JP6426520B2 - Encryption key management system and encryption key management method - Google Patents

Description

The present embodiment relates to an encryption key management system and an encryption key management method.

  In recent years, not only can protect information by user authentication about information that you want to conceal such as personal information (hereinafter referred to as confidential information), you can copy database or extract HDD (spoofing of secondary storage) or theft of backup media ( There is a need for a system that can protect confidential information even when information stored in secondary storage or tertiary storage is spoofed, such as tertiary storage misrepresentation).

  In response to such a request, there is known a system in which confidential information is encrypted and stored on the data server side, and the encryption key used for the encryption is stored on the application server side. If the information in question is spoofed, it becomes possible to decrypt the encrypted confidential information with the encryption key.

  Therefore, a method of storing in the system an encryption key (key hash) created from information (for example, a password) which can be known only by the user who uses the system is effective.

JP 2012-79231 A

  However, in the prior art, when the user changes the password in parallel while using the system after authentication, a new encryption key (hereinafter referred to as an old encryption key) created at the time of authentication and a password change are newly made. The contents of the created encryption key (hereinafter referred to as a new encryption key) will be different. As a result, if it is attempted to decrypt the information (protected data) concealed using the old encryption key with the new encryption key, in order to avoid the error at the time of decryption, the new authentication is performed after the re-authentication. There is a problem that it is necessary to create an encryption key, resulting in a decrease in work efficiency.

  Therefore, in view of the above-described problems of the prior art, the present invention changes the password without executing re-authentication when there is a change in the password in parallel while the authenticated user is using the system. The protection data encrypted by the previous old encryption key is continuously decodable.

  The encryption key management system according to the present embodiment requires a server that encrypts and decrypts protected data with a master key, and requests the server for user authentication via a network based on input information including a user ID and a password. An encryption key management system comprising: a user terminal requesting encryption and decryption of the protected data, wherein the server includes: a revision of the password hash calculated from the user ID, the password, and the password hash User information storage means for storing associated user information, the user ID, an encrypted key obtained by encrypting the master key with the key hash calculated from the password, and a key for storing key information associating the revision Information storage means, the input information and the user information; When the user authentication is completed by collation, an authentication ID is issued, and authentication information in which the user ID, the revision, the key hash, and the authentication time are associated with the authentication ID is generated and held. Authentication means, and when changing the password to a new password, the encrypted key obtained from the key information using the combination of the user ID and the revision included in the authentication information as a search key is the key The master key is obtained by decryption using a hash, and a new encrypted key is created based on the new password and the master key, the user ID, a new revision related to the new password, and In a state where new key information associated with a new encrypted key coexists with other key information related to the same user ID And having a key re-encryption unit for storing the key information storing means.

FIG. 1 is a block diagram showing an example of the overall configuration of a cryptographic key management system according to an embodiment. The figure which shows an example of authentication information. The figure which shows an example of user information. The figure which shows an example of key information. The figure which shows an example of protection data. Explanatory drawing of a user authentication process. Explanatory drawing of protection data registration processing. Explanatory drawing of protection data acquisition processing. Explanatory drawing of the password change process by the request | requirement of the same user. Explanatory drawing of the password change process by the other user's request. Explanatory drawing of a certification | authentication maintenance process. Explanatory drawing of a key information cleaning process. Explanatory drawing of authentication information deletion process. FIG. 7 is a sequence diagram showing an example of an operation at the time of password change in the encryption key management system according to an embodiment.

  Hereinafter, the encryption key management system according to the present embodiment will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an example of the entire configuration of a cryptographic key management system according to an embodiment. As shown in the figure, the encryption key management system is configured by connecting a user terminal 1, an authentication server 2, a user DB 3, an application server 4 and a data server 5 via a communication network NW.

  Each device includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), an input device, a display device, a large-capacity storage device such as a hard disk drive (HDD), and a communication device. The computer is configured, and the number is arbitrary. In addition, although the present system includes a plurality of servers, it may be connected to one or more servers after being appropriately integrated or dispersed.

  The user terminal 1 is an information terminal such as a personal computer used by a user for data editing work, and includes an authentication request unit 11, a data reference request unit 12, a data registration request unit 13, and a password change request unit 14.

