JP2009187140A - Access control device, access control method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve flexible access control by giving one attribute key to each user. <P>SOLUTION: The attribute information of a user is processed with a secret key, to generate one attribute key. The generated attribute key is transmitted to the user in advance. A condition index designating a conditional formula for access control is generated, and specific data are encrypted with information acquired by combining a prepared key with the generated conditional index, and information acquired by combining the prepared key with the condition index designating the conditional formula for access control is encrypted with a public key. When accessing the specific data, the attribute key is received from the user, and the matching between the conditional index and the received attribute key is determined, and when the matching between the conditional index with the attribute key is successful, the encrypted information is decrypted, and the decrypted key is output. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an access control apparatus, an access control method, and a program that execute access control for specific data offline.

  In recent years, various information security technologies have been realized along with the development of computer and network technologies or the development of information services using them. One technique for realizing this information security is access control. Access control is a function that regulates permission or disapproval of access to an object for each user. Generally, access to a computer resource requested by a subject identified by user authentication or the like is set in advance. For example, there is a technique for controlling whether to permit or prohibit using the access control list. By using such an access control technology, information security that allows only specific resources to be used in a specific individual / specific terminal relationship is realized, and computer resources can be protected from various malicious unauthorized access. .

The access control includes online access control for executing access control online and offline access control for executing access control offline. Here, as one method for realizing offline access control, there is a method in which an object is encrypted and a key is distributed only to a user permitted to access. For example, Role-Based
When the access control (RBAC) is realized by encryption, it is necessary to assign one key to each role.

Furthermore, a technique described in Non-Patent Document 1 is known as a technique for realizing a searchable encrypted database. In this technique, a user having a token corresponding to the conditional expression PεΦ can search and decrypt the encrypted message M to which the target index I with P (I) = 1 is added. This method is Hidden
It is called Vector Encryption (HVE) and is realized using pairing.

The encryption processing, token issue processing, and decryption processing using HVE are performed as follows. That is, the message creator encrypts the message M with the target index I2Z _lm added with the public key, and obtains the ciphertext C. _Further , processing is performed with the search index Iσ2Z _lσ key, and a token TKI _σ is issued. The user having the token TKI _σ can decrypt the message M to which the target index I of PHVE _3/4 (I) = 1 is added.

The primitives used in HVE are shown below.
(1) Setup (λ)
A function that returns a key pair of a public key PK and a secret key SK for an input security parameter.
(2) Encrypt (PK, I, M)
A function that outputs a ciphertext C for the input target index and data pair (I, M) using the public key PK.
(3) GenToken (SK, [I _* ])
A function that outputs a token TKI _* for the input search index I _* using the secret key SK.
(4) Query (TK, C)
For the input ciphertext C and token TKI _* , if I _* matches I (PHVE _3/4 (I) = 1), data M is decrypted, and if P (I) = 0, decryption fails Output ⊥ which means
D. Boneh and b. Waters, “Conjunctive, Subset, and Range Queries on Encrypted Data,“ Proc. Of TCC 2007, LNCS 4392, pp. 535-554.

However, in the method of encrypting the above-described object and distributing the key only to users who are permitted to access, a user who has been given multiple roles needs to hold multiple keys. There is a problem that management of the system becomes complicated. The technology described in Non-Patent Document 1 requires that a specific key be decrypted by a specific subject based on a conditional expression in offline access control, and a HVE that designates a specific value as a target index.
There is a problem that cannot be used as it is.

  Accordingly, the present invention has been made in view of the above-described problems, and an access control apparatus, an access control method, and an access control apparatus that allow flexible access control with one token (attribute key) held by each user. The purpose is to provide a program.

  The present invention proposes the following matters in order to solve the above problems.

  (1) The present invention is an access control device that executes access control for specific data offline, and processes attribute information of a user with a secret key to generate one attribute key; Transmitting means for transmitting the generated attribute key to the user in advance, Condition index generating means for generating a condition index specifying a conditional expression in access control, a key prepared in advance for the specific data, and the generated condition index Data encryption means for encrypting with the combined information, information encryption means for encrypting information combined with a key prepared in advance and a condition index specifying a conditional expression for access control with a public key, and specifying Receiving means for receiving the attribute key from a user when accessing the data, the condition index and the received attribute key A determination unit for performing a matching determination; and when the matching between the condition index and the attribute key is recognized by the determination unit, the information encrypted by the information encryption unit is decrypted and a decryption key is output. And a decryption key output means for providing an access control device.

  According to the present invention, the attribute key generating means generates one attribute key by processing the user attribute information with the secret key. The transmission unit transmits the generated attribute key to the user in advance. The condition index generating means generates a condition index specifying a conditional expression in access control. The data encryption means encrypts specific data with information obtained by combining a key prepared in advance and the generated condition index. The information encryption means encrypts information obtained by combining a key prepared in advance and a condition index specifying a conditional expression in access control with a public key. The receiving means receives an attribute key from the user when accessing specific data. The determination unit performs matching determination between the condition index and the received attribute key. The decryption key output means decrypts the information encrypted by the information encryption means and outputs the decryption key when the determination means recognizes the matching between the condition index and the attribute key. Therefore, even when there are a plurality of user attributes, one attribute key held by each user can be used and access control for specific data can be executed offline.

  (2) In the access control device according to (1), each attribute includes a bit string expressing an integer value of 1 or more and m or less in m bits, and corresponds to the attribute of the user among the m bits. The bit is 1 and the non-corresponding bit is represented by a symbol representing an arbitrary character string, and the attribute information of the user is information obtained by combining the bit strings of the attributes, and is accessed for a user having a plurality of attributes. When performing access control with a single attribute that matches a condition, the condition index generation means combines the bit strings of the plurality of attributes, and sets a bit string that matches the access condition and a bit string of an attribute that is not used for access control. An access control apparatus is proposed which is characterized by generating a conditional index represented by 1 and other bits represented by 0.

