table Tc2 shown in FIG. 6B and the second authentication table Tc2 shown in FIG. 6B, the registered file name “back2. A column indicating “jpg” is present (see a broken line frame). On the other hand, the authentication codes corresponding to these registered file names are different from each other. Also, in both the third authentication table Tc3 shown in FIG. 6C and the third authentication table Tc3 shown in FIG. 6C, the conversion command registration command name “Rotate0” corresponding to the user ID “0001” is set. There is a column shown (see dashed line frame). On the other hand, authentication codes corresponding to these registered command names are different from each other.

[Processing flow]
FIG. 7 is a flowchart showing a procedure of authentication processing executed by the user terminal 3 and the authentication server 1A. The user terminal 3 and the authentication server 1A execute the processing of the flowchart shown in FIG. 7 when a predetermined operation is performed on the user terminal 3.

  First, the user terminal 3 displays a login screen by a Web browser based on the display information received from the service provider server 1, and accepts an input such as a login ID (step S101). Then, after confirming the input content on the login screen, the user terminal 3 transmits a connection request including the input user ID to the authentication server 1A (step S102).

  Next, the authentication server 1A generates authentication tables Tc1 to Tc3 for each type of image group constituting the authentication image based on the user ID included in the connection request received from the user terminal 3 (step S103). . Specifically, first, the authentication server 1A extracts the registration file name of the theme image and background image and the registration command name of the conversion instruction corresponding to the user ID included in the connection request from the password table Tp, and these The dummy file name and dummy command name are selected at random. Next, the authentication server 1A randomly generates an authentication code corresponding to the extracted or selected file name and command name, thereby generating authentication tables Tc1 to Tc3 as shown in FIG. Then, the authentication server 1A transmits the generated authentication tables Tc1 to Tc3 to the user terminal 3 (step S104).

  Then, the user terminal 3 displays a screen for selecting a theme image (also referred to as “theme image selection screen”) based on the received first authentication table Tc1, and accepts an input for selecting the theme image (step S105). ). In this case, for example, the user terminal 3 reads out the images indicated by the file names included in the first authentication table Tc1 from the storage unit 33 and displays them in a selectable manner. The theme image selection screen will be described later with reference to FIG. Then, when any image is selected on the theme image selection screen, the user terminal 3 transmits an authentication code corresponding to the file name of the selected image to the authentication server 1A (step S106).

  Next, the user terminal 3 displays a screen for selecting a background image (also referred to as a “background image selection screen”) based on the received second authentication table Tc2, and accepts an input for selecting the background image (step). S107). In this case, for example, the user terminal 3 reads out the image indicated by each file name included in the second authentication table Tc2 from the storage unit 33, displays the image combined with the theme image selected in step S105. The background image selection screen will be described later with reference to FIG. Then, when any image is selected on the background image selection screen, the user terminal 3 transmits an authentication code corresponding to the file name of the background image combined with the selected image to the authentication server 1A ( Step S108).

  Furthermore, based on the received third authentication table Tc3, the user terminal 3 displays a screen for selecting the direction of the theme image (also referred to as “conversion instruction selection screen”), and inputs for selecting the direction of the theme image. Accept (step S109). In this case, the user terminal 3 converts and displays the theme image selected in step S105 according to the conversion instruction indicated by each command name included in the third authentication table Tc3. The conversion instruction selection screen will be described later with reference to FIG. Then, when any image is selected on the conversion instruction selection screen, the user terminal 3 transmits an authentication code corresponding to the command name of the conversion instruction applied to the selected image to the authentication server 1A (step). S110).

  Then, the authentication server 1A collates the authentication code received from the user terminal 3 (step S111). Specifically, the authentication server 1A determines whether the file name of the theme image indicated by the authentication code transmitted in step S106 matches the registered file name of the theme image, and the authentication code transmitted in step S108. Whether the background image file name shown matches the registered image name of the background image, and the command name of the conversion instruction indicated by the authentication code transmitted in step S110 matches the registered command name of the conversion instruction Judge whether to do. When the file name and command name indicated by the authentication code received from the user terminal 3 match the registered file name and registered command name stored in the password table Tp, the authentication server 1A has succeeded in user authentication. Judge. In this case, the authentication server 1A permits communication related to the transaction between the user terminal 3 and the transaction server 1B, and the user terminal 3 starts communication with the transaction server 1B. On the other hand, if the file name or command name indicated by the authentication code received from the user terminal 3 does not match the registered file name or registered command name stored in the password table Tp, the authentication server 1A failed in user authentication. Judge. In this case, the authentication server 1A does not permit communication related to the transaction between the user terminal 3 and the transaction server 1B.