  The authentication request means 11 transmits input information including a user ID and a password to the authentication server 2, and requests user authentication processing. After completion of user authentication, the data reference request means 12 connects to the application server 4 based on the authentication information, and requests reference processing of protection data managed in the data server 5.

  The data registration request means 13 connects to the application server 4 based on the authentication information, and requests the data server 5 to perform protection data registration processing. The password change request means 14 requests the authentication server 2 to change the existing password into a new password.

  The authentication server 2 is a server computer that executes authentication processing, and includes an authentication information providing unit 22, a password changing unit 23, an authentication maintaining unit 24, an authentication information checking unit 25, a key cleaning unit 26, and an authentication deleting unit 27. There is.

  The authentication means 21 performs user authentication by collating the new password hash calculated from the user ID and password contained in the input information with the user information stored in the user DB 3. When the user authentication is completed (successful), the authentication means 21 issues a unique authentication ID, and for this authentication ID, a revision which is a user ID unique to each user, a password generation number, a key hash And generate authentication information associated with authentication time, and hold it. The key hash is calculated using a predetermined hash function.

  FIG. 2 is a diagram showing an example of authentication information. Here, it is shown that the authentication information is information in which the user ID, the revision, the key hash, and the time of the last access to the authentication information are associated for each authentication ID. The key hash is calculated using the hash function Hk (x) for the key. The plaintext Pn_m (n: user number, m: revision number) of the password is used as x of the hash function Hk (x).

When receiving the authentication ID from the application server 4, the authentication information providing unit 22 provides the application server 4 with the authentication information of the authentication ID.
When there is a password change request from the user terminal 1, the password change means 23 transmits new user information including the user ID, the password hash calculated from the new password, and the revision of the password to the user DB 3, Update information Also, the password changing means 23 transmits the user ID, the revision and key hash of the current password, and the key hash based on the new password to the user DB 3 and registers new key information.

When the authentication maintenance means 24 receives the authentication ID of the authentication information held by the application server 4, it searches the authentication information held in the authentication server 2 based on the received authentication ID, and the authentication information whose authentication ID matches Maintain authentication by updating the time of day to the current time.
The authentication information confirmation means 25 confirms whether or not the authentication information corresponding to the combination information of the user ID and the revision received from the key cleaning means 26 exists in the authentication server 2, and the confirmation result for each combination is the key cleaning means Send to 26

The key cleaning unit 26 extracts combination information of the user ID and the revision with reference to the key information stored in the user DB 3 and periodically transmits the combination information to the authentication information confirmation unit 25. Then, when there is key information that does not exist in the authentication server 2 as the response information from the authentication information confirmation unit 25, the key cleaning unit 26 deletes the key information.
The authentication deletion means 27 periodically compares the time of the authentication information held on the authentication server 2 side with the current time, and deletes the authentication information for which a predetermined time-out time has elapsed.

  The user DB 3 is a database for storing information necessary for the authentication process in the authentication server 2 and the data write / read process in the data server 5, and the user information storage means 31, key information storage means 32, key re-encryption means 33. have.

  The user information storage unit 31 stores user information identifying a user, password hash, and user information associated with a revision. FIG. 3 is a diagram showing an example of user information. The password hash is calculated using the password hash function Hp (x). As x of the hash function Hp (x), the plaintext Pn_m (n: user number, m: revision number) of the password is used.

  The key information storage means 32 stores key information associated with the user ID, the revision, and the encrypted key. FIG. 4 is a diagram showing an example of key information. The encrypted key is calculated using the function Ck (x, y) for the key. Here, a key hash is used for x of the function Ck (x, y), and a master key (common key) M is used for y.

  The key re-encryption means 33 uses the combination of the user ID and the revision included in the authentication information as the search key as the search key when changing the password input in the user authentication to a new password, as an encrypted key Decrypts with a key hash included in the authentication information to obtain a master key, and creates a new encrypted key based on the new password and the master key, a user ID, a new revision related to the new password, The new key information associated with the new encrypted key is stored in the key information storage unit 32 in the state of coexistence with other key information related to the same user ID.