  According to the present invention, each attribute is composed of a bit string that expresses an integer value of 1 or more and m or less in m bits. Among m bits, a bit corresponding to a user attribute is 1, and a non-corresponding bit is an arbitrary character string. When the user attribute information is information that combines the bit strings of each attribute and access control is performed for a user having multiple attributes with a single attribute that matches the access conditions. In addition, the condition index generation means combines a plurality of bit strings of attributes, represents a bit that matches the access condition and a bit string of an attribute that is not used for access control by 1 and other bits are represented by 0, and the condition index is Generate. Therefore, for a user having a plurality of attributes such as affiliation and job title, when one attribute matches the access condition, access control that provides a decryption key can be executed offline regardless of other attributes.

  (3) In the access control device according to (1), each attribute includes a bit string that represents an integer value of 1 to m in m bits, and corresponds to the user attribute among the m bits. The bit is 1 and the non-corresponding bit is represented by a symbol representing an arbitrary character string, and the attribute information of the user is information obtained by combining the bit strings of the attributes, and is accessed for a user having a plurality of attributes. When performing access control with a plurality of attributes connected by an AND operator that matches a condition, the condition index generation means combines the bit strings of the plurality of attributes, and represents a bit that matches the access condition as 1. The access control device is characterized in that the other bits are represented by 0 and a conditional index is generated.

  According to the present invention, each attribute is composed of a bit string that expresses an integer value of 1 or more and m or less in m bits. Among m bits, a bit corresponding to a user attribute is 1, and a non-corresponding bit is an arbitrary character string. The attribute information of the user is information obtained by combining the bit strings of the respective attributes, and a plurality of attributes combined with an AND operator that matches the access condition for a user having a plurality of attributes. When performing the access control according to the above, the conditional index generating means combines the bit strings having a plurality of attributes, represents the bit matching the access condition as 1 and represents the other bits as 0 to generate the conditional index. Therefore, for users with multiple attributes such as affiliation and job title, when access control is performed using multiple attributes combined with an AND operator that matches the access conditions, a decryption key is given only to the users that match the access conditions Access control can be performed offline.

  (4) In the access control device according to (1), each attribute includes a bit string that expresses an integer value of 1 or more and m or less in m bits, and corresponds to the attribute of the user among the m bits. The bit is 1 and the non-corresponding bit is represented by a symbol representing an arbitrary character string, and the attribute information of the user is information obtained by combining the bit strings of the attributes, and is accessed for a user having a plurality of attributes. When performing access control with a plurality of attributes combined with an OR operator that matches a condition, the condition index generation means combines the bit strings of the plurality of attributes, and each attribute combined with the OR operator. On the other hand, a plurality of condition indexes are generated, in which a bit that matches an access condition for one attribute is represented by 1 and other bits are represented by 0. It has proposed a scan controller.

  According to the present invention, each attribute is composed of a bit string that expresses an integer value of 1 or more and m or less in m bits. Among m bits, a bit corresponding to a user attribute is 1, and a bit not corresponding is an arbitrary character string The attribute information of the user is information obtained by combining the bit strings of each attribute, and a plurality of attributes combined with an OR operator that matches the access condition for a user having a plurality of attributes. When the access control is performed by the condition index, the condition index generation unit combines the bit strings of the plurality of attributes, and for each attribute combined by the OR operator, the bit that matches the access condition for one attribute is set to 1. A plurality of conditional indexes are generated, and other bits are represented by 0. Therefore, for users who have multiple attributes such as affiliation and job title, when performing access control with multiple attributes combined with an OR operator that matches the access conditions, a decryption key is given only to the users that match the access conditions Access control can be performed offline.

  (5) The present invention is an access control method for executing access control for specific data offline, comprising a bit string expressing an integer value of 1 or more and m or less in m bits, out of the m bits. The attribute information of the user in which the bit corresponding to the attribute is 1 and the bit string corresponding to the attribute is represented by a symbol representing an arbitrary character string is combined with the secret key to generate one attribute key. A first step, a second step of transmitting the generated attribute key to the user in advance, and access control for a user having a plurality of attributes with a single attribute that matches the access conditions The bit strings of the plurality of attributes are combined, the bit that matches the access condition and the bit string of the attribute that is not used for access control are represented by 1, and the other bits are represented by 0 A third step of generating a conditional index, a fourth step of encrypting the specific data with information prepared by combining the key prepared in advance with the generated conditional index, and preparing the specific data in advance A fifth step of encrypting information obtained by combining the key and a conditional index specifying a conditional expression in access control with a public key, and a sixth step of receiving the attribute key from a user when accessing specific data And a seventh step of performing a matching determination between the conditional index and the received attribute key, and when the matching between the conditional index and the attribute key is recognized by the seventh step, the fifth step And performing an eighth step of decrypting the information encrypted in the step and outputting the decryption key. It has proposed a control method.

