JP2016192715A - Encryption key management system and encryption key management method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow for continuous decryption of protection data with an old decryption key before changing a password, without performing re-authentication, when the password is changed in parallel, while an authenticated user is using a system.SOLUTION: In an encryption key management system, a server acquires a master key by decrypting an encrypted key, acquired from the key information with a combination of the user ID included in the authentication information and the revision as a search key, by a key hash included in the authentication information, when changing the password inputted in the user authentication into a new password, and creates a new encrypted key based on the new password and the master key, and stores the new key information associating the user ID, the new revision related to the new password and the new encrypted key, in the key information storage means, while coexisting with other key information related to the same user ID.SELECTED DRAWING: Figure 1

Description

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

  In recent years, not only can information be protected by user authentication for confidential information such as personal information (hereinafter referred to as confidential information), but also database replication, HDD extraction (secondary storage fraud), or backup media theft ( There is a need for a system that can protect confidential information even if information stored in secondary storage or tertiary storage is stolen, such as fraud of tertiary storage.

  In response to such a request, a system is known 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 this information is fraudulent, it becomes possible to decrypt the encrypted confidential information with the encryption key.

  Therefore, a technique for storing an encryption key (key hash) created from information (for example, a password) that only the user who uses the system knows in the system is effective.

JP 2012-79231 A

  However, in the prior art, when a user changes a password in parallel while using the system after authentication, an encryption key created at the time of authentication (hereinafter referred to as an old encryption key) and a new password are changed. The contents of the created encryption key (hereinafter referred to as the new encryption key) are different. As a result, if information that has been concealed using the old encryption key (protected data) is decrypted with the new encryption key, it will fail. To avoid errors during decryption, new authentication will be performed after re-authentication. There was a problem that the encryption key had to be created and the work efficiency was reduced.

  Therefore, in view of the above-described problems of the prior art, the present invention changes the password without executing re-authentication when the password is changed in parallel when the authenticated user uses the system. The protection data encrypted with the previous old encryption key can be continuously decrypted.

  The encryption key management system according to the present embodiment requests the server for user authentication via the network based on the input information including the server that encrypts and decrypts the protected data with the master key and the user ID and the password, A user terminal that requests encryption and decryption of the protected data, wherein the server includes the user ID, a password hash calculated from the password, and a revision of the password hash. User information storage means for storing associated user information, an encrypted key obtained by encrypting the master key using a key hash calculated from the user ID and the password, and a key for storing key information associated with 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. And when the password is changed to a new password, the encrypted key acquired from the key information using the combination of the user ID and the revision included in the authentication information as a search key, Decrypting with a hash to obtain the master key, creating a new encrypted key based on the new password and the master key, the user ID, a new revision for the new password, and the The new key information associated with the new encrypted key is stored together with other key information related to the same user ID. And having a key re-encryption unit for storing the key information storing means.

The block diagram which shows an example of the whole structure of the encryption key management system which concerns on one 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 of the same user. Explanatory drawing of the password change process by the request | requirement of another user. Explanatory drawing of an authentication maintenance process. Explanatory drawing of a key information cleaning process. Explanatory drawing of an authentication information deletion process. The sequence diagram which shows an example of the operation | movement at the time of the password change in the encryption key management system which concerns on one 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 illustrating an example of the overall configuration of an encryption 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 CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input device, a display device, an HDD (Hard Disk Drive), and a large-capacity storage device, and a communication device. It is a configured computer, and the number of each is arbitrary. Further, although the present system includes a plurality of servers, it may be connected to the network after being appropriately integrated or distributed to one or a plurality of servers.

  The user terminal 1 is an information terminal such as a personal computer used by a user for data editing work, and has 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 unit 11 transmits input information including a user ID and a password to the authentication server 2 and requests a user authentication process. After the user authentication is completed, the data reference request unit 12 connects to the application server 4 based on the authentication information, and requests protection data reference processing managed in the data server 5.