  Also, when the key re-encryption means 33 requests from the user terminal 1 side a password change request to associate another user ID and another password different from that at the time of authentication with respect to the common authentication ID The key hash is generated, the user ID associated with the common authentication ID is acquired from the authentication information held in the authentication server 2, the key hash is acquired, the master key is decrypted, and another key is generated using this master key. The key information storage means 32 stores other key information obtained by combining the hash with another encrypted key, another user ID, and another password revision.

  The application server 4 is a server computer that provides a service to the user terminal 1 by executing various applications (not shown), and the data registration unit 41, the authentication information reference unit 42, the data reference unit 43, and the authentication maintenance request Means 44 and authentication deletion means 45 are provided.

The data registration means 41 registers received data in the data server 5 when there is a data registration request from the authenticated user terminal 1.
The authentication information reference unit 42 requests the authentication server 2 to refer to the authentication information when the authentication information is required as the application is executed.

When there is a data reference request from the authenticated user terminal 1, the data reference unit 43 acquires protection data from the data server 5 and sends it back to the user terminal 1.
The authentication maintenance request means 44 periodically transmits the authentication ID of the authentication information held on the application server 4 side to the authentication server 2, and requests authentication maintenance. The authentication deletion means 45 periodically compares the time of the authentication information held on the application server 4 side with the current time, and deletes the authentication information for which a predetermined timeout time has elapsed.

  The data server 5 is a server computer that manages protected data, and includes a protected data storage unit 51, a data writing unit 52, and a data reading unit 53.

  The protected data storage unit 51 encrypts protected data for which a registration request has been made from the user terminal 1 via the application server 4 and stores the encrypted protected data for each data ID. FIG. 5 is a diagram showing an example of protection data. Here, the protection data is encrypted in association with the data ID specifying the protection data for each column by the data function Cd (x, y) and stored. Here, x of the function Cd (x, y) is a master key M, and y is a plaintext (n: data number, m: column) of Dn_m data.

  The data writing means 52 encrypts the data acquired from the user terminal 1 via the application server 4 with the master key decrypted from the key information, and writes it in the protected data storage means 51 as protected data. The data reading means 53 reads the encrypted protected data from the protected data storage means 51, decrypts it with the master key decrypted from the encrypted key of the key information, and sends it to the application server 4.

Subsequently, the flow of processing between devices constituting the encryption key management system will be specifically described.
(1) User Authentication Process FIG. 6 is an explanatory diagram of the user authentication process. As shown in the figure, when the user inputs the user ID [U1] and the password [P1_1] using the authentication request means 11 of the user terminal 1, the user terminal 1 sends the authentication means 21 of the authentication server 2 to the authentication means 21. On the other hand, authentication is requested together with the user ID [U1] and the password [P1_1].

  The authentication unit 21 authenticates the user by matching the password hash [Hp (P1_1)] generated from the user ID [U1] and the password [P1_1] with the user information held by the user DB 3. The user information has, in addition to the user ID [U1] and the password hash [Hp (P1_1)], the revision [R1] indicating the number of times of updating of the password hash.

  When the authentication is successful, the authentication unit 21 adds the authentication ID [A1], the user ID [U1], the revision [R1], the authentication time [T1], and the key hash [Hk generated from the password [P1_1] to be assigned for each authentication process. The pair of (P1_1)] is newly added to the authentication information, and the authentication ID [A1] is returned to the authentication request means 11.

(2) Protected Data Registration Process FIG. 7 is an explanatory diagram of the protected data registration process. As shown in the figure, the user inputs the registration data key [D1] and the registration data values [D1_1] and [D1_2] together with the authentication ID [A1] using the data registration request means 13 of the user terminal 1 Then, the user terminal 1 requests the data registration unit 41 of the application server 4 for data registration together with the authentication ID [A1], the registration data key [D2], and the registration data values [D2_1] and [D2_2].

  The data registration means 41 gives the authentication ID [A1] to the authentication information reference means 42, whereby the user ID [U1] is linked to the authentication ID [A1] via the authentication information provision means 22 of the authentication server 2. Get the revision [R1], key hash [Hk (P1_1)], and add them to the authentication information in the application server 4 anew.

  Next, the data registration unit 41 registers the user ID [U1], the revision [R1], the key hash [Hk (P1_1)], the registered data key [D2], and the registration with respect to the data writing unit 52 of the data server 5. Given data values [D2_1], [D2_2], request registration of protected data.

