Authentication system, authentication server device, authentication method, and program

Abstract

Provided are: an authentication system that helps prevent impersonation (replay attacks) due to leakage of authentication query data in a biometric authentication system; and a corresponding authentication server device, authentication method, and program. An authentication system is provided that comprises: an authentication client device having a temporary conversion unit that receives a feature amount for receiving authentication and that converts the feature amount to authentication query data using a temporary conversion parameter; and an authentication server device having a registered feature amount data holding unit that holds registered feature amount data generated in response to reception of a feature amount for registration in a system, and a matching unit that performs matching on the basis of registered feature amount data and the authentication query data.

Description

Authentication system, authentication server device, authentication method and program

[0001] The present invention relates to an authentication system, an authentication server device, an authentication method, and a program.

[0002] In recent years, issues regarding biometric information registered in biometric authentication have come to light. This is because biometric authentication is personal information, and its leakage itself poses a privacy issue. Since biometric information cannot be discarded or updated even if it is leaked, if it is leaked, the security of all authentication systems that use the same biometric information will be lost.

[0003] On the other hand, standardization organizations such as the International Organization for Standardization (ISO) and the International Telecommunication Union Telecommunication Standardization Sector (ITU-T) also require, as standards for protecting biometric information, that even a server administrator cannot obtain the original biometric information and that protected biometric information can be invalidated.

[0004] Patent Literature 1 discloses a system for detecting fraudulent authentication data during matching in authentication using biometric information. In this system, enrollment data (template) to be registered in the system and authentication data to be matched are homomorphically encrypted at the time of enrollment and matching, respectively, and matching is performed while the data remains encrypted. This makes it possible to prevent the enrollment data and authentication data from being fraudulently used for authentication of other systems due to leakage of the authentication data or enrollment data due to theft or other reasons.

[0005] JP 2016-118984 A

[0006] The disclosures of the above prior art documents are incorporated herein by reference. The following analysis has been carried out by the present inventors.

[0007] As in Patent Document 1, it is possible to prevent the leakage of plaintext biometric features by encrypting the enrollment data (template) and authentication data, but it is possible to spoof using the leaked enrollment data and authentication data in the system from which they were leaked. In this regard, by introducing random numbers into the enrollment data that cancel each other out between the template and the query in calculations during matching, it is possible to make it impossible to perform matching calculations between enrollment data (templates), and it is possible to prevent spoofing by using enrollment data as authentication data.

[0008] However, if the authentication data (query) is leaked, the above countermeasures will allow spoofing because the data will be accepted as authentication unless the registration data and authentication data are re-encrypted. Since authentication data is likely to be stolen through phishing attacks, etc., countermeasures are recommended in light of the above circumstances.

[0009] An object of the present invention is to provide an authentication system, an authentication server device, an authentication method, and a program that contribute to preventing spoofing (replay attack) caused by leakage of authentication query data in a biometric authentication system.

[0010] According to a first aspect of the present invention and disclosure, there is provided an authentication system including: an authentication client device having a temporary conversion unit that receives features for authentication and converts the features using temporary conversion parameters to generate authentication query data; a registered feature data storage unit that stores registered feature data generated by receiving features to be registered in the system; and a matching unit that performs matching based on the registered feature data and the authentication query data.

[0011] According to a second aspect of the present invention and disclosure, there is provided an authentication server device having: a registered feature data storage unit that stores registered feature data generated by receiving features to be registered in a system; and a matching unit that performs matching based on authentication query data obtained by receiving features to be authenticated and converting the features using temporary conversion parameters, and the registered feature data.

[0012] According to a third aspect of the present invention and disclosure, there is provided an authentication method including the steps of receiving features for authentication and converting the features using temporary conversion parameters to generate authentication query data, receiving features to be registered in a system and storing the generated registered feature data, and performing matching based on the registered feature data and the authentication query data.

[0013] According to a fourth aspect of the present invention and disclosure, there is provided a program for causing a computer to execute a process of storing and retaining in a memory registered feature data that holds registered feature data generated by receiving features to be registered in a system, and matching the registered feature data with authentication query data obtained by converting the features for authentication using temporary conversion parameters.

[0014] According to each aspect of the present invention and disclosure, the present invention provides an authentication system, an authentication server device, an authentication method, and a program that contribute to preventing spoofing (replay attack) due to leakage of authentication query data in a biometric authentication system.

[0015] FIG. 1 is a schematic diagram showing an overview of processing in an authentication system according to an embodiment. FIG. 2 is a block diagram showing an example of the configuration of an authentication system according to an embodiment. FIG. 3 is a schematic diagram showing an overview of another processing in an authentication system according to an embodiment. FIG. 4 is a schematic diagram showing an overview of processing in an authentication system according to a first embodiment. FIG. 5 is a schematic diagram showing an overview of another processing in an authentication system according to the first embodiment. FIG. 6 is a block diagram showing an example of the configuration of an authentication system according to the first embodiment. FIG. 7 is a flowchart showing operation of the authentication system according to the first embodiment. FIG. 8 is a schematic diagram showing a hardware configuration of an authentication system according to the first embodiment. FIG. 9 is a schematic diagram showing an overview of processing in an authentication system according to a second embodiment. FIG. 10 is a schematic diagram showing an overview of another processing in an authentication system according to the second embodiment. FIG. 11 is a block diagram showing an example of the configuration of an authentication system according to the second embodiment. FIG. 12 is a diagram showing the flow of operation of the authentication system according to the second embodiment. FIG. 13 is a diagram showing the flow of operation of the authentication system according to the second embodiment.