  According to the present invention, it consists of a bit string that represents an integer value of 1 or more and m or less in m bits. Of the m bits, the bit corresponding to the user attribute is 1 and the non-corresponding bit is a symbol representing an arbitrary character string. The attribute information of the user that combines the bit strings of each attribute represented is processed with the secret key to generate one attribute key, and the generated attribute key is transmitted to the user in advance. Next, when access control is performed for a user having a plurality of attributes using a single attribute that matches the access condition, the bit string and the access control that match the access condition are combined by combining bit strings of the plurality of attributes. A bit string of an attribute not used in the above is represented by 1 and other bits are represented by 0 to generate a conditional index, and specific data is encrypted with information obtained by combining a key prepared in advance and the generated conditional index. Also, information obtained by combining a key prepared in advance with specific data and a condition index specifying a conditional expression for access control is encrypted with a public key. When accessing specific data, the attribute key is received from the user, the matching between the condition index and the received attribute key is performed, and the encryption is performed when the matching between the condition index and the attribute key is recognized. The decrypted information is decrypted and a decryption key is output. Therefore, for a user having a plurality of attributes such as affiliation and job title, when one attribute matches the access condition, access control that provides a decryption key can be executed offline regardless of other attributes.

  (6) The present invention is an access control method for executing access control for specific data offline, comprising a bit string expressing an integer value of 1 or more and m or less in m bits, out of the m bits. The attribute information of the user in which the bit corresponding to the attribute is 1 and the bit string corresponding to the attribute is represented by a symbol representing an arbitrary character string is combined with the secret key to generate one attribute key. A first step, a second step of transmitting the generated attribute key to the user in advance, and a plurality of attributes combined with an AND operator that matches an access condition for a user having a plurality of attributes. When performing access control, the bit strings of the plurality of attributes are combined, the bit that matches the access condition is represented by 1 and the other bits are represented by 0, and the condition index. A third step of generating a password, a fourth step of encrypting the specific data with information prepared by combining the key prepared in advance with the generated condition index, and a key prepared in advance with the specific data A fifth step of encrypting information combined with a condition index specifying a conditional expression in access control with a public key; a sixth step of receiving the attribute key from a user when accessing specific data; and A seventh step of performing a matching determination between the condition index and the received attribute key; and when the matching between the condition index and the attribute key is recognized by the seventh step, the encryption is performed by the fifth step. An access control method characterized by executing an eighth step of decrypting the encrypted information and outputting a decryption key That.

  According to the present invention, it consists of a bit string that represents an integer value of 1 or more and m or less in m bits. Of the m bits, the bit corresponding to the user attribute is 1 and the non-corresponding bit is a symbol representing an arbitrary character string. The attribute information of the user that combines the bit strings of each attribute represented is processed with the secret key to generate one attribute key, and the generated attribute key is transmitted to the user in advance. Next, when access control is performed for a user having a plurality of attributes using a plurality of attributes combined with an AND operator that matches the access conditions, the bit strings of the plurality of attributes are combined to meet the access conditions. A bit is represented by 1 and the other bits are represented by 0 to generate a conditional index. The specific data is encrypted with information obtained by combining a key prepared in advance and the generated conditional index. Information obtained by combining a key prepared in advance with a condition index specifying a conditional expression for access control is encrypted with a public key. When accessing specific data, the attribute key is received from the user, the matching between the condition index and the received attribute key is performed, and the encryption is performed when the matching between the condition index and the attribute key is recognized. The decrypted information is decrypted and a decryption key is output. Therefore, for users with multiple attributes such as affiliation and job title, when access control is performed using multiple attributes combined with an AND operator that matches the access conditions, a decryption key is given only to the users that match the access conditions Access control can be performed offline.

  (7) The present invention is an access control method for executing access control for specific data offline, comprising a bit string expressing an integer value of 1 or more and m or less in m bits, out of the m bits. The attribute information of the user in which the bit corresponding to the attribute is 1 and the bit string corresponding to the attribute is represented by a symbol representing an arbitrary character string is combined with the secret key to generate one attribute key. A first step, a second step of transmitting the generated attribute key to the user in advance, and a plurality of attributes combined with an OR operator that matches an access condition for a user having a plurality of attributes. When performing access control, the bit strings of the plurality of attributes are combined, and for each attribute connected by the OR operator, a bit that matches the access condition for one attribute. A third step of generating a plurality of conditional indexes in which 1 is represented and other bits are represented by 0, and encrypting the specific data with information obtained by combining a key prepared in advance and the generated conditional index A fourth step, a fifth step of encrypting, with a public key, information obtained by combining a key prepared in advance with the specific data and a conditional index designating a conditional expression in access control; A sixth step of receiving the attribute key from the user, a seventh step of performing a matching determination between the conditional index and the received attribute key, and the conditional index and the attribute key by the seventh step. When the matching is confirmed, the information encrypted in the fifth step is decrypted and the decryption key is output. Have proposed an access control method characterized by performing Tsu and up, the.

  According to the present invention, it consists of a bit string that represents an integer value of 1 or more and m or less in m bits. Of the m bits, the bit corresponding to the user attribute is 1 and the non-corresponding bit is a symbol representing an arbitrary character string. The attribute information of the user that combines the bit strings of each attribute represented is processed with the secret key to generate one attribute key, and the generated attribute key is transmitted to the user in advance. Next, when performing access control with a plurality of attributes combined with an OR operator that matches an access condition for a user having a plurality of attributes, the bit strings of the plurality of attributes are combined, and the OR operator For each attribute that is combined, a key that matches the access condition for one attribute is represented by 1 and a plurality of condition indexes that represent the other bits by 0 are generated, and a key in which specific data is prepared in advance In addition to encrypting the generated conditional index with the combined information, the information combining the key prepared in advance with specific data and the conditional index specifying the conditional expression for access control is encrypted with the public key. When accessing specific data, the attribute key is received from the user, the matching between the condition index and the received attribute key is performed, and the encryption is performed when the matching between the condition index and the attribute key is recognized. The decrypted information is decrypted and a decryption key is output. Therefore, for users who have multiple attributes such as affiliation and job title, when performing access control with multiple attributes combined with an OR operator that matches the access conditions, a decryption key is given only to the users that match the access conditions Access control can be performed offline.