  The data writing means 52 acquires an encrypted key [Ck (Hk (P1_1), M)] associated with the user ID [U1] and the revision [R1] from among the key information held by the user DB 3 Decrypt the master key [M] using the key hash [Hk (P1_1)].

  Next, the data writing means 52 encrypts the registered data values [D2_1] and [D2_2] using the master key [M], and respectively encrypts [Cd (M, D2_1)] and [Cd (M, D2_2)]. Register as protected data.

(3) Protected Data Acquisition Process FIG. 8 is an explanatory diagram of the protected data acquisition process. As shown in the figure, when the user inputs the reference data key [D1] together with the authentication ID [A1] using the data reference request means 12 of the user terminal 1, the user terminal 1 receives the request from the application server 4. The data reference means 43 is requested to refer to data together with the authentication ID [A1] and the reference data key [D1].

  The data reference means 43 gives the authentication ID [A1] to the authentication information reference means 42, whereby the user ID [U1] is linked to the authentication ID [A1] via the authentication information providing means 22 of the authentication server 2. Get the revision [R1], key hash [Hk (P1_1)], and add it to the authentication information in the application server 4 as new.

  Next, the data reference means 43 gives the user ID [U1], the revision [R1], the key hash [Hk (P1_1)] and the reference data key [D1] to the data reading means 53 of the data server 5, Request a reference to protected data.

  The data reading means 53 acquires an encrypted key [Ck (Hk (P1_1), M)] associated with the user ID [U1] and the revision [R1] from the key information held by the user DB 3; The master key [M] is decrypted using the key hash [Hk (P1_1)]. Next, the data reading means 53 decrypts [Cd (M, D1_1)] and [Cd (M, D1_2)] held by the protected data using the master key [M], and respectively references data values [D1_1]. , [D1_2] to the data reference means 43. Finally, the data reference means 43 responds to the data reference request means 12 with the received reference data values [D1_1], [D1_2].

(4) First Password Change Processing FIG. 9 is an explanatory diagram of password change processing in response to a request from the same user. As shown in the figure, the user uses the password change request means 14 of the user terminal 1, and along with the authentication ID [A1], the user ID of the logged-in user himself (hereinafter referred to as his own user ID) [U1], When the new password [P1_2] is input, the user terminal 1 requests the password changing means 23 of the authentication server 2 to change the password together with the authentication ID [A1] and the user IDs [U1] and [P1_2].

  Among the authentication information held by the password changing means 23, the password changing means 23 is linked to the authentication ID [A1], and has its own user ID [U1] and the revision before the change (hereinafter referred to as old password) (hereinafter referred to as old) A key hash [Hk (P1_1)] generated from the old password [P1_1] is obtained from the old password [P1_1], and a key hash [Hk (P1_2)] is generated from [P1_2].

  Next, the password changing unit 23 causes the key re-encrypting unit 33 of the user DB 3 to receive the user ID [U1], the revision [R1], the key hash [Hk (P1_1)], the user ID [U1], the key hash Give [Hk (P1_2)] and request re-encryption of the master key [M].

  The key re-encrypting means 33 extracts the old encrypted key [Ck (Hk (P1_1), M)] associated with the user ID [U1] and the revision [R1] among the key information held by the user DB 3 Acquire and decrypt the master key [M] using the key hash [Hk (P1_1)]. Further, among the revisions associated with the user ID [U1], the latest old revision [R1] is acquired.

  Next, the key re-encryption means 33 encrypts the master key [M] using [Hk (P1_2)], and the generated new encrypted key [Ck (Hk (P1_2), M)], the user Add ID [U1] and new revision [R2] to key information.

  Finally, the password change unit 23 uses the key re-encryption unit 33 to select the revision [R1] associated with the user ID [U1] and the password hash [Hp (P1_1)] in the user information held by the user DB 3. The overwrite is updated with the password hash [Hp (P1_2)] generated from the revision [R2] and the new password [P1_2] received as a response, and the password change request means 14 is responded.