[0016] [Overview of Processing of One Embodiment] First, an overview of processing of one embodiment will be described. Note that the drawing reference symbols attached to this overview are attached to each element for convenience as an example to facilitate understanding, and the description of this overview is not intended to be limiting in any way. Furthermore, the connection lines between blocks in each figure include both bidirectional and unidirectional. Unidirectional arrows are used to schematically indicate the flow of the main signal (data) and do not exclude bidirectionality. Furthermore, although not explicitly shown in the circuit diagrams, block diagrams, internal configuration diagrams, connection diagrams, etc. shown in this disclosure, input ports and output ports exist at the input and output ends of each connection line. The same applies to input / output interfaces.

[0017] 1 is a schematic diagram showing an overview of the processing of an authentication system according to an embodiment. As shown in this diagram, at the time of enrollment, biometric information is accepted by an enrollment client, and a feature x is extracted. This is then registered as enrollment data T in a registered feature database.

[0018] During authentication, the authentication client receives biometric information to be authenticated and extracts the feature value y. ｓ is generated. ｓ may be generated by the authentication server or may be generated by a separate server that generates keys. ｓ The transformation F is performed by the following formula. The matching data T' after the transformation F is calculated as follows: ｋｓ (y) is sent to the authentication server.

[0019] Here, it is assumed that the transformation F uses a method such as homomorphic encryption, which allows matching (calculation of similarity) while the data remains encrypted, but which has the property that matching fails if the key is different.

[0020] The authentication server compares the registered data with the matching data. ｓ Since all registered features to be matched are transformed by F ｋｓ Applying x to F ｋｓ Update to (x) and perform verification.

[0021] In this way, by generating a temporary conversion key during authentication and converting (encrypting) the verification data, the verification data converted with a different key each time a key is generated is sent to the authentication server. As a result, even if the verification data is leaked due to theft or other reasons, a different conversion key is generated and the verification data is converted. Therefore, since the converted key is different, even if the leaked verification data is sent to the authentication server again, verification is impossible and authentication fails.

[0022] [Configuration of an embodiment] Next, the configuration of an authentication system according to an embodiment will be described with reference to the drawings. Fig. 2 is a block diagram showing an example of the configuration of an authentication system according to an embodiment. As shown in this diagram, the authentication system according to an embodiment includes an authentication client device 10 and an authentication server device 11. The authentication client device 10 has a temporary conversion unit 12. The authentication server device 11 has a registered feature data storage unit 13 and a matching unit 14.

[0023] Although not shown, the authentication server device 11 may have a temporary conversion parameter generation unit that generates a temporary conversion key. The temporary conversion parameter generation unit may be included in a device different from the authentication client device 10 and the authentication server device 11.

[0024] The temporary conversion unit 12 receives a feature amount for authentication in the authentication client device 10, and converts the feature amount using a temporary conversion parameter to generate authentication query data.

[0025] The "authentication query data" is data to be compared with registered features. In this embodiment, this refers to data sent from the authentication client device 10 to the authentication server device 11 to be compared with registered features stored in the registered feature data storage unit 13 by the matching unit 14 of the authentication server device 11.

[0026] The registered feature data holding unit 13 holds registered feature data generated in the authentication server device 11 upon receiving features to be registered in the system.

[0027] The matching unit 14 performs matching based on the registered feature data and the authentication query data. In an authentication system according to an embodiment, the matching unit 14 matches the authentication query data with data converted based on the registered feature data.

[0028] [Outline of Another Process of an Embodiment] Fig. 3 is a schematic diagram showing an outline of another process of the authentication system according to an embodiment. As shown in this figure, ｓ is generated, and the feature data y to be authenticated is converted into F ｋｓ The conversion is performed by the following formula: The result of the conversion is the collation data T' = F ｋｓ (y) is sent to the authentication server, and before verification, the authentication server uses the temporary conversion key K ｓ By performing an inverse transformation using ｋｓ Calculate y from (y) and compare it with the registered feature x.

[0029] Here, "inverse transformation" means, for example, transforming feature data y into F ｋｓ Convert it to F ｋｓ (y), the conversion key K ｓ Using F ｋｓ It refers to obtaining y from (y).

[0030] That is, the matching unit 14 of the authentication server device 11 performs inverse conversion based on the authentication query data, and matches the resulting data y with the registered feature amount data x. ｋｓ It is necessary to use a conversion method that allows for inverse conversion.

[0031] In the process shown in the overview of the other process above, the conversion of features performed on the authentication server device 11 for matching only needs to be performed once on the matching data T′, making it possible to process faster than the form in which all registered features to be matched are converted as shown in the overview of the one embodiment above.

[0032] According to one embodiment of the authentication system, as described above, even if the biometric information to be authenticated is leaked during the authentication process, it is possible to prevent impersonation from passing the authentication of the system from which the information was leaked by generating a new temporary conversion key.