  The data registration request unit 13 connects to the application server 4 based on the authentication information, and requests the data server 5 to register protected data. The password change request unit 14 requests the authentication server 2 to change the existing password to a new password.

  The authentication server 2 is a server computer that executes an authentication process, and includes an authentication information providing unit 22, a password changing unit 23, an authentication maintaining unit 24, an authentication information confirmation unit 25, a key cleaning unit 26, and an authentication deletion unit 27. Yes.

  The authentication unit 21 performs user authentication by comparing the new password hash calculated from the user ID and password included in the input information with the user information stored in the user DB 3. When the user authentication is completed (successful), the authentication unit 21 issues a unique authentication ID, and for this authentication ID, a unique user ID for each user, a revision that is a password generation number, and a key hash , And authentication information associated with the authentication time is generated and held. The key hash is calculated using a predetermined hash function.

  FIG. 2 is a diagram illustrating an example of authentication information. Here, it is shown that the authentication information is information that associates the user ID, revision, key hash, and last access time of the authentication information for each authentication ID. The key hash is calculated using a key hash function Hk (x). The password plaintext Pn_m (n: user number, m: revision number) 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 authentication information of the authentication ID to the application server 4.
When there is a password change request from the user terminal 1, the password changing unit 23 transmits new user information including the user ID, the password hash calculated from the new password, and the password revision to the user DB 3. Update information. Also, the password changing unit 23 transmits the user ID, the current password revision and key hash, and the key hash based on the new password to the user DB 3 to register new key information.

When the authentication maintaining unit 24 receives the authentication ID of the authentication information held by the application server 4, the authentication maintaining unit 24 searches the authentication information held in the authentication server 2 based on the received authentication ID, and the authentication information with the matching authentication ID The authentication is maintained by updating the current time to the current time.
The authentication information confirmation unit 25 confirms whether or not authentication information corresponding to the combination information of the user ID and the revision received from the key cleaning unit 26 exists in the authentication server 2, and the confirmation result for each combination is stored in the key cleaning unit. 26.

The key cleaning unit 26 refers to the key information stored in the user DB 3, extracts the combination information of the user ID and the revision, and periodically transmits it to the authentication information confirmation unit 25. If there is key information that does not exist in the authentication server 2 as 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 timeout time has elapsed.

  The user DB 3 is a database that stores information necessary for authentication processing in the authentication server 2 and data writing / reading processing in the data server 5, and includes user information storage means 31, key information storage means 32, and key re-encryption means 33. have.

  The user information storage unit 31 stores user information that associates a user ID, a password hash, and a revision that specify a user. FIG. 3 is a diagram illustrating an example of user information. The password hash is calculated using a hash function Hp (x) for password. The password plaintext Pn_m (n: user number, m: revision number) is used as x of the hash function Hp (x).

  The key information storage unit 32 stores key information in which the user ID, the revision, and the encrypted key are associated with each other. FIG. 4 is a diagram illustrating an example of key information. The encrypted key is calculated using the key function Ck (x, y). 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, when changing the password entered in the user authentication to a new password, uses the encrypted key acquired from the key information using the combination of the user ID and the revision included in the authentication information as a search key. , Decrypting with the key hash included in the authentication information to obtain the master key, creating a new encrypted key based on the new password and master key, the 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 a state where the new key information coexists with other key information related to the same user ID.

  Also, the key re-encryption means 33 receives a password change request for associating another common user ID and another password with the common authentication ID from the user terminal 1 side. Is generated, and the master key is decrypted by acquiring the user ID and the key hash associated with the common authentication ID from the authentication information held in the authentication server 2, and the master key is used to decrypt another key. Other key information obtained by combining another encrypted key obtained by encrypting the hash, another user ID, and another password revision is stored in the key information storage unit 32.

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

The data registration unit 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 becomes necessary as the application is executed.

When there is a data reference request from the authenticated user terminal 1, the data reference unit 43 acquires the protection data from the data server 5 and returns it to the user terminal 1.
The authentication maintenance request unit 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 deleting 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 protected data storage means 51, data writing means 52, and data reading means 53.