  (8) The present invention is a program for executing access control for specific data offline using a computer, comprising a bit string representing an integer value of 1 to m in m bits, the m bits Among them, the user attribute information obtained by combining the bit string of each attribute represented by a symbol in which the bit corresponding to the attribute of the user is 1 and the non-corresponding bit represents an arbitrary character string is processed by the secret key. A first step of generating an attribute key, a second step of transmitting the generated attribute key to the user in advance, and accessing a user having a plurality of attributes with a single attribute that matches an access condition When performing control, the bit strings of the plurality of attributes are combined, and the bit that matches the access condition and the bit string of the attribute that is not used for access control are represented by 1; A third step in which the other bits are represented by 0 and a conditional index is generated, and a fourth step in which the specific data is encrypted with information obtained by combining the key prepared in advance and the generated conditional index; A fifth step of encrypting, with a public key, information obtained by combining a key prepared in advance with a specific index and a conditional index designating a conditional expression in access control; , A seventh step of performing a matching determination between the condition index and the received attribute key, and a matching between the condition index and the attribute key is recognized by the seventh step. And decrypting the information encrypted in the fifth step and outputting a decryption key. It has proposed a program characterized.

  According to the present invention, it consists of a bit string that represents an integer value of 1 or more and m or less in m bits. Of the m bits, the bit corresponding to the user attribute is 1 and the non-corresponding bit is a symbol representing an arbitrary character string. The attribute information of the user that combines the bit strings of each attribute represented is processed with the secret key to generate one attribute key, and the generated attribute key is transmitted to the user in advance. Next, when access control is performed for a user having a plurality of attributes using a single attribute that matches the access condition, the bit string and the access control that match the access condition are combined by combining bit strings of the plurality of attributes. A bit string of an attribute not used in the above is represented by 1 and other bits are represented by 0 to generate a conditional index, and specific data is encrypted with information obtained by combining a key prepared in advance and the generated conditional index. Also, information obtained by combining a key prepared in advance with specific data and a condition index specifying a conditional expression for access control is encrypted with a public key. When accessing specific data, the attribute key is received from the user, the matching between the condition index and the received attribute key is performed, and the encryption is performed when the matching between the condition index and the attribute key is recognized. The decrypted information is decrypted and a decryption key is output. Therefore, for a user having a plurality of attributes such as affiliation and job title, when one attribute matches the access condition, access control that provides a decryption key can be executed offline regardless of other attributes.

  (9) The present invention is a program for executing access control for specific data offline using a computer, comprising a bit string representing an integer value of 1 to m in m bits, and the m bits Among them, the user attribute information obtained by combining the bit string of each attribute represented by a symbol in which the bit corresponding to the attribute of the user is 1 and the non-corresponding bit represents an arbitrary character string is processed by the secret key. A first step of generating an attribute key, a second step of transmitting the generated attribute key to the user in advance, and a user having a plurality of attributes are combined with an AND operator that matches an access condition. When the access control is performed with a plurality of attributes, the bit strings of the plurality of attributes are combined, the bit meeting the access condition is represented by 1, and the other bits are represented by 0. A third step of generating a conditional index; a fourth step of encrypting the specific data with information prepared by combining a key prepared in advance with the generated conditional index; and A fifth step of encrypting information prepared by combining a prepared key and a condition index specifying a conditional expression in access control with a public key; and a sixth step of receiving the attribute key from a user when accessing specific data And a seventh step of performing matching determination between the condition index and the received attribute key, and when the matching between the condition index and the attribute key is recognized by the seventh step, the fifth step And an eighth step of decrypting the encrypted information and outputting a decryption key. It has proposed the ram.

  According to the present invention, it consists of a bit string that represents an integer value of 1 or more and m or less in m bits. Of the m bits, the bit corresponding to the user attribute is 1 and the non-corresponding bit is a symbol representing an arbitrary character string. The attribute information of the user that combines the bit strings of each attribute represented is processed with the secret key to generate one attribute key, and the generated attribute key is transmitted to the user in advance. Next, when access control is performed for a user having a plurality of attributes using a plurality of attributes combined with an AND operator that matches the access conditions, the bit strings of the plurality of attributes are combined to meet the access conditions. A bit is represented by 1 and the other bits are represented by 0 to generate a conditional index. The specific data is encrypted with information obtained by combining a key prepared in advance and the generated conditional index. Information obtained by combining a key prepared in advance with a condition index specifying a conditional expression for access control is encrypted with a public key. When accessing specific data, the attribute key is received from the user, the matching between the condition index and the received attribute key is performed, and the encryption is performed when the matching between the condition index and the attribute key is recognized. The decrypted information is decrypted and a decryption key is output. Therefore, for users with multiple attributes such as affiliation and job title, when access control is performed using multiple attributes combined with an AND operator that matches the access conditions, a decryption key is given only to the users that match the access conditions Access control can be performed offline.

  (10) The present invention is a program for executing off-line access control for specific data using a computer, comprising a bit string expressing an integer value of 1 to m in m bits, the m bits Among them, the user attribute information obtained by combining the bit string of each attribute represented by a symbol in which the bit corresponding to the attribute of the user is 1 and the non-corresponding bit represents an arbitrary character string is processed by the secret key. A first step of generating an attribute key, a second step of transmitting the generated attribute key to the user in advance, and a user having a plurality of attributes are combined with an OR operator that matches an access condition. When performing access control using a plurality of attributes, the bit strings of the plurality of attributes are combined, and one attribute is assigned to each attribute connected by the OR operator. A third step of generating a plurality of conditional indexes in which a bit matching the access condition is represented by 1 and other bits are represented by 0 is combined with a key prepared in advance for the specific data and the generated conditional index A fourth step of encrypting with a public key, and a fourth step of encrypting information obtained by combining a key prepared in advance with the specific data and a condition index specifying a conditional expression in access control with a public key; When accessing specific data, the sixth step of receiving the attribute key from the user, the seventh step of determining the matching between the condition index and the received attribute key, and the seventh step, When matching between the condition index and the attribute key is recognized, the information encrypted in the fifth step is decrypted and restored. Proposes a program characterized by executing an eighth step of outputting the encryption key, the.