[0033] Specific embodiments will be described in more detail below with reference to the drawings. Note that the same components in each embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0034] [First Embodiment] In the authentication system of the above embodiment, when registering features in the system, the registered feature data is sent to the authentication server in plain text. Therefore, if the registered feature data (template) is leaked, there is a possibility that the features may be reused in other biometric authentication systems.

[0035] In the authentication system of this embodiment, at the time of registration, the registration client can convert (encrypt) the feature to be registered using the conversion key K. As a result, the feature to be registered at the time of registration is not sent in plain text from the registration client to the authentication server and stored in the registered feature database, but is stored in a converted (encrypted) state.

[0036] [Outline of the Processing of the First Embodiment] Fig. 4 is a schematic diagram showing an outline of the processing of the authentication system according to the first embodiment. As shown in this figure, a conversion key K is generated in advance, and the feature x acquired at the time of registration is converted using K to generate F. ｋ (x) and then register it in the registered feature database of the authentication server device. ｓ Each time a temporary conversion key K is generated, ｓ Update information Δ(K, K ｓ For this generation process, for example, a method of generating a re-encryption key for proxy re-encryption can be adopted. When verifying, the registered feature values ​​already registered are used as input to generate updated registered feature values ​​based on the generated update information, and verification is performed. That is, K ｓ Every time a feature is generated, all registered features are updated to Fｋ F from (x) ｋｓ The authentication client updates the temporary conversion key K ｓ The collation data T'=F ｋｓ (y) is sent to the authentication server for verification.

[0037] 5 is a schematic diagram showing an outline of another process of the authentication system according to the first embodiment. In another form of the authentication system according to the present embodiment, the authentication server ｓ Update information Δ(K ｓ , K), the verification data T'=F sent from the authentication client is ｋｓ The feature of (y) is updated to F ｋ It is possible to perform a matching process using (y).

[0038] [Configuration of First Embodiment] Next, the configuration of the authentication system of the first embodiment will be described with reference to the drawings. Fig. 6 is a block diagram showing an example of the configuration of the authentication system according to this embodiment. As shown in this diagram, the authentication system according to this embodiment includes an authentication client device 10 and an authentication server device 11. The authentication client device 10 has a temporary conversion unit 12. The authentication server device 11 has a registered feature data storage unit 13, a matching unit 14, and a first (second) update information generation unit 15 (16).

[0039] The temporary conversion unit 12 in the authentication client device 10 receives features for authentication and converts the features using temporary conversion parameters to generate authentication query data. The "features for authentication" are vector data extracted and digitized by applying predetermined image processing or the like to video captured by a device such as a camera. The "temporary conversion parameters" are parameters (encryption keys) used to perform a predetermined conversion F (encryption) on the features for authentication. In principle, it is desirable to generate new temporary conversion parameters when an authentication request is made by an authentication client. However, temporary conversion parameters do not necessarily have to be generated in response to each authentication request; they may be generated at any time, for example, when an external attack is suspected.

[0040] Furthermore, the "temporary conversion parameter" may be generated by a device different from the authentication client device 10 and the authentication server device 11, for example, a random number used to generate a password or a seed may be generated by a hardware device such as one used to generate one-time passwords, and then sent to the authentication client device 10, etc.

[0041] The registered feature data storage unit 13 receives features to be registered in the system and stores the generated registered feature data. "Features to be registered in the system" refers to information that serves as a template used during authentication. In the authentication system of this embodiment, as shown in FIGS. 4 and 5, the authentication server and the registration client use a common key K (predetermined transformation parameter) to convert the features to be registered in the system into converted registered feature data. This converted registered feature data is sent to the authentication server and stored in the registered feature database. This common key K is generated at least once when the authentication system operates, and when K is updated, all registered features stored in the authentication server must be overwritten and updated.

[0042] 4 and 5, the conversion process is performed at the registration client, and the converted registered feature data is sent to the authentication server. Although the above conversion process may be performed at the authentication server, it is preferable to perform the conversion at the registration client side, since the plaintext feature data will be transmitted over the communication path.

[0043] The first update information generating unit 15 generates first update information for updating data converted with predetermined conversion parameters to data converted with the temporary conversion parameters. ｓ Each time a temporary transformation key K is generated, the temporary transformation key K is generated. ｓ update information Δ(K, K) to a conversion key K consisting of predetermined conversion parameters ｓ ) to generate the

[0044] Here, the second update information generating unit 16 generates second update information for updating the data converted with the temporary conversion parameters to data converted with predetermined conversion parameters, in contrast to the first update information generating unit 15. At the time of authentication, a temporary conversion key K consisting of the temporary conversion parameters is generated. ｓ Each time a temporary transformation key K is generated, the temporary transformation key K is generated. ｓ to the conversion key K consisting of predetermined conversion parameters. ｓ , K).

[0045] The matching unit 14 performs matching based on the registered feature data and the authentication query data. In the case of a configuration including a first update information generation unit 15 (FIG. 4), update information Δ(K, K ｓ ) to F ｋ (x) to F ｋｓ (x), and the authentication query T' = F ｋｓ (y) is compared.