(5) Second Password Change Processing FIG. 10 is an explanatory diagram of password change processing at the request of another user. As shown in the figure, the user uses the password change request means 14 of the user terminal 1 and together with the authentication ID [A1], a user ID other than the login user (hereinafter referred to as another user ID) [U2], When the new password [P2_6] is input, the user terminal 1 requests the password changing means 23 of the authentication server 2 to change the password together with the authentication ID [A1], the other user ID [U2], and the new password [P2_6].

  The password change unit 23 of the authentication server 2 generates the self-user ID [U1], the self-revision [R1], and the self-password [P1_1] from among the authentication information held by itself, which is associated with the authentication ID [A1]. The key hash [Hk (P1_1)] is acquired, and the key hash [Hk (P2_6)] is generated from [P2_6]. Next, the password change unit 23 causes the key re-encryption unit 33 of the user DB 3 to receive the user ID [U1], own revision [R1], key hash [Hk (P1_1)], other user ID [U2], Give [Hk (P2_6)] and request re-encryption of the master key [M].

  Among the key information held by the user DB 3, the key re-encrypting means 33 of the user DB 3 is a self-encrypted key [Ck (Hk (P1_1),), which is associated with the user ID [U1] and the self revision [R1]. M)] and decrypt the master key [M] using the key hash [Hk (P1_1)]. Also, among the revisions linked to [U2], the latest old revision [R5] is acquired. Next, the key re-encryption means 33 encrypts the master key [M] using the key hash [Hk (P2_6)], and the generated new encrypted key [Ck (Hk (P2_6), M)]. , Combination of another user ID [U2] and new revision [R6] are newly added to the key information.

  Finally, the password change unit 23 of the authentication server 2 has the revision [R5] associated with the other user ID [U2], the password hash [Hp (p), which is present in the user information held by the user information storage unit 31 of the user DB3. The P.sub.2 P.sub.5) is updated with the password hash [Hp (P.sub.2-6)] generated from the key re-encrypting means 33 in response to [R.sub.6] and [P.sub.2-- 6], and the P.sub.

  When a higher-level user such as an administrator changes the password of a lower-level general user, it is necessary to encrypt the key with a new password set for others, but this key is acquired using its own password, It encrypts using another person's new password, so that others can obtain a key when they use the new password. The structure is the same as in the case of changing the password of the user ((5) above), and the object of processing is only changed to the user information of another person.

(6) Authentication Maintenance Process FIG. 11 is an explanatory diagram of the authentication maintenance process. As shown in the figure, the authentication maintenance request means 44 of the application server 4 periodically extracts the one currently used from the authentication information held by its own machine, and the corresponding time is used as the current time. Overwrite and update. Also, the authentication maintenance request means 44 periodically requests the authentication maintenance means 24 of the authentication server 2 to perform the authentication maintenance together with the authentication ID ([A1], [A2]) included in the authentication information held by the own device. .

  The authentication maintaining means 24 of the authentication server 2 matches the authentication ID [A1] and [A2] given from the application server 4 (authentication maintaining request means 44) with the authentication information held by the own machine, and ties them to the same authentication ID. The time is updated at the current time [T6], and the authentication maintenance request means 44 is responded.

(7) Key Information Cleaning Process FIG. 12 is an explanatory diagram of the key information cleaning process. As shown in the figure, the key cleaning means 26 of the authentication server 2 periodically associates the old revision with the user ID from the key information held by the user DB 3 and acquires it.

  Next, the key cleaning means 26 sets the acquired user ID and old revision for each of the authentication information confirmation means 25 and the other authentication server 2 '(authentication information confirmation means 25) of the same server ([U1]. , [R3], ([U1], [R4]), ([U2], [R3]) are requested to confirm that they are not included in the authentication information.

  The authentication information confirmation unit 25 matches the pair of the user ID given and the old revision with the authentication information, and confirms the existence ([U1], [R3], true), ([U1], [R4], false) , ([U 2], [R 3], false) are sent to the key cleaning means 26.

  Finally, the key cleaning means 26 deletes the pair ([U1], [R4]) and ([U2], [R3]) of the user ID and the old revision which are found not to exist in the authentication information from the key information Do. By confirming from the user DB 3 that the encrypted key of the past revision is no longer used and deleting it from the user DB 3, it is possible to prevent the old data that is no longer needed from being kept stored in the user DB 3. The same processing is performed in the other authentication server 2 '.