  According to the present invention, it consists of a bit string that represents an integer value of 1 or more and m or less in m bits. Of the m bits, the bit corresponding to the user attribute is 1 and the non-corresponding bit is a symbol representing an arbitrary character string. The attribute information of the user that combines the bit strings of each attribute represented is processed with the secret key to generate one attribute key, and the generated attribute key is transmitted to the user in advance. Next, when performing access control with a plurality of attributes combined with an OR operator that matches an access condition for a user having a plurality of attributes, the bit strings of the plurality of attributes are combined, and the OR operator For each attribute that is combined, a key that matches the access condition for one attribute is represented by 1 and a plurality of condition indexes that represent the other bits by 0 are generated, and a key in which specific data is prepared in advance In addition to encrypting the generated conditional index with the combined information, the information combining the key prepared in advance with specific data and the conditional index specifying the conditional expression for access control is encrypted with the public key. When accessing specific data, the attribute key is received from the user, the matching between the condition index and the received attribute key is performed, and the encryption is performed when the matching between the condition index and the attribute key is recognized. The decrypted information is decrypted and a decryption key is output. Therefore, for users who have multiple attributes such as affiliation and job title, when performing access control with multiple attributes combined with an OR operator that matches the access conditions, a decryption key is given only to the users that match the access conditions Access control can be performed offline.

  According to the present invention, there is an effect that flexible access control can be executed with one attribute key held by each user. Further, if the technology of the present invention is applied to a content distribution service, for example, a service such as distributing privilege content only to premium members or distributing a message from an artist only to users born in December is safe. There is an effect that it can be performed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Note that the constituent elements in the present embodiment can be appropriately replaced with existing constituent elements and the like, and various variations including combinations with other existing constituent elements are possible. Therefore, the description of the present embodiment does not limit the contents of the invention described in the claims.

  The access control apparatus according to the present embodiment will be described with reference to FIGS.

<Configuration of access control device>
As shown in FIG. 1, the access control device according to the present embodiment includes an attribute key generation unit 10, a transmission unit 20, a condition index generation unit 30, a data encryption unit 40, an information encryption unit 50, The receiving unit 60 includes a determination unit 70 and a decryption key output unit 80.

  The attribute key generation unit 10 processes user attribute information with a secret key to generate one attribute key. The transmission unit 20 transmits the attribute key generated by the attribute key generation unit 10 to the user in advance. The condition index generation unit 30 generates a condition index specifying a conditional expression in access control.

  The data encryption unit 40 encrypts specific data with information obtained by combining a key prepared in advance and the generated condition index. The information encryption unit 50 encrypts information obtained by combining a key prepared in advance and a condition index specifying a conditional expression in access control with a public key. The receiving unit 60 receives an attribute key from the user when accessing specific data. The determination unit 70 performs matching determination between the condition index and the received attribute key. The decryption key output unit 80 decrypts the information encrypted by the information encryption unit 50 and outputs the decryption key when the determination unit 70 recognizes that the condition index matches the attribute key. .

<Processing of access control device>
The processing of the access control apparatus will be described using FIG.
First, user attribute information is processed with a secret key to generate one attribute key (step S101), and the generated attribute key is transmitted to the user in advance (step S102). Next, a condition index specifying a conditional expression in access control is generated (step S103), and specific data is encrypted with information obtained by combining a key prepared in advance and the generated condition index (step S104). Then, information obtained by combining a key prepared in advance and a condition index specifying a conditional expression for access control is encrypted with a public key (step S105).

  Then, when accessing specific data, an attribute key is received from the user (step S106), matching between the condition index and the received attribute key is determined (step S107), and matching between the condition index and the attribute key is recognized. When decrypted, the information encrypted in step S104 is decrypted and a decryption key is output (step S108).

<Configuration of attribute key>
Next, the configuration of the attribute key will be described with reference to FIGS.
Here, for simplicity of explanation, the attributes are, for example, two types, affiliation and position, attribute 1 (for example, affiliation) takes an integer value of 1 to m, and attribute 2 (for example, position) is The description will be made assuming that the integer value is 1 or more and n or less. In this case, the condition index and the attribute are a bit string of length m + n, the first m bits correspond to attribute 1, and the remaining n bits correspond to attribute 2. For each attribute, a data table as shown in FIG. 3 is provided.

  If the attribute 1 (for example, affiliation) is x (for example, the technical department in FIG. 3) and the attribute 2 (for example, job title) is y (for example, the department manager in FIG. 3), this attribute A Is processed with a secret key, and an attribute key as shown in FIG. 4 is given. Here, * in FIG. 4 is a symbol representing an arbitrary character string. When an attribute key is used, a primitive in HVE is used as GetToken (SK, [A]).

  Therefore, according to the present embodiment, even when there are a plurality of user attributes, one attribute key held by each user can be set to one, and access control for specific data can be executed offline.

  Hereinafter, specific examples will be described with reference to the drawings.