[0046] In the case of a configuration having the second update information generating unit 16 (FIG. 5), the update information Δ(K ｓ , K) to obtain T'=F ｋｓ (y) to F ｋ (y) and then F of the registered feature amount data ｋ Match with (x).

[0047] [System Operation] Fig. 7 is a flowchart showing the operation of the authentication system according to the first embodiment. Fig. 7 shows a series of operations until authentication is successful during system authentication. First, a temporary conversion key K ｓ Next, the biometric information of the subject of authentication is received and a feature is extracted (step S12). The extracted feature is then converted into a temporary conversion key K ｓ Convert it to F ｋｓ (y) (step S13). Next, the first update information Δ(K, K ｓ ) or the second update information Δ(K ｓ , K) is generated (step S14). Next, all the feature quantities F ｋ (x) (or authentication query data F ｋｓ(x) is updated (step S15).

[0048] Next, matching is performed (step S16). Specifically, the updated converted registered feature data F ｋｓ (x) and the authentication query data F ｋｓ If the similarity is within a predetermined acceptance standard, it is accepted (step S16: OK), and the temporary conversion key K ｓ If the result does not meet the acceptance criteria, the result is not accepted (step S16: NG), and the process returns to step S12 where biometric information is received and features are extracted.

[0049] [Hardware Configuration] The authentication system of this embodiment can be executed by an information processing device (computer), and includes an authentication client device 10 and an authentication server device 11 that constitute the system, with the configuration illustrated in Fig. 8. The authentication client device 10 and the authentication server device 11 include a CPU (Central Processing Unit) 101, a memory 102, an input / output interface 103, and a NIC (Network Interface Card) 104 as a communication means, which are interconnected by an internal bus 105.

[0050] However, the configuration shown in Fig. 8 is not intended to limit the hardware configuration of the authentication system. The authentication client device 10 and the authentication server device 11 may include hardware not shown, and may not be equipped with the input / output interface 103 as necessary. Furthermore, the number of CPUs and other components included in these devices is not intended to be limited to the example shown in Fig. 8; for example, the authentication client device 10 and the authentication server device 11 may include multiple CPUs.

[0051] The memory 102 is a RAM (Random Access Memory), a ROM (Read Only Memory), or an auxiliary storage device (such as a hard disk).

[0052] The input / output interface 103 is a means for interfacing with a display device and an input device (not shown). The display device is, for example, a liquid crystal display. The input device is, for example, a camera or sensor that receives biometric information, and a device that receives user operations such as a keyboard or mouse.

[0053] The functions of the authentication client device 10 and the authentication server device 11 are realized by a group of programs (processing modules) stored in memory 102, such as a temporary conversion program, a first (second) update information generation program, a matching program, and the like, and a group of data, such as parameters, used by each program. The processing modules are realized, for example, by the CPU 101 executing each program stored in memory 102. The programs can be updated by downloading them over a network or using a storage medium on which the programs are stored. Furthermore, the processing modules may be realized by semiconductor chips. That is, it is sufficient to have some means for executing the functions performed by the processing modules using some kind of hardware and / or software.

[0054] [Hardware Operation] When the authentication system starts operation, the temporary conversion program is called from the memory 102 in the authentication client device 10 and is put into an execution state by the CPU 101. The program generates and acquires the temporary conversion parameter K ｓ The input / output interface 103 converts (encrypts) the feature extracted from the acquired biometric information y using the conversion key F. ｋｓ (y) is sent to the authentication server device 11 via the NIC 104 or the like.

[0055] The authentication server device 11 stores the converted registered feature F converted by a predetermined conversion parameter K in the memory 102. ｋ (x) is stored in the memory 102. Here, the first (second) update information generation program is called from the memory 102 and is put into execution state on the CPU 101. This program is capable of converting data that has been converted with a key based on two different types of conversion parameters by updating. The first update information generation program converts the update information Δ(K, K ｓThe second update information generation program generates update information Δ(K ｓ , K).

[0056] Next, the matching program is called by the memory 102 and executed by the CPU 101. The program updates the transformed feature quantity using the update information Δ and performs matching. Specifically, the update information Δ(K, K ｓ ) to the converted registered feature F stored in the memory 102. ｋ (x) and the temporary transformation parameter K ｓ Feature F using ｋｓ (x) and update it to the same parameter K ｓ F from the authentication client device, converted using ｋｓ (y) and F ｋｓ (x) and F ｋｓ The distance between (y) is calculated to determine the similarity. If the distance between the two is equal to or less than a predetermined value, the result is accepted, and if it is greater than the predetermined value, the result is rejected.

[0057] Similarly, the update information Δ(K ｓ , K), the matching program uses the feature F ｋｓ (y) is calculated by F using the update information Δ. ｋ (y), and the converted registered feature F stored in the memory 102 ｋ The specific process of the matching is described above, so the details are omitted here.

[0058] [Explanation of Effects] As described above, the authentication system of this embodiment makes it possible to conceal registered features by conversion, and does not need to rewrite the registered feature database for matching even when a new temporary conversion key is generated, and matching is possible by updating the registered features (after conversion) using update information at the time of matching. Furthermore, when generating the temporary conversion key, it is not necessary to distribute the conversion key to all authentication clients, and it is sufficient to distribute it only to the authentication client and the authentication server that request authentication, which has the effect of reducing key distribution costs and improving security.