(8) Authentication Information Deletion Process FIG. 13 is an explanatory diagram of the authentication information deletion process. As shown in the figure, the authentication deletion means 27 (or the authentication deletion means 45) of the authentication server 2 (or the application server 4) periodically sets the current time from the authentication information held by the own device. Delete information that is older than a certain period of time, ie, older than a certain period of time since the last authentication.

  Hereinafter, a series of operations of the encryption key management system configured as described above will be described. FIG. 14 is a sequence diagram showing an example of an operation at the time of password change in the encryption key management system according to an embodiment.

First, the user terminal 1 transmits input information {user ID_1, password_1} from the user to the authentication server 2 and makes an authentication request (S101).
Next, the authentication server 2 creates a key hash based on the password_1 (S102), and compares it with the key hash_1 of the latest revision_1 associated with the same user ID in the stored authentication information (S103). If the comparison results match, the authentication server 2 sends an authentication ID {authentication ID_1} back to the user terminal 1 (S104).

Next, the user terminal 1 makes a connection request to the application server 4 based on the authentication ID {authentication ID_1} (S105).
Next, when the application server 4 requests the authentication server 2 to refer authentication information based on the authentication ID {authentication ID_1} (S106), the authentication server 2 authenticates the authentication ID {authentication ID_1}, revision {revision_1}, key Authentication information including the hash {key hash_1} is returned (S107). Then, the application server 4 notifies the user terminal 1 of the connection completion (S108).

  Next, when the user terminal 1 ′ transmits input information {user ID_1, password_1} from the same user to the authentication server 2 and makes an authentication request (S109), the authentication server 2 receives the input password {password_1}. A key hash is created based on (S110), and is compared with the key hash {key hash_1} of the revision {revision_1} associated with the same user ID in the held authentication information (S111). If the comparison results match, the authentication server 2 sends back authentication information {authentication ID_2} different from S104 to the user terminal 1 '(S112).

  Next, when the user terminal 1 ′ transmits a password change request including {authentication ID_2, password_2} to the authentication server 2 (S113), the authentication server 2 performs key hash {key hash_2} by {password_2}. Are stored, and the post-change revision {revision _2} and key hash {key hash _2} are held in a memory area (not shown) (S114).

  Next, the authentication server 2 sends the user DB 3 {revision_1, key hash_1}, {revision_2, key hash_2} associated with {user ID_1}, and requests key re-encryption. (S115). The difference from the prior art is that it not only creates an encrypted key that can be decrypted with the new password key hash {key hash_2} but also an encrypted key that can be decrypted with the old password key hash {key hash_1}. To leave.

  Next, when the key re-encryption is completed, the user DB 3 notifies the authentication server 2 of this (S116). That is, at this point in time, the two user terminals 1 and 1 'have been authenticated with different authentication IDs.

  Next, when the authenticated user terminal 1 requests the application server 4 for data reference (S117), the application server 4 sends {revision_1, key hash_1} to the data server 5 to read data. (S118).

  Next, the user DB 3 requests the data server 5 to transmit the encrypted key which can be decrypted by the key hash {key hash_1} (S119), and the user DB 3 returns this (S120).

Next, the data server 5 decrypts the encrypted key by key hash {key hash_1} to obtain a master key (S121), decrypts protected data with this master key, and reads it (S122), read data Are sent to the application server 4 (S123).
Then, the application server 4 causes the user terminal 1 to start data reference (S124).

As described above, according to the encryption key management system according to the present embodiment, the following effects can be obtained.
(1) Even when the password is changed in parallel while the authenticated user is using the system, without performing re-authentication, the combination of password revision before password change and user ID The protected data can be continuously decrypted by the encrypted key. For example, even when the user terminal 1 is connected to a plurality of application servers 4, there is an advantage that there is no need to re-authenticate for each application server 4.
(2) Even when the password is changed by another user who is using the authentication information of the same authentication ID, the authenticated user can continue the registration / reading work of protection data.
(3) Even when the process started based on the old key hash takes a long time or the number of application servers is large, re-authentication, lock, process for synchronization of encryption related information by password change There is no waiting for completion, etc., and operability improves.