[Display example]
Next, a display screen example displayed by the user terminal 3 will be described with reference to the authentication table Tc shown in FIG. 5 and FIGS. 8 to 10.

  FIG. 8 is an example of a theme image selection screen displayed by the user terminal 3 in step 105 of FIG. In FIG. 8, the user terminal 3 displays the images 50 to 53 corresponding to the file names included in the first authentication table Tc1 received from the authentication server 1A on the display 41 as candidates for the theme image. Here, the image 50 corresponds to the registered file name “Dog1.jpg” in the first authentication table Tc1 shown in FIG. 5A, the image 51 corresponds to the dummy file name “Cat3.jpg”, and the image 52 Corresponds to the dummy file name “wine1.jpg”, and the image 53 corresponds to the dummy file name “Dog5.jpg”.

  As described above, in step 105 of FIG. 7, the user terminal 3 reads the image indicated by the file name included in the first authentication table Tc1 from the storage unit 33 and displays it in a selectable manner. In the example of FIG. 8, the user terminal 3 detects that the image 50 has been selected by the touch panel 42, and transmits an authentication code “37Yxp ″} 6” corresponding to the image 50 to the authentication server 1A.

  FIG. 9 is an example of a background image selection screen displayed on the user terminal 3 in step S107 of FIG. In FIG. 9, the user terminal 3 combines the background image indicated by the four file names included in the second authentication table Tc2 received from the authentication server 1A with the image 50 selected on the theme image selection screen of FIG. The displayed images 50A to 50D are displayed on the display 41.

  Here, the image 50A is an image obtained by combining the image 50 and the background image indicated by the registered file name “back2.jpg” in the second authentication table Tc2 illustrated in FIG. In this case, the user terminal 3 generates and displays the image 50A by replacing the background of the dog displayed in the image 50 with the background image indicated by the file name “back2.jpg”. Similarly, the image 50B is an image obtained by combining the image 50 and the background image indicated by the dummy file name “back1.jpg”, and the image 50C is the background image indicated by the image 50 and the dummy file name “back5.jpg”. The image 50D is an image obtained by combining the image 50 and the background image indicated by the dummy file name “back7.jpg”.

  As described above, the user terminal 3 reads the background image indicated by each file name included in the second authentication table Tc2 from the storage unit 33, and displays the background image combined with the image 50 that is the theme image selected in FIG. . In the example of FIG. 9, the user terminal 3 detects that the image 50 </ b> A has been selected by the touch panel 42, and the authentication code “back2.jpg” combined with the image 50 </ b> A is associated with the authentication code “back2.jpg”. 7uIeV53T "is transmitted to the authentication server 1A.

  FIG. 10 is an example of a conversion instruction selection screen displayed on the user terminal 3 in step S109 of FIG. In FIG. 10, the user terminal 3 gives a conversion instruction indicated by four command names included in the third authentication table Tc3 received from the authentication server 1A to the image 50A selected on the background image selection screen of FIG. The applied images 50 </ b> Aa to 50 </ b> Ad are displayed on the display 41.

  Here, the image 50Aa is an image obtained by rotating the dog displayed on the image 50A by 0 ° in accordance with the conversion instruction indicated by the command name “Rotate0” of the third authentication table Tc3 shown in FIG. The image 50Ab is an image obtained by horizontally inverting the dog displayed on the image 50A in accordance with the conversion instruction indicated by the command name “FlipVertical”. The image 50Ac is an image obtained by rotating the dog displayed in the image 50A by 90 ° in accordance with the conversion instruction indicated by the command name “Rotate90”. The image 50Ad is an image obtained by inverting the dog displayed on the image 50A upside down in accordance with the conversion instruction indicated by the command name “Fliporyzontal”.