[0059] Furthermore, as described in [Outline of another process of the first embodiment], by using the update information to update the key that converts the authentication query data during matching (temporary conversion parameter → predetermined conversion parameter), data updating can be completed only once per authentication. Therefore, as described in [Configuration of the first embodiment], there is an advantageous effect that processing can be executed faster than updating all of the converted registered features with the update information.

[0060] [Overview of the Processing of the Second Embodiment] As described in the above embodiment, by using the update information Δ of the conversion key (conversion parameter), the temporary conversion key K ｓ 3 and 4, a predetermined conversion key (conversion parameter) K and the registered feature data converted by the conversion key are both stored in the same authentication server device, and there remains a concern that if the authentication server device is attacked, the registered feature data will be decrypted by K and plaintext features will be leaked.

[0061] In this embodiment, an authentication system is provided that has the same effects as the above-described embodiments, but does not use K, which is a predetermined conversion parameter, in the authentication server.

[0062] 9 is a schematic diagram showing an overview of the processing of the authentication system according to the second embodiment. As shown in this diagram, a predetermined conversion key K is first delivered to a registration client at the time of registration, and the feature x to be registered in the system is converted to the converted registered feature data F ｋ (x) is stored in the registered feature database of the authentication server.

[0063] During authentication, a temporary conversion key K ｓ is generated and sent to the authentication client device, the conversion key K and the temporary conversion key K ｓ and the composite transformation key K ｓ During authentication, the authentication client device generates a composite transformation key K ｓ Convert with K and set T' = F as authentication query (matching) data ｛ｋｓ・ｋ｝(y) = F ｋｓ (F ｋ (y)) is sent to the authentication server as an authentication query. ｓ and obtain the registered transformed registered feature data F ｋ (x) to K ｓ Reconvert it with F ｋｓ (F ｋ (x)) and the authentication query T'=F ｋｓ (F ｋ (y)) and check.

[0064] [Outline of another process of the second embodiment] Fig. 10 is a schematic diagram showing an outline of another process of the authentication system according to the second embodiment. As shown in this figure, in the process of Fig. 9, the converted registered feature data is re-converted and compared with the synthetically converted authentication query (matching) data. In the outline of the other process, the synthetic transformation key K ｓ ・Feature T' converted by K = F ｛ｋｓ・ｋ｝ (y) = F ｋｓ (F ｋ (y)) is invertible, and the converted authentication query (verification) data is converted into F ｋ (y) is obtained, and the registered feature F ｋ Match with (x).

[0065] [Configuration of Second Embodiment] Next, the configuration of an authentication system according to the second embodiment will be described with reference to the drawings. FIG. 11 is a block diagram showing an example of the configuration of an authentication system according to this embodiment. As shown in this diagram, the authentication system according to this embodiment includes an authentication client device 10 and an authentication server device 11. The authentication client device 10 has a temporary conversion unit 12 and a composite conversion parameter generation unit 17. The authentication server device 11 has a registered feature data storage unit 13 and a matching unit 14. A feature of this embodiment is that the authentication client device 10 further includes the composite conversion parameter generation unit 17.

[0066] The composite transformation parameter generating unit 17 performs transformation using a predetermined parameter (K) and transformation using the temporary transformation parameter (K ｓThe generated composite transformation parameters are sent to the temporary transformation unit 12.

[0067] In this embodiment, the temporary conversion unit 12 receives the composite conversion parameters from the composite conversion parameter generation unit 17, converts the feature amount for authentication, and generates composite converted authentication query data.

[0068] In this embodiment, the matching unit 14 in the authentication server device 11 converts the converted registered feature data again using the temporary conversion parameters, and performs matching with the synthesized and converted authentication query data.

[0069] [Another Configuration of the Second Embodiment] In this embodiment, in another configuration of the second embodiment corresponding to [Outline of Another Process of the Second Embodiment], based on the configuration of the second embodiment, the matching unit 14 inversely transforms the synthesized transformed authentication query data using temporary transformation parameters, and performs matching with the transformed registered feature data.

[0070] [System Operation] Fig. 12 is a diagram showing the flow of operation of the authentication system according to the second embodiment. In particular, this diagram shows the flow of authentication during the authentication system of this embodiment. As shown in this diagram, first, in the registration stage, a predetermined transformation parameter K is delivered to the authentication client device. Furthermore, in the authentication server device, a transformed registered feature F, which is a registered feature transformed by the predetermined transformation parameter K, is delivered to the authentication client device. ｋ (x) is stored.

[0071] When an authentication request is made from the authentication client device, a temporary conversion parameter K ｓ is generated and delivered to the authentication client device and the authentication server device. ｓ may be generated by the authentication server device or by an independent temporary conversion parameter generating device. ｓ On the other hand, in the authentication server device, a temporary conversion parameter K ｓ Using the above, the converted registered feature F ｋ (x) to Kｓ The re-transformation is performed by the following formula, and the registered feature value F ｋｓ (F ｋ (x)) is calculated.