  The protection data storage means 51 encrypts the protection data requested for registration from the user terminal 1 via the application server 4 and stores it for each data ID. FIG. 5 is a diagram illustrating an example of the protection data. Here, the protection data is stored in association with the data ID specifying the protection data by encrypting the data for each column using the data function Cd (x, y). Here, x in the function Cd (x, y) is the master key M, and y is the plaintext (n: data number, m: column) of the 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 this into the protected data storage means 51 as protected data. The data reading unit 53 reads the protected data encrypted from the protected data storage unit 51, decrypts it with the master key decrypted from the encrypted key information key, and transmits 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 Processing FIG. 6 is an explanatory diagram of user authentication processing. As shown in the figure, when the user inputs the user ID [U1] and the password [P1_1] using the authentication request unit 11 of the user terminal 1, the user terminal 1 sends the authentication unit 21 of the authentication server 2 to the authentication unit 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 user ID [U1] and the password hash [Hp (P1_1)] generated from the password [P1_1] with the user information held in the user DB 3. In addition to the user ID [U1] and the password hash [Hp (P1_1)], the user information has a revision [R1] that represents the number of times the password hash has been updated.

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

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

  The data registration unit 41 gives the authentication ID [A1] to the authentication information reference unit 42, thereby the user ID [U1], which is associated with the authentication ID [A1] via the authentication information providing unit 22 of the authentication server 2. The revision [R1] and the key hash [Hk (P1_1)] are acquired, and they are newly added to the authentication information in the application server 4.

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

  The data writing means 52 acquires the 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. Then, the master key [M] is decrypted 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 [Cd (M, D2_1)] and [Cd (M, D2_2)], respectively. As registered in protected data.

(3) Protection Data Acquisition Processing FIG. 8 is an explanatory diagram of protection data acquisition processing. 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 unit 12 of the user terminal 1, the user terminal 1 The data reference unit 43 is requested to refer to the 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, and thereby associates the user ID [U1] with the authentication ID [A1] via the authentication information providing means 22 of the authentication server 2. The revision [R1] and the key hash [Hk (P1_1)] are acquired and newly added to the authentication information in the application server 4.

  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 obtains 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 in the protected data using the master key [M], and respectively references the reference data value [D1_1] , [D1_2] is returned to the data reference means 43. Finally, the data reference unit 43 responds to the data reference request unit 12 with the received reference data values [D1_1] and [D1_2].

(4) First Password Change Process FIG. 9 is an explanatory diagram of a password change process requested by the same user. As shown in the figure, the user uses the password change requesting means 14 of the user terminal 1 together with the authentication ID [A1] and the logged-in user's own user ID (hereinafter referred to as own user ID) [U1], When the new password [P1_2] is input, the user terminal 1 requests the password changing unit 23 of the authentication server 2 to change the password together with the authentication ID [A1], the user ID [U1], and [P1_2].

  The password changing unit 23 is associated with the authentication ID [A1] from the authentication information held by itself, and the revision (hereinafter referred to as the old password) of the user ID [U1] and the password before the change (hereinafter referred to as the old password). This is called a revision.) [R1], the key hash [Hk (P1_1)] generated from the old password [P1_1] is acquired, and further the key hash [Hk (P1_2)] is generated from [P1_2].

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

  The key re-encryption means 33 obtains the old 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. Obtaining and decrypting the master key [M] using the key hash [Hk (P1_1)]. Also, the latest old revision [R1] is acquired from the revisions associated with the user ID [U1].

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

  Finally, the password changing unit 23 sends the revision [R1] associated with the user ID [U1] and the password hash [Hp (P1_1)] existing in the user information held by the user DB 3 from the key re-encryption unit 33. The update 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 response to the password change request means 14 is made.