  As described above, the user terminal 3 converts the subject image portion in the image 50A selected in FIG. 9 according to the conversion instruction indicated by each command name included in the third authentication table Tc3, and converts the converted image. Is displayed in a selectable manner. In the example of FIG. 10, the user terminal 3 detects that the image 50Aa has been selected by the touch panel 42, and sends the authentication code “2y0Qmv54” corresponding to the command name “Rotate0” applied to the image 50Aa to the authentication server. Send to 1A.

[Operational effects of the transaction system of the first embodiment]
According to the transaction system of the first embodiment, the authentication server 1A allows the user of the user terminal 3 to specify a plurality of image groups for specifying an authentication image set for each user, thereby performing user authentication. I do. As a result, the authentication server 1 can increase the number of authentication elements and increase the safety without excessively burdening the user to remember the password.

[Modification]
Next, a modification of the first embodiment will be described. The following modifications may be applied in any combination to the above-described embodiment.

(Modification 1)
In the first embodiment, the authentication server 1A allows a user to specify a theme image, a background image, and a conversion instruction as an image group constituting an authentication image used for user authentication. However, the types of image groups constituting the authentication image applicable to the present invention are not limited to the above three types.

  For example, instead of or in addition to these, the authentication server 1A allows the user to specify the size and color of the object indicated by the theme image, the background color and pattern, etc. as an image group constituting the authentication image. May be. Further, the types of image groups constituting the authentication image are not limited to three, and may be two or more. Even in this case, the authentication server 1A stores the password table Tp indicating the image group that configures the authentication image set for each user, and performs authentication for each image group that configures the authentication image. A table Tc is generated and transmitted to the user terminal 3. Further, the user terminal 3 displays a selection image for each authentication table Tc received from the authentication server 1A, and transmits an authentication code corresponding to the selected image to the authentication server 1A.

(Modification 2)
Instead of the flowchart of FIG. 7, the user terminal 3 may randomly change the order in which the user selects the theme image, the background image, and the orientation of the theme image for each authentication session. That is, the user terminal 3 may randomly determine the execution order of steps S105, S107, and S109 for each authentication session. For example, the user terminal 3 may allow the user to specify the orientation of the background image or the theme image before the theme image. In this case, on the conversion instruction selection screen, the user terminal 3 may apply and display a conversion instruction for each command name in the third authentication table Tc3 on the temporary theme image.

  Further, in addition to or instead of the selection order described above, the user terminal 3 randomly changes the transmission order of the authentication code indicating the theme image, the background image, and the orientation of the theme image selected by the user for each authentication session. You may change to That is, the user terminal 3 may randomly determine the execution order of steps S106, S108, and S110 for each authentication session. Thereby, the tolerance to the estimation of the registration file name and registration command name by a communication interceptor can be improved suitably.

(Modification 3)
The configuration of the transaction system shown in FIG. 1 is an example, and the configuration to which the present invention is applicable is not limited to this. For example, the service provider server 1 may be composed of a single server.

  FIG. 11 shows a configuration example of a transaction system according to a modification. In FIG. 11, the service provider server 1 has both functions of the authentication server 1A and the transaction server 1B shown in FIG. In the example of FIG. 11, the user terminal 3 is realized by a personal computer instead of the mobile terminal. Even in the configuration example of FIG. 11, when there is a connection request, the service provider server 1 transmits the authentication table Tc to the user terminal 3, and the user terminal 3 displays the user selection result. The authentication code based on this is transmitted to the service provider server 1. Thereby, the service provider server 1 can perform user authentication suitably.

  In another example, the service provider server 1 may be composed of three or more servers. For example, the authentication server 1A may be configured by two servers, a server that stores the password table Tp and a server that executes the flowchart of FIG. Even in this case, each server is connected to other servers via a network such as the communication network 2 and exchanges information necessary for processing.

(Modification 4)
In the example of the flowchart of FIG. 7, the user terminal 3 individually transmits the authentication code in steps S106, S108, and S110. Instead of this, the user terminal 3 may receive the input for selecting each of the theme image, the background image, and the orientation of the theme image, and then transmit the authentication code in a batch.