<Example 1>
Example 1 will be described with reference to FIGS. 5 and 6.
This embodiment corresponds to a case where the user whose attribute 1 value is included in the set X that defines the access condition is allowed to obtain the decryption key K regardless of the attribute 2 value. In this case, the attribute key is encrypted with the public key PK with a condition index C in which the value corresponding to the value included in the set X and the bit corresponding to the attribute 2 are 1 and the other bits are 0. At the time of encryption, E _HVE (PK, C, K) is used using _HVE primitives. However, all bits corresponding to attributes not used for control in the conditional index are set to 1. As an example, FIG. 6 shows the condition index C when X = f1; 3; :::; mg.

Next, the processing of this embodiment will be described with reference to FIG.
First, it consists of a bit string that expresses an integer value of 1 or more and m or less in m bits. Among m bits, a bit corresponding to a user attribute is represented by 1 and a non-corresponding bit is represented by a symbol representing an arbitrary character string. The user attribute information combined with the bit string of each attribute is processed with the secret key to generate one attribute key (step S201), and the generated attribute key is transmitted to the user in advance (step S202).

  Next, when access control is performed for a user having a plurality of attributes using a single attribute that matches the access condition, the bit string and the access control that match the access condition are combined by combining bit strings of the plurality of attributes. A bit string of an attribute not used in the above is represented by 1 and other bits are represented by 0, a condition index is generated (step S203), and information obtained by combining a key prepared in advance with specific data and the generated condition index Encryption is performed (step S204).

  Also, information obtained by combining a key prepared in advance with specific data and a condition index specifying a conditional expression for access control is encrypted with a public key (step S205). Then, when accessing specific data, the attribute key is received from the user (step S206), the condition index and the received attribute key are matched (step S207), and the condition index and the attribute key are matched. When it is recognized, the encrypted information is decrypted and a decryption key is output (step S208).

  Therefore, according to the present embodiment, for a user having a plurality of attributes such as affiliation and job title, when one attribute matches the access condition, access control for giving a decryption key is executed offline regardless of other attributes. it can.

<Example 2>
Example 2 will be described with reference to FIGS. 7 and 8. FIG.
This embodiment corresponds to a case where the key K is obtained only by the user whose attribute 1 value is included in the set X and whose attribute 2 value is included in the set Y. In this case, the key is set X
A condition index C in which the bit corresponding to the value included in Y and Y is 1 and the other bits are 0 is added and encrypted using the public key PK. At the time of encryption, E _HVE (PK, C, K) is used using _HVE primitives. As an example, FIG. 8 shows a conditional index C when X = f1; 3; :::; mg, Y = f2; :::; nilg.

Next, processing of this embodiment will be described with reference to FIG.
First, it consists of a bit string that expresses an integer value of 1 or more and m or less in m bits. Among m bits, a bit corresponding to a user attribute is represented by 1 and a non-corresponding bit is represented by a symbol representing an arbitrary character string. The user attribute information combined with the bit string of each attribute is processed with the secret key to generate one attribute key (step S301), and the generated attribute key is transmitted to the user in advance (step S302).

  Next, when access control is performed for a user having a plurality of attributes using a plurality of attributes combined with an AND operator that matches the access conditions, the bit strings of the plurality of attributes are combined to meet the access conditions. A bit is represented by 1 and the other bits are represented by 0 to generate a conditional index (step S303), and specific data is encrypted with information obtained by combining a previously prepared key and the generated conditional index (step S303). S304).

  Also, information obtained by combining a key prepared in advance with specific data and a condition index specifying a conditional expression for access control is encrypted with a public key (step S305). When accessing specific data, the attribute key is received from the user (step S306), the condition index and the received attribute key are matched (step S307), and the condition index and the attribute key are matched. When it is recognized, the encrypted information is decrypted and a decryption key is output (step S308).

  Therefore, according to the present embodiment, when access control is performed for a user having a plurality of attributes such as affiliation and position with a plurality of attributes combined with an AND operator that matches the access condition, the user that matches the access condition In addition, access control for providing a decryption key can be executed offline.

<Example 3>
Example 3 will be described with reference to FIG.
This embodiment corresponds to a case where a user who satisfies any one of the plurality of conditions defined in the first and second embodiments obtains a key. In this case, it is necessary to individually create a condition index corresponding to each conditional expression. For example, conditional expression P
For OR Q, it is necessary to separately prepare a key to which a condition index _IP corresponding to _P is added and a key to which a condition index I _q corresponding to Q is added. That is, as many ciphertexts as the number of conditions connected by the OR expression are generated. In this embodiment, the size of the ciphertext is proportional to the product of the length of the index and the condition number concatenated with the OR text. Furthermore, the amount of calculation for the user to decrypt the key is proportional to the number of attributes.

Next, the processing of this embodiment will be described with reference to FIG.
First, it consists of a bit string that expresses an integer value of 1 or more and m or less in m bits. Among m bits, a bit corresponding to a user attribute is represented by 1 and a non-corresponding bit is represented by a symbol representing an arbitrary character string. The user attribute information obtained by combining the bit strings of the attributes is processed with the secret key to generate one attribute key (step S401), and the generated attribute key is transmitted to the user in advance (step S402).

  Next, when performing access control with a plurality of attributes combined with an OR operator that matches an access condition for a user having a plurality of attributes, the bit strings of the plurality of attributes are combined, and the OR operator For each of the combined attributes, a plurality of condition indexes are generated in which a bit matching the access condition for one attribute is represented by 1 and the other bits are represented by 0 (step S403). Encryption is performed with information obtained by combining the prepared key and the generated condition index (step S404).

  Also, information obtained by combining a key prepared in advance with specific data and a condition index specifying a conditional expression for access control is encrypted with a public key (step S405). Then, when accessing specific data, the attribute key is received from the user (step S406), the matching between the condition index and the received attribute key is determined (step S407), and the matching between the condition index and the attribute key is performed. When it is recognized, the encrypted information is decrypted and a decryption key is output (step S408).