(5) Second Password Change Processing FIG. 10 is an explanatory diagram of password change processing according to another user's request. As shown in the figure, the user uses the password change requesting means 14 of the user terminal 1 together with the authentication ID [A1] and a user ID other than the login user (hereinafter referred to as other user ID) [U2], When the new password [P2_6] is input, the user terminal 1 requests the password change 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 changing means 23 of the authentication server 2 is generated from the own user ID [U1], the own revision [R1], and the own password [P1_1] associated with the authentication ID [A1] from the authentication information held by itself. The key hash [Hk (P1_1)] is acquired, and the key hash [Hk (P2_6)] is generated from [P2_6]. Next, the password changing unit 23 sends the user ID [U1], its own revision [R1], the key hash [Hk (P1_1)], the other user ID [U2], to the key re-encrypting unit 33 of the user DB3. Given [Hk (P2_6)], request re-encryption of the master key [M].

  The key re-encryption means 33 of the user DB 3 includes the self-encrypted key [Ck (Hk (P1_1),) associated with the user ID [U1] and the self-revision [R1] from the key information held by the user DB 3. M)] is obtained, and the master key [M] is decrypted using the key hash [Hk (P1_1)]. Also, the latest old revision [R5] is acquired from the revisions associated with [U2]. Next, the key re-encryption means 33 encrypts the master key [M] using the key hash [Hk (P2_6)], and generates a new encrypted key [Ck (Hk (P2_6), M)]. The combination of the other user ID [U2] and the new revision [R6] is newly added to the key information.

  Finally, the password changing unit 23 of the authentication server 2 includes the revision [R5] associated with the other user ID [U2] and the password hash [Hp (H) in the user information stored in the user information storage unit 31 of the user DB 3. P2_5)] is updated with the password hash [Hp (P2_6)] generated from [R6] and [P2_6] received as a response from the key re-encryption means 33, and responds to the password change request means 14.

  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 with another person's new password so that the key can be obtained when someone else uses the new password. The mechanism is the same as when changing the password of the person ((5) above), and the processing target is simply 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 requesting means 44 of the application server 4 periodically extracts the currently used information from the authentication information held by itself, and sets the corresponding time as the current time. Update overwriting with. Further, the authentication maintenance request unit 44 periodically requests the authentication maintenance unit 24 of the authentication server 2 to maintain authentication together with the authentication ID ([A1], [A2]) included in the authentication information held by itself. .

  The authentication maintaining means 24 of the authentication server 2 matches the authentication IDs [A1] and [A2] given from the application server 4 (authentication maintenance requesting means 44) with the authentication information held by the own device, and associates them with the same authentication ID. The time is overwritten with the current time [T6], and the response is made to the authentication maintenance request means 44.

(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 acquires an old revision associated with the user ID from the key information held by the user DB 3.

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

  The authentication information confirmation means 25 matches the given user ID and the old revision pair with the authentication information, and the existence confirmation result ([U1], [R3], true), ([U1], [R4], false) , ([U2], [R3], false) are returned 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. To do. By confirming 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 old data that is no longer needed from being stored in the user DB 3. It is assumed that 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 authentication deletion means 45) of the authentication server 2 (or application server 4) periodically checks the current time from the authentication information held by itself. Information that is older than a certain time since the last authentication, that is, information that has passed a certain time since the last authentication is deleted.

  Hereinafter, a series of operations of the encryption key management system configured as described above will be described. FIG. 14 is a sequence diagram illustrating an example of an operation when changing a password in the encryption key management system according to the 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 user ID in the held authentication information (S103). If the comparison results match, the authentication server 2 returns an authentication ID {authentication ID_1} 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 to 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 completion of connection (S108).

  Next, when the user terminal 1 ′ transmits the 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 the key hash (S110) and compared with the key hash {key hash_1} of the revision {revision_1} associated with the user ID in the stored authentication information (S111). If the comparison results match, the authentication server 2 returns 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 uses the key hash {key hash_2} based on {password_2}. And the revised revision {revision_2} and key hash {key hash_2} are stored in a memory area (not shown) (S114).