[0072] The authentication client device receives the biometric information and extracts the authentication feature y. ｓ ・Conversion process is performed using K, and F ｛ｋｓ・ｋ｝ (y) = F ｋｓ (F ｋ This is sent as an authentication query (verification data) to the authentication server device, which then executes the verification process.

[0073] 13 is a diagram showing another operation flow of the authentication system according to the second embodiment. The difference from the above is that after an authentication query (matching data) is sent from the authentication client device, the authentication server device converts the temporary conversion parameter K ｓ After the inverse transformation (F ｋｓ (F ｋ (y)) → F ｋ (y)) with the feature F ｋ (y) is obtained, and the converted registered feature F ｋ A matching process with (x) is performed.

[0074] [Explanation of Effects] The authentication system of this embodiment uses the temporary conversion parameter K ｓ By performing temporary conversion using a composite conversion parameter of the predetermined conversion parameter K, the authentication server device does not need to perform processing using the predetermined conversion parameter K. The conversion parameter K and the converted registered feature amount data F are stored in memory. ｋ (x) will no longer be stored, and the authentication server device will be attacked, and K and F ｋ (x) are stolen, and F ｋ (x) is decrypted, and the risk of the plaintext feature x being leaked is reduced.

[0075] [Third Embodiment] In the authentication systems of the first and second embodiments, if the authentication query and the corresponding temporary conversion key are leaked at the same time, spoofing can be performed by using both pieces of information. For example, if the authentication query T′=F ｋｓ (y) and the temporary conversion key K ｓ If the temporary conversion key K is leaked, the temporary conversion key K is transmitted from the authentication server device in another authentication process. ｔ In contrast, K ｓ and K. ｔ From the update information Δ(K ｓ , K ｔ ) can be calculated. ｓ， K ｔ ) to find T' = F ｋｓ (y) to F ｋｔ By updating the feature value y to (y) and sending it as an authentication query, the matching process will be successful. Furthermore, if the conversion method is easy to calculate the inverse conversion, the feature value y itself can be restored from the authentication query and the temporary conversion key.

[0076] Therefore, the authentication system of this embodiment is based on the authentication systems of the first and second embodiments, and uses secret information shared in advance between the authentication client device and the authentication server device to generate a temporary conversion key K ｓ It is possible to prevent spoofing even if the authentication query and the password are leaked at the same time.

[0077] In the configuration described above in [Overview of the processing of the first embodiment], the authentication client device receives the temporary conversion key K ｓ and a separate temporary conversion key K ｕ and generate an authentication query T' = F ｋｕ The authentication server also sends K ｕ and generate Δ(K,K ｕ ) and calculate the registered feature F ｋ (x) to K ｕ F converted by ｋｕ Update to (x) and verify. K ｓ and T' = F ｋｕ Since (y) has a different conversion key, even if both are leaked at the same time, they cannot be used for impersonation.

[0078] In the configuration described above in [Outline of another process of the first embodiment], the update information Δ(K ｕ , K), and the matching query F ｋｕ (y) to Δ(K ｕ , K) in F ｋ Update to (y) and verify.

[0079] In the configuration described above in [Overview of the Processing of the Second Embodiment], the authentication client device receives the temporary conversion key K ｓ and another temporary conversion key K ｕ and generate an authentication query T' = F ｋｕ (F ｋ The authentication server also sends K ｕ and generate the registered feature F ｋ (x) to K ｕ F retransformed with ｋｕ (F ｋ (x)) and verify. ｓ and T' = F ｋｕ (F ｋ (y)) have different conversion keys, so even if they are both leaked at the same time, they cannot be used for impersonation.

[0080] In the configuration described above in [Outline of another process of the second embodiment], the authentication server device ｋｕ (F ｋ (y)) to K ｕ Inverse transformation is performed with F ｋ Update to (y) and verify.

[0081] In the above embodiment, the shared secret information may be other than the temporary conversion key, such as the cancelable conversion key K used at the time of registration, or a "master parameter" previously shared between the authentication client and the authentication server. ｕ Regarding the method of generating F, the shared secret information is a predetermined conversion key K. ｋｕ (*) = F ｋ (F ｋｓ (*)) ｕ The shared secret information is the master parameter param, and the input random number seed for the key generation process is (K ｓ ||param) is given as the output. ｕ One possible method is to

[0082] [Fourth Embodiment] The authentication system according to the first embodiment requires the authentication server to always store a predetermined re-key K, which poses a security concern. The authentication system according to this embodiment can prevent spoofing attacks that use the authentication query while storing only a portion of the predetermined re-key K (for example, only the latter half) on the authentication server.

[0083] In the authentication system of the fourth embodiment, the authentication server device has a challenge generation unit (not shown) that generates a challenge and transmits it to the authentication client device, and a verification unit (not shown) that receives a response and performs verification using temporary conversion parameters, and the authentication client device has a temporary conversion unit that further converts the challenge using the temporary conversion parameters and transmits the response to the verification unit of the authentication server device, and the verification unit of the authentication server device performs verification using part of the predetermined conversion parameters.