  FIG. 12 is a flowchart showing a procedure of authentication processing according to the present modification. In the flowchart shown in FIG. 12, first, the user terminal 3 and the authentication server 1A execute the processes from step S201 to S205 in the same manner as steps S101 to S105 in FIG. Then, after accepting an input for selecting a theme image in step S205, the user terminal 3 accepts an input for selecting a background image in step S206 without sending an authentication code. Similarly, after accepting an input for selecting a background image in step S206, the user terminal 3 accepts an input for selecting the orientation of the theme image in step S207 without transmitting an authentication code.

  In step S208, the user terminal 3 collectively transmits the three authentication codes to be transmitted in steps S106, S108, and S110 in FIG. Also by this, the user terminal 3 can suitably transmit the authentication code corresponding to the image selected by the user to the authentication server 1A. In step S209, the authentication server 1A collates the received authentication code as in step S111 in FIG.

  Note that, when the user terminal 3 transmits three authentication codes together, the order of the authentication codes may be rearranged randomly for each authentication session. Thereby, the tolerance to the estimation of the registration file name and registration command name by a communication interceptor can be improved suitably.

Second Embodiment
In the second embodiment, in addition to the processing of the first embodiment, the authentication server 1A extracts, for each authentication session, a registration file name and a registration command name that are extracted from the password table Tp and included in the authentication table Tc with a predetermined algorithm. (Also referred to as “name change algorithm”). Accordingly, the user terminal 3 prevents the registered file name and the registered command name from being inferred even when the authentication table Tc is intercepted repeatedly.

  In this case, the authentication server 1A and the user terminal 3 store the same name change algorithm in advance. Then, the authentication server 1A changes the names by applying a name change algorithm to the registered file name and the registered command name included once in the authentication table Tc. Similarly, when the user terminal 3 receives the authentication table Tc, the user terminal 3 changes these names by applying a name change algorithm to the registered file name and the registered command name included in the authentication table Tc. Here, before and after the application of the name change algorithm, the image indicated by the registered file name and the conversion instruction indicated by the registered command name are unchanged. Thereby, the authentication server 1A and the user terminal 3 can suitably change these names without changing the entity indicated by the registration file name and the registration command name for each authentication session.

  Here, a specific example in which a name change algorithm that rotates and uses a set of ten file names with respect to a registered file name of a theme image will be described with reference to FIGS. 13 and 14.

  FIG. 13 is an example of a table indicating registered file names of theme images used in each authentication session with the user ID “0001”. FIG. 14A shows the first authentication table Tc1 generated in the first authentication session of the user ID “0001”, and FIG. 14B is generated in the second authentication session. The 1st authentication table Tc1 is shown. Here, it is assumed that the theme image of the user ID “0001” indicates the dog image 50 shown in FIG.

  First, the authentication server 1A and the user terminal 3 store in advance the table shown in FIG. When the authentication server 1A performs the first authentication session with the user terminal 3, the authentication server 1A refers to the table shown in FIG. 13 and, as shown in FIG. 14A, the theme image (that is, the dog image 50). ) Is set to “Dog1.jpg”, and the first authentication table Tc1 is generated. The user terminal 3 that has received the first authentication table Tc1 refers to the table shown in FIG. 13 so that the file name “Dog1.jpg” included in the first authentication table Tc1 is the file of the dog image 50. It is recognized as a name. Then, the user terminal 3 displays a theme image selection image that displays an image corresponding to each file name included in the first authentication table Tc1.

  Similarly to the table shown in FIG. 13, the authentication server 1A and the user terminal 3 store in advance a table for determining the registered file name of the background image and the registered command name of the conversion instruction, and authenticate based on the table. The table Tc is generated and the background image selection screen and the conversion instruction selection screen are displayed.

  Next, when performing the second authentication session with the user terminal 3, the authentication server 1A refers to the table shown in FIG. 13 and, as shown in FIG. 14B, the theme image (that is, the dog image). 50) is set to “Dog2.jpg”, and the first authentication table Tc1 is generated. Further, the user terminal 3 that has received the first authentication table Tc1 refers to the table shown in FIG. 13 in the same way as the authentication server 1A, so that the file name “Dog2.jpg” included in the first authentication table Tc1 is obtained. The file name of the dog image 50 is recognized. Then, the user terminal 3 displays a theme image selection screen that displays an image corresponding to each file name included in the first authentication table Tc1.