  Next, the authentication server 2 transmits {revision_1, key hash_1}, {revision_2, key hash_2} associated with {user ID_1} to the user DB 3, and requests key re-encryption. (S115). The difference from the prior art is that not only the encrypted key that can be decrypted with the key hash {key hash_2} of the new password but also the encrypted key that can be decrypted with the key hash {key hash_1} of the old password. Is 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, the two user terminals 1 and 1 'have already been authenticated with different authentication IDs.

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

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

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

As described above, the encryption key management system according to the present embodiment has the following effects.
(1) When an authenticated user uses the system, even if the password is changed in parallel, the combination of the password revision before the password change and the user ID is performed without performing re-authentication. With this encrypted key, the protected data can be continuously decrypted. For example, even when the user terminal 1 is connected to a plurality of application servers 4, there is an advantage that it is not necessary to perform re-authentication 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 to register and read the protection data.
(3) Re-authentication, locking, and processing to synchronize encryption-related information by changing passwords, even when processing started based on old key hashes takes time or when the number of application servers is large There is no waiting for completion and the operability is improved.

  As mentioned above, although embodiment of this invention was described, this embodiment is shown as an example and is not intending limiting the range of invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents 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: Authentication information providing means,
23 ... Password change means,
24. Authentication maintenance means,
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 ... Authentication maintenance request means,
45. Authentication deletion means,
51. Protection data storage means,
52. Data writing means,
53: Data reading means.

Claims (5)

A server that encrypts and decrypts the protected data with a master key;
Requesting the server for user authentication based on input information including a user ID and a password, and a user terminal requesting encryption and decryption of the protection data,
The server is
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 the user ID, an encrypted key obtained by encrypting the master key with a key hash calculated from the password, and key information associated with the revision;
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 set for the authentication ID. An authentication means for generating and storing the associated authentication information;
When the password is changed to a new password, the encrypted key acquired from the key information using the combination of the user ID and the revision included in the authentication information as a search key is decrypted with the key hash. Obtaining the master key and creating a new encrypted key 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 A key re-encryption unit that stores new key information associated with a key in the key information storage unit in a state of coexisting with other key information related to the same user ID;
An encryption key management system comprising:   When the key re-encryption means receives a password change request for associating another common user ID and another password with the common authentication ID from the user terminal side, another password is requested from the other password. And generating the user ID and the key hash associated with the common authentication ID from the authentication information, decrypting the master key, and using the master key, the other key hash is obtained. 2. The encryption according to claim 1, wherein other key information obtained by combining another encrypted key encrypted, the other user ID, and the revision of the other password is stored in the key information storage unit. Key management system.   When the combination of the user ID and the revision included in the key information stored in the key information storage means does not exist in the authentication information held in the authentication means, the combination that does not exist The encryption key management system according to claim 1, further comprising a key cleaning unit that deletes the corresponding key information from the key information storage unit.   The server is configured by distributing the authentication unit, the key re-encryption unit, the user information storage unit, and the key information storage unit in two or more computers and connect them to each other 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 user authentication to the server based on input information including a user ID and a password, and requests encryption and decryption of the protected data An encryption key management method in a computer system comprising:
A user information storage step in which the server stores, in a storage area, user information associated with the user ID, a password hash calculated from the password, and a revision of the password hash;
A key information storage step of storing in the storage area key information associated with the user ID, an encrypted key obtained by encrypting the master key with a key hash calculated from the password, and the revision;
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 set for the authentication ID. An authentication step for generating and maintaining associated authentication information;
When changing the password entered in the user authentication to a new password, the encrypted key acquired from the key information using a combination of the user ID and the revision included in the authentication information as a search key, The master key is obtained by decrypting with the key hash included in the authentication information, and a new encrypted key is created based on the new password and the master key, and the user ID, the new password Re-encrypting the new revision associated with the new encrypted key and storing the new key information associated with the new encrypted key in the storage area in a state where the new key information is associated with the other key information associated with the same user ID; ,
An encryption key management method comprising:

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