[0084] The operation of the authentication system of this embodiment is as follows: first, the authentication server generates a random number sequence to be used when temporarily converting the authentication query and sends it to the authentication client as a challenge. Meanwhile, the authentication server device converts the sent random number sequence using a portion of a predetermined conversion key K (for example, only the latter half) and stores it as check data. Upon receiving the authentication query, in addition to the usual verification process, it checks whether the values ​​of the check data portion match, and if there is a mismatch at even one point, the authentication is rejected.

[0085] In the authentication system of this embodiment, the authentication server device only needs to store a portion of the predetermined conversion key K, which can reduce security concerns such as leakage due to attacks.

[0086] Some or all of the above-described embodiments can also be described as in the following supplementary notes. However, the following supplementary notes are merely examples of the present invention, and the present invention is not limited to such cases. [Supplementary Note 1] As in the authentication system according to the first aspect described above. [Supplementary Note 2] Preferably, the authentication system of Supplementary Note 1, in which the matching unit of the authentication server device transforms registered feature data using temporary transformation parameters and performs matching. [Supplementary Note 3] Preferably, the authentication system of Supplementary Note 1, in which the matching unit of the authentication server device inversely transforms authentication query data using temporary transformation parameters and performs matching. [Supplementary Note 4] Preferably, the authentication system of Supplementary Note 1, in which, when registering features to be registered in the system, the registered feature data storage unit of the authentication server device stores transformed registered feature data obtained by converting the features using predetermined transformation parameters and registering them, and the matching unit performs matching between the transformed registered feature data and the authentication query data. [Supplementary Note 5] The authentication server device further has a first update information generation unit that generates first update information for updating data converted with predetermined conversion parameters to data converted with temporary conversion parameters, and the matching unit updates the converted registered feature data using the first update information and performs matching with the authentication query data, preferably the authentication system of Supplementary Note 4. [Supplementary Note 6] The authentication server device further has a second update information generation unit that generates second update information for updating data converted with temporary conversion parameters to data converted with predetermined conversion parameters, and the matching unit updates the authentication query data using the second update information and performs matching with the converted registered feature data, preferably the authentication system of Supplementary Note 4. [Supplementary Note 7] Preferably, the authentication system according to Supplementary Note 4, wherein the authentication client device includes a composite transformation parameter generation unit that generates composite transformation parameters for performing a transformation that combines a transformation using predetermined parameters and a transformation using temporary transformation parameters, the temporary transformation unit converts features for authentication using the composite transformation parameters to generate composite-converted authentication query data, and the authentication server device includes a matching unit that converts the converted registered feature data again using the temporary transformation parameters and performs matching with the composite-converted authentication query data.[Supplementary Note 8] Preferably, the authentication system of Supplementary Note 4 is characterized in that the authentication client device includes a composite transformation parameter generation unit that generates composite transformation parameters for performing a transformation that combines a transformation using predetermined parameters and a transformation using temporary transformation parameters, the temporary transformation unit transforms the features for authentication using the composite transformation parameters to generate composite-transformed authentication query data, and the authentication server device includes a matching unit that inversely transforms the composite-transformed authentication query data using the temporary transformation parameters to match it with transformed registered feature data. [Supplementary Note 9] Preferably, the authentication system of any one of Supplements 5 to 8 is characterized in that the authentication client device includes a first secret information temporary transformation parameter generation unit that generates secret information temporary transformation parameters using secret information shared with the authentication server device and the temporary transformation parameters, the temporary transformation unit transforms the features for authentication using the secret information temporary transformation parameters instead of the temporary transformation parameters to generate secret information temporarily transformed authentication query data, and the authentication server device includes a second secret information temporary transformation parameter generation unit that generates secret information temporary transformation parameters using secret information shared with the authentication client device and the temporary transformation parameters. [Supplementary Note 10] Preferably, the authentication system of Supplementary Note 9, wherein the matching unit of the authentication server device converts the converted registered feature data using the secret information temporary conversion parameter and performs matching with the secret information temporarily converted authentication query data. [Supplementary Note 11] Preferably, the authentication system of Supplementary Note 9, wherein the matching unit of the authentication server device converts the secret information temporarily converted authentication query data using the secret information temporary conversion parameter and performs matching with the registered feature data. [Supplementary Note 12] Preferably, the authentication system of Supplementary Note 5 or 6, wherein the authentication server device has a challenge generation unit that generates a challenge and transmits it to the authentication client device, and a verification unit that receives a response and performs verification using the temporary conversion parameter, and the authentication client device has a temporary conversion unit that further converts the challenge using the temporary conversion parameter and transmits it as a response to the verification unit of the authentication server device. [Supplementary Note 13] Preferably, the authentication system of Supplementary Note 12, wherein the authentication server device has a verification unit that performs verification using part of the predetermined conversion parameter. [Supplementary Note 14] As in the authentication server device according to the second aspect described above.[Supplementary Note 15] As in the authentication method according to the third aspect described above. [Supplementary Note 16] As in the program according to the fourth aspect described above.

[0087] The disclosures of the above-cited patent documents and other documents are incorporated herein by reference. Modifications and adjustments of the embodiments are possible within the scope of the entire disclosure of the present invention (including the claims), and further based on the basic technical concepts thereof. Furthermore, various combinations and selections (including partial deletions) of various disclosed elements (including elements of each claim, each embodiment, each element of each embodiment, each element of each drawing, etc.) are possible within the scope of the entire disclosure of the present invention. In other words, the present invention naturally includes various modifications and alterations that would be possible by a person skilled in the art in accordance with the entire disclosure and technical concepts, including the claims. In particular, with regard to the numerical ranges described herein, any numerical value or subrange included within the range should be construed as being specifically described, even if not otherwise specified.