  And even if it is a case where the authentication server 1A and the user terminal 3 perform the authentication session after the 3rd time, registration of a theme image (namely, dog image 50) by referring to the table shown in FIG. The file name is determined, and the first authentication table Tc1 is generated and the theme image selection screen is displayed. Similarly, the authentication server 1A and the user terminal 3 refer to the table for determining the file name of the background image and the command name of the conversion instruction, thereby obtaining the registered file name of the background image and the registered command name of the conversion instruction. The authentication table Tc is generated and the background image selection screen and the conversion instruction selection screen are displayed. Thereby, the authentication server 1A and the user terminal 3 can suitably change the registration file name and the registration command name for each authentication session without changing the entity indicated by the registration file name and the registration command name.

[Effects of Second Embodiment]
In the second embodiment, the authentication server 1A and the user terminal 3 apply the name change algorithm to the registration file name and the registration command name for each authentication session, without changing the entity indicated by these, Change only the name. As a result, the registration table name and the registration command name that are different for each authentication session are included in the authentication table Tc, and the user terminal 3 repeats the registration file name and the registration command name having the same name in the authentication table Tc. It can be prevented from being included. Therefore, even when there is an attacker who repeatedly intercepts the authentication table Tc, the attacker always searches for the same file name or command name in each authentication session. Cannot make an estimate. In addition, the transaction system of the second embodiment has the same effects as the transaction system of the first embodiment.

[Modification of Second Embodiment]
In the second embodiment, the modifications of the first embodiment may be applied in any combination.

<Third Embodiment>
In the third embodiment, in addition to the first embodiment, the authentication server 1A and the user terminal 3 generate and share an encryption session key for each authentication session, and use the session key to generate an authentication table Tc. And encryption of communication of authentication code. As in the second embodiment, this also prevents the user terminal 3 from guessing the registered file name and the registered command name by a person who repeatedly intercepts the authentication table Tc.

  FIG. 15 is a flowchart showing a procedure of authentication processing when a session key is generated and shared by the Diffie-Hellman (DH) key sharing method. Note that it is assumed that the authentication server 1A and the user terminal 3 share a predetermined prime number “p” and a predetermined primitive root “α” in advance before the execution of FIG.

First, the user terminal 3 generates a different random number “a” for each authentication session (step S301). Next, the user terminal 3 calculates the value “A” based on the following equation (1) (step S302).
A = α ^a mod p (1)

  Next, based on the display information received from the service provider server 1, the user terminal 3 displays a login screen with a Web browser and accepts an input such as a login ID (step S303). Then, after confirming the input content on the login screen, the user terminal 3 transmits a connection request including the input user ID and the value A calculated by the equation (1) to the authentication server 1A (step S304).

Next, the authentication server 1A that has received the connection request generates an arbitrary random number “b” that is different for each authentication session (step S305). Next, the authentication server 1A calculates the value “B” based on the following equation (2) (step S306).
B = α ^b mod p (2)

Next, the user terminal 3 makes a response to the connection request including the calculated value B (step S307). Then, the user terminal 3 that has received the response generates a shared key K based on the following equation (3) (step S308).
K = B ^a mod p = α ^ab mod p (3)

Similarly, the authentication server 1A generates a shared key K based on the following formula (4) (step S309).
K = A ^b mod p = α ^ab mod p (4)

  Then, the authentication server 1A generates the first to third authentication tables Tc1 to Tc3 as in step S103 of FIG. 7, and performs encryption using the key K generated in step S309 (step S310). Then, the authentication server 1A transmits the encrypted authentication table Tc to the user terminal 3 (step S311). Then, the user terminal 3 decrypts the encrypted authentication table Tc with the key K generated in step S308 (step S312). Then, similarly to step S105 of FIG. 7, the user terminal 3 receives an input for selecting the theme image (step S313), encrypts the authentication code corresponding to the selected theme image with the key K, and authenticates the authentication server 1A. (Step S314). Similarly, the user terminal 3 receives an input for selecting a background image (step S315), encrypts an authentication code corresponding to the selected background image with the key K, and transmits it to the authentication server 1A (step S316). Further, the user terminal 3 receives an input for selecting the orientation of the theme image (step S317), encrypts an authentication code corresponding to the selected orientation with the key K, and transmits it to the authentication server 1A (step S318). Then, the user terminal 3 decrypts the received encrypted authentication code with the key K, and compares the authentication code with reference to the password table Tp (step S319).