  Therefore, according to the present embodiment, when access control is performed for a user having a plurality of attributes such as affiliation and job title by a plurality of attributes combined with an OR operator that matches the access condition, the user that matches the access condition In addition, access control for providing a decryption key can be executed offline.

  Note that the access control device and the access control method of the present invention are realized by recording the process of the access control device on a computer-readable recording medium, causing the access control device to read and execute the program recorded on the recording medium. can do. The computer system here includes an OS and hardware such as peripheral devices.

  Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW (World Wide Web) system is used. The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line.

  The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

  The embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to the embodiments, and includes designs and the like that do not depart from the gist of the present invention.

It is a figure which shows the structure of the access control apparatus which concerns on this invention. It is a processing flow of the access control apparatus which concerns on this invention. It is the figure which illustrated the attribute table. It is a figure which shows the structure of an attribute key. 3 is a processing flow according to the first embodiment. It is the figure which illustrated the condition index concerning Example 1. 10 is a processing flow according to the second embodiment. It is the figure which illustrated the condition index concerning Example 2. 10 is a processing flow according to the second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Attribute key generation part 20 ... Transmission part 30 ... Condition index generation part 40 ... Data encryption part 50 ... Information encryption part 60 ... Reception part 70 ... Determination part 80: Decryption key output unit

Claims (10)