[0088] 10: Authentication client device 11: Authentication server device 12: Temporary conversion unit 13: Registered feature amount data storage unit 14: Matching unit 15: First update information generation unit 16: Second update information generation unit 17: Synthesis conversion parameter generation unit 101: CPU 102: Memory 103: Input / output interface 104: NIC 105: Internal bus

Claims

1. An authentication system including: an authentication client device having a temporary conversion unit that receives features for authentication and converts the features using temporary conversion parameters to generate authentication query data; an authentication server device having: a registered feature data storage unit that receives features to be registered in the system and stores registered feature data generated; and a matching unit that performs matching based on the registered feature data and the authentication query data.

2. The authentication system according to claim 1, wherein the authentication server device is configured such that the matching unit converts the registered feature data using the temporary conversion parameters and performs matching.

3. The authentication system according to claim 1, wherein in the authentication server device, the matching unit performs matching by inversely converting the authentication query data using the temporary conversion parameter.

4. The authentication system of claim 1, wherein the authentication server device stores converted registered feature data obtained by the registered feature data storage unit, when registering features to be registered in the system, by converting the features using predetermined conversion parameters, and the matching unit matches the converted registered feature data with the authentication query data.

5. The authentication system of claim 4, wherein the authentication server device further comprises a first update information generation unit that generates first update information for updating the data converted using the predetermined conversion parameters to data converted using the temporary conversion parameters, and the matching unit updates the converted registered feature data using the first update information and performs matching with the authentication query data.

6. The authentication system of claim 4, wherein the authentication server device further comprises a second update information generation unit that generates second update information for updating the data converted using the temporary conversion parameters to data converted using the predetermined conversion parameters, and the matching unit updates the authentication query data using the second update information and performs matching with the converted registered feature data.

7. The authentication system of claim 4, wherein the authentication client device has a composite transformation parameter generation unit that generates a composite transformation parameter for performing a transformation that combines a transformation using the predetermined parameter and a transformation using the temporary transformation parameter, wherein the temporary transformation unit converts the feature data for authentication using the composite transformation parameter to generate composite transformed authentication query data, and wherein the authentication server device has a matching unit that converts the transformed registered feature data again using the temporary transformation parameter and performs matching with the composite transformed authentication query data.

8. The authentication system of claim 4, wherein the authentication client device has a composite transformation parameter generation unit that generates a composite transformation parameter for performing a transformation that combines a transformation using the predetermined parameter and a transformation using the temporary transformation parameter, wherein the temporary transformation unit converts the feature for authentication using the composite transformation parameter to generate composite transformed authentication query data, and wherein the authentication server device has a matching unit that inversely transforms the composite transformed authentication query data using the temporary transformation parameter and performs matching with the transformed registered feature data.

9. An authentication system according to any one of claims 5 to 8, wherein the authentication client device comprises: a first secret information temporary conversion parameter generation unit that generates a secret information temporary conversion parameter using secret information shared with the authentication server device and the temporary conversion parameter; the temporary conversion unit converts the feature for authentication using the secret information temporary conversion parameter instead of the temporary conversion parameter to generate authentication query data after temporary conversion of secret information; and the authentication server device comprises: a second secret information temporary conversion parameter generation unit that generates the secret information temporary conversion parameter using secret information shared with the authentication client device and the temporary conversion parameter.

10. The authentication system of claim 9, wherein the authentication server device has a matching unit that converts the converted registered feature data using the secret information temporary conversion parameter and performs matching with the secret information temporarily converted authentication query data.

11. The authentication system according to claim 9, wherein the authentication server device has a matching unit that converts the authentication query data after temporary secret information conversion using the temporary secret information conversion parameter and performs matching with the registered feature amount data.

12. An authentication system according to claim 5 or 6, wherein the authentication server device has a challenge generation unit that generates a challenge and sends it to the authentication client device, and a verification unit that receives a response and verifies it using the temporary conversion parameters, and the authentication client device has the temporary conversion unit that further converts the challenge using the temporary conversion parameters and sends it as the response to the verification unit of the authentication server device.

13. The authentication system according to claim 12, wherein in the authentication server device, the verification unit performs verification using a part of the predetermined conversion parameters.

14. An authentication method including the steps of: receiving features for authentication and transforming the features using temporary transformation parameters to generate authentication query data; receiving features to be registered in the system and storing the generated registered feature data; and performing matching based on the registered feature data and the authentication query data.

15. An authentication server device having: a registered feature data storage unit that receives features to be registered in a system and stores registered feature data generated by the reception of the features; and a matching unit that receives features to be authenticated and converts the features using temporary conversion parameters to perform matching based on the registered feature data and authentication query data.

16. A program for causing a computer to execute the following process: storing in memory registered feature data that holds registered feature data generated by accepting features to be registered in the system; and matching the registered feature data with authentication query data obtained by converting the features for authentication using temporary conversion parameters.