[Effects of Third Embodiment]
In the third embodiment, the authentication server 1A and the user terminal 3 generate a different common key K for each authentication session, and exchange the authentication table Tc and the authentication code encrypted using the common key K. Thereby, even when the attacker repeatedly performs the interception of the authentication table Tc, similarly to the second embodiment, it is preferable to prevent the attacker from guessing the registered file name and the registered command name. be able to. In addition, the transaction system of 3rd Embodiment has the same effect as the transaction system of 1st Embodiment.
[Modification of Third Embodiment]
In the third embodiment, in addition to the modification of the first embodiment, the following modification 5 may be arbitrarily combined and applied.

(Modification 5)
In the flowchart of FIG. 15, the authentication server 1A and the user terminal 3 generate a common session key by the Diffie-Hellman (DH) key sharing method. Instead, the authentication server 1A and the user terminal 3 may generate and share a session key by any other method. For example, the authentication server 1A and the user terminal 3 may generate a one-time password by a time synchronization method or a challenge and response method, and perform encrypted communication of the authentication table Tc and the authentication code using the one-time password as a session key. .

DESCRIPTION OF SYMBOLS 1 ... Service provider server 1A ... Authentication server 1B ... Transaction server 2 ... Communication network 3 ... User terminal

Claims (10)

Storage means for storing, for each user, an image group constituting an authentication image set for each user;
A connection request receiving means for receiving a connection request including user identification information from the terminal;
An authentication table transmitting means for generating an authentication table indicating a candidate of the image group set for the user indicated by the user identification information and a code corresponding to the candidate for each image group, and transmitting the authentication table to the terminal;
Response receiving means for receiving a code corresponding to an image group candidate selected by the user of the terminal for each authentication table;
Determining means for determining whether or not the code received by the response receiving means matches the code of the image group set for the user;
An authentication device comprising: The authentication table includes a name indicating the candidate image group,
The authentication apparatus according to claim 1, wherein the authentication table transmission unit changes a name indicating the image group set for the user for each authentication session.   The storage means stores, as the image group, at least one of an image indicating a theme of the authentication image, an image indicating a background of the authentication image, and a conversion instruction of the subject. The authentication apparatus according to claim 1 or 2. Key generation means for generating a session key shared with the terminal;
The authentication apparatus according to any one of claims 1 to 3, wherein the authentication table transmitting unit encrypts and transmits the authentication table based on the session key. The authentication device according to any one of claims 1 to 4,
An authentication system having a terminal connected to the authentication device via a network,
The terminal
Authentication table receiving means for receiving each of the authentication tables;
Selection accepting means for selecting each of the authentication tables so that an image representing the candidate image group included in the authentication table can be selected;
Response transmitting means for transmitting a code corresponding to an image group candidate corresponding to the image selected for each authentication table to the authentication device;
An authentication system comprising:   The authentication system according to claim 5, wherein the response transmission unit changes a transmission order of codes corresponding to the candidates to be transmitted for each authentication table for each authentication session. The authentication table includes a name indicating the candidate image group,
The authentication table transmission means determines a name indicating the image group set for the user to be included in the authentication table by applying an algorithm for sharing with the terminal,
The selection accepting unit recognizes an image to be displayed by applying the algorithm to a name indicating an image group set for the user included in the authentication table. 6. The authentication system according to 6. A terminal device connected to the authentication device according to any one of claims 1 to 4 via a network,
Authentication table receiving means for receiving each of the authentication tables from the authentication device;
Selection accepting means for selecting each of the authentication tables so that an image representing the candidate image group included in the authentication table can be selected;
Response sending means for sending a code corresponding to an image group candidate corresponding to the image selected for each authentication table to the authentication device;
The authentication table includes a name indicating the candidate image group,
The authentication device determines a name indicating the image group set for the user to be included in the authentication table by applying an algorithm for sharing with the terminal device,
The terminal apparatus according to claim 1, wherein the selection accepting unit recognizes an image to be displayed by applying the algorithm to a name indicating an image group set for the user included in the authentication table.   A program that causes a computer to function as the authentication device according to claim 1.   A program that causes a computer to function as the terminal device according to claim 8.

Images