An access control device that executes access control for specific data offline,
Attribute key generation means for processing user attribute information with a secret key to generate one attribute key;
Transmitting means for transmitting the generated attribute key to the user in advance;
Condition index generating means for generating a condition index specifying a conditional expression in access control;
Data encryption means for encrypting the specific data with information obtained by combining a key prepared in advance and the generated condition index;
Information encryption means for encrypting information that combines a key prepared in advance and a condition index specifying a conditional expression in access control with a public key;
A receiving means for receiving the attribute key from a user when accessing specific data;
Determination means for performing a matching determination between the condition index and the received attribute key;
A decryption key output means for decrypting the information encrypted by the information encryption means and outputting a decryption key when matching between the condition index and the attribute key is recognized by the determination means;
An access control device comprising: Each attribute consists of a bit string that expresses an integer value of 1 or more and m or less in m bits, and among these m bits, the bit corresponding to the user attribute is 1, and the non-corresponding bit is a symbol representing an arbitrary character string Represented,
The user attribute information is information obtained by combining the bit strings of the attributes,
When access control is performed for a user having a plurality of attributes using a single attribute that matches the access condition, the condition index generation unit combines the bit strings of the plurality of attributes to match the access condition. 2. The access control apparatus according to claim 1, wherein a condition index is generated by expressing a bit string of bits and attributes not used for access control by 1 and other bits by 0. Each attribute consists of a bit string that expresses an integer value of 1 or more and m or less in m bits, and among these m bits, the bit corresponding to the user attribute is 1, and the non-corresponding bit is a symbol representing an arbitrary character string Represented,
The user attribute information is information obtained by combining the bit strings of the attributes,
When a user having a plurality of attributes performs access control with a plurality of attributes combined with an AND operator that matches an access condition, the condition index generation unit combines the bit strings of the plurality of attributes, The access control apparatus according to claim 1, wherein a condition index is generated by representing a bit matching the access condition by 1 and representing other bits by 0. Each attribute consists of a bit string that expresses an integer value of 1 or more and m or less in m bits, and among these m bits, the bit corresponding to the user attribute is 1, and the non-corresponding bit is a symbol representing an arbitrary character string Represented,
The user attribute information is information obtained by combining the bit strings of the attributes,
When performing access control with a plurality of attributes combined with an OR operator that matches the access conditions for a user having a plurality of attributes, the condition index generation means combines the bit strings of the plurality of attributes, For each attribute connected by the OR operator, a plurality of condition indexes are generated in which a bit that matches an access condition for one attribute is represented by 1 and other bits are represented by 0. The access control apparatus according to claim 1. An access control method for performing access control on specific data offline,
Each bit is represented by a bit string that expresses an integer value of 1 or more and m or less in m bits. Among the m bits, a bit corresponding to a user attribute is represented by 1 and a non-corresponding bit is represented by a symbol representing an arbitrary character string. A first step of generating one attribute key by processing attribute information of a user combined with a bit string of attributes with a secret key;
A second step of transmitting the generated attribute key to the user in advance;
When performing access control with a single attribute that matches the access condition for a user having a plurality of attributes, the bit strings of the plurality of attributes are combined and not used for the bit and access control that match the access condition. A third step of generating a conditional index with a bit string of attributes represented by 1 and the other bits represented by 0;
A fourth step of encrypting the specific data with information obtained by combining a key prepared in advance and the generated condition index;
A fifth step of encrypting, with a public key, information obtained by combining a key prepared in advance with the specific data and a condition index specifying a conditional expression in access control;
A sixth step of receiving the attribute key from a user when accessing specific data;
A seventh step of performing matching determination between the condition index and the received attribute key;
An eighth step of decrypting the information encrypted by the fifth step and outputting a decryption key when matching of the condition index and the attribute key is recognized by the seventh step; ,
An access control method comprising: An access control method for performing access control on specific data offline,
Each bit is represented by a bit string that expresses an integer value of 1 or more and m or less in m bits. Among the m bits, a bit corresponding to a user attribute is 1 and a non-corresponding bit is represented by a symbol representing an arbitrary character string. A first step of generating one attribute key by processing attribute information of a user combined with a bit string of attributes with a secret key;
A second step of transmitting the generated attribute key to the user in advance;
When access control is performed with a plurality of attributes combined with an AND operator that matches the access condition for a user having a plurality of attributes, the bit string that combines the bit strings of the plurality of attributes and matches the access condition A third step of generating a conditional index with 1 represented by 1 and the other bits represented by 0;
A fourth step of encrypting the specific data with information obtained by combining a key prepared in advance and the generated condition index;
A fifth step of encrypting, with a public key, information obtained by combining a key prepared in advance with the specific data and a condition index specifying a conditional expression in access control;
A sixth step of receiving the attribute key from a user when accessing specific data;
A seventh step of performing matching determination between the condition index and the received attribute key;
An eighth step of decrypting the information encrypted by the fifth step and outputting a decryption key when matching of the condition index and the attribute key is recognized by the seventh step; ,
An access control method comprising: An access control method for performing access control on specific data offline,
Each bit is represented by a bit string that expresses an integer value of 1 or more and m or less in m bits. Among the m bits, a bit corresponding to a user attribute is 1 and a non-corresponding bit is represented by a symbol representing an arbitrary character string. A first step of generating one attribute key by processing attribute information of a user combined with a bit string of attributes with a secret key;
A second step of transmitting the generated attribute key to the user in advance;
For users with multiple attributes, when performing access control with multiple attributes combined with an OR operator that matches the access conditions, the bit strings of the multiple attributes are combined and combined with the OR operator. For each attribute, a third step of generating a plurality of condition indexes in which a bit matching the access condition for one attribute is represented by 1 and the other bits are represented by 0;
A fourth step of encrypting the specific data with information obtained by combining a key prepared in advance and the generated condition index;
A fifth step of encrypting, with a public key, information obtained by combining a key prepared in advance with the specific data and a condition index specifying a conditional expression in access control;
A sixth step of receiving the attribute key from a user when accessing specific data;
A seventh step of performing matching determination between the condition index and the received attribute key;
An eighth step of decrypting the information encrypted by the fifth step and outputting a decryption key when matching of the condition index and the attribute key is recognized by the seventh step; ,
An access control method comprising: A program for performing offline access control for specific data using a computer,
Each bit is represented by a bit string that expresses an integer value of 1 or more and m or less in m bits. Among the m bits, a bit corresponding to a user attribute is represented by 1 and a non-corresponding bit is represented by a symbol representing an arbitrary character string. A first step of generating one attribute key by processing attribute information of a user combined with a bit string of attributes with a secret key;
A second step of transmitting the generated attribute key to the user in advance;
When performing access control with a single attribute that matches the access condition for a user having a plurality of attributes, the bit strings of the plurality of attributes are combined and not used for the bit and access control that match the access condition. A third step of generating a conditional index with a bit string of attributes represented by 1 and the other bits represented by 0;
A fourth step of encrypting the specific data with information obtained by combining a key prepared in advance and the generated condition index;
A fifth step of encrypting, with a public key, information obtained by combining a key prepared in advance with the specific data and a condition index specifying a conditional expression in access control;
A sixth step of receiving the attribute key from a user when accessing specific data;
A seventh step of performing matching determination between the condition index and the received attribute key;
An eighth step of decrypting the information encrypted by the fifth step and outputting a decryption key when matching of the condition index and the attribute key is recognized by the seventh step; ,
A program characterized by executing A program for performing offline access control for specific data using a computer,
Each bit is represented by a bit string that expresses an integer value of 1 or more and m or less in m bits. Among the m bits, a bit corresponding to a user attribute is represented by 1 and a non-corresponding bit is represented by a symbol representing an arbitrary character string. A first step of generating one attribute key by processing attribute information of a user combined with a bit string of attributes with a secret key;
A second step of transmitting the generated attribute key to the user in advance;
When access control is performed with a plurality of attributes combined with an AND operator that matches the access condition for a user having a plurality of attributes, the bit string that combines the bit strings of the plurality of attributes and matches the access condition A third step of generating a conditional index with 1 represented by 1 and the other bits represented by 0;
A fourth step of encrypting the specific data with information obtained by combining a key prepared in advance and the generated condition index;
A fifth step of encrypting, with a public key, information obtained by combining a key prepared in advance with the specific data and a condition index specifying a conditional expression in access control;
A sixth step of receiving the attribute key from a user when accessing specific data;
A seventh step of performing matching determination between the condition index and the received attribute key;
An eighth step of decrypting the information encrypted by the fifth step and outputting a decryption key when matching of the condition index and the attribute key is recognized by the seventh step; ,
A program characterized by executing A program for performing offline access control for specific data using a computer,
Each bit is represented by a bit string that expresses an integer value of 1 or more and m or less in m bits. Among the m bits, a bit corresponding to a user attribute is represented by 1 and a non-corresponding bit is represented by a symbol representing an arbitrary character string. A first step of generating one attribute key by processing attribute information of a user combined with a bit string of attributes with a secret key;
A second step of transmitting the generated attribute key to the user in advance;
For users with multiple attributes, when performing access control with multiple attributes combined with an OR operator that matches the access conditions, the bit strings of the multiple attributes are combined and combined with the OR operator. For each attribute, a third step of generating a plurality of condition indexes in which a bit matching the access condition for one attribute is represented by 1 and the other bits are represented by 0;
A fourth step of encrypting the specific data with information obtained by combining a key prepared in advance and the generated condition index;
A fifth step of encrypting, with a public key, information obtained by combining a key prepared in advance with the specific data and a condition index specifying a conditional expression in access control;
A sixth step of receiving the attribute key from a user when accessing specific data;
A seventh step of performing matching determination between the condition index and the received attribute key;
An eighth step of decrypting the information encrypted by the fifth step and outputting a decryption key when matching of the condition index and the attribute key is recognized by the seventh step; ,
A program characterized by executing

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