  Although the embodiments of the present invention have been described above, the embodiments are presented as examples and are not intended to limit the scope of the invention. This novel embodiment can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. The present embodiment and the modifications thereof are included in the scope and the gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

1 ... User terminal,
2 ... authentication server,
3 ... User DB,
4 ... application server,
5 ... data server,
11: Authentication request means,
12 ... Data reference request means,
13 ... Data registration request means,
14: Password change request means,
21 ... authentication means,
22: Means for providing authentication information,
23: Password change means,
24 ... Means of maintaining certification,
25 ... authentication information confirmation means,
26 ... Key cleaning means,
27 ... authentication deletion means,
31: User information storage means,
32: Key information storage means,
33: Key re-encryption means,
41: Data registration means,
42 ... authentication information reference means,
43 ... data reference means,
44. Means for requesting maintenance of certification,
45 ... authentication deletion means,
51 ... protected data storage means,
52: Data writing means,
53: Data reading means.

Claims (5)

A server that encrypts and decrypts protected data with a master key;
A user terminal that requests the server for user authentication based on input information including a user ID and a password, and requests encryption and decryption of the protected data;
The server
User information storage means for storing user information associated with the user ID, a password hash calculated from the password, and a revision of the password hash;
Key information storage means for storing key information in which the master ID is encrypted by the key hash calculated from the user ID, the password, and key information in which the revision is associated;
When the user authentication is completed by comparing the input information with the user information, an authentication ID is issued, and the user ID, the revision, the key hash, and the authentication time are issued to the authentication ID. An authentication unit that generates and holds associated authentication information;
When the password is changed to a new password, the encrypted key acquired from the key information is decrypted using the key hash with the combination of the user ID and the revision included in the authentication information as a search key. While acquiring the master key, a new encrypted key is created based on the new password and the master key, the user ID, a new revision related to the new password, and the new encrypted Key re-encryption means for storing new key information associated with a key in the key information storage means in the state of coexistence with other key information related to the same user ID;
The encryption key management system characterized by having.   The key re-encrypting means is configured to use the other password in response to a password change request to associate another user ID different from that at the time of authentication and another password with respect to the common authentication ID from the user terminal side. The key hash is generated, the user ID associated with the common authentication ID from the authentication information, the key hash is acquired, the master key is decrypted, and the other key hash is decoded by the master key. 2. The encryption according to claim 1, wherein the key information storage means stores other key information obtained by combining another encrypted key encrypted, the other user ID, and the revision of the other password. Key management system.   When the combination of the user ID and the revision included in key information stored in the key information storage means does not exist in the authentication information stored in the authentication means, the combination does not exist The encryption key management system according to claim 1 or 2, further comprising key cleaning means for deleting the corresponding key information from the key information storage means.   The server is configured by distributing and arranging the authentication means, the key re-encryption means, the user information storage means and the key information storage means in two or more computers, and connecting them via a network. The encryption key management system according to any one of claims 1 to 3. A server that encrypts and decrypts protected data with a master key, and a user terminal that requests the server for user authentication based on input information including a user ID and a password, and also requests encryption and decryption of the protected data. A method of managing encryption keys in a computer system comprising
A user information storing step of storing, in a storage area, user information in which the server associates the user ID, a password hash calculated from the password, and a revision of the password hash in a storage area;
A key information storage step of storing, in the storage area, key information in which the master ID is encrypted by the key hash calculated from the user ID, the encrypted key, and key information in which the revision is associated;
When the user authentication is completed by comparing the input information with the user information, an authentication ID is issued, and the user ID, the revision, the key hash, and the authentication time are issued to the authentication ID. An authentication step of generating and holding associated authentication information;
When changing the password input in the user authentication to a new password, the encrypted key obtained from the key information using the combination of the user ID and the revision included in the authentication information as a search key is The key hash contained in the authentication information is decrypted to obtain the master key, and a new encrypted key is created based on the new password and the master key, and the user ID, the new password And a key re-encryption step of storing new key information associated with the new encrypted key and new key information associated with the new encrypted key in the storage area in coexistence with other key information associated with the same user ID. ,
A cryptographic key management method comprising:

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