JP2011198079A - System and method for encrypting database - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform high-speed exact match search with respect to a database storing probabilistically encrypted data, as well as partial match search with respect to a database storing encrypted data.SOLUTION: For high-speed exact match search with respect to the database storing probabilistically encrypted data, a definite encryption table and a ciphertext relation table that holds encrypted relation between tables are provided in addition to a probabilistic encryption table. The definite encryption table is searched, and the search result is converted by the ciphertext relation table, to obtain a result of search on the probabilistic encryption table. The database that stores encrypted data includes a definite encryption table which holds an index value for high-speed partial match search, and performs binary-research on a definite ciphertext based on the index value using the definite encryption table to narrow a range of the partial match search.

Description

  The present invention relates to a database encryption system for enhancing database security.

Data stored in the database is exposed to unauthorized removal by database administrators and SQL injection attacks by external unauthorized persons, and data leakage is a problem.
Therefore, as a database security measure, there is a database encryption system that encrypts data and stores it in the database.

FIG. 10 shows an example of a database in which data is decisively encrypted as described in Patent Document 1 and the like.
When the data is definitively encrypted, the same data is stored as the same ciphertext, and thus there is a problem that an unauthorized person knows that the same data exists between records.
FIG. 11 shows an example of a database in which data is stochastically encrypted.
When data is stochastically encrypted, even the same data is stored as different ciphertexts, so there is an advantage that an unauthorized person does not know that the data is the same between records.

  Note that stochastic encryption is performed by adding random numbers to data.

JP 2009-99151 A

When the data is definitively encrypted, the exact match search data can be encrypted and searched only once, so that the exact match search process can be performed at high speed. When the data is stochastically encrypted, the exact match search data is encrypted for each record and searched, so the exact match search process cannot be performed at high speed.
Therefore, a database in which data is stochastically encrypted has a problem that the exact match search process cannot be performed at high speed.

When data is encrypted, it is not possible to search for all complete match search data corresponding to partial match search data in an encrypted manner at high speed.
For example, when searching for data that begins with the partial match search string “AAA”, the enormous number of complete match search data from “AAAA ... A” to “AAAZ ... Z” is encrypted. This is virtually impossible.
Therefore, there is a problem that a partial match search process cannot be performed at high speed in a database in which data is encrypted.

  An object of the present invention is to perform database matching capable of performing a complete match search process at high speed even in a database in which data is stochastically encrypted, and capable of performing a partial match search process in a database at a high speed. It is to provide a system and method.

In order to achieve the above object, a system according to the present invention is configured by connecting a database server and an application server via a network, and the database of the database server includes a stochastic encryption table, a deterministic encryption table, and a ciphertext relationship table. And a database encryption system in which the database of the application server stores an encryption key,
In order to perform data registration processing in the database,
The application server includes means for performing stochastic encryption and deterministic encryption on data to be registered in the database, and transmitting the stochastic ciphertext 5 and the deterministic ciphertext to the database server,
After the database server inserts a record including a stochastic ciphertext and a stochastic cipher ID into the stochastic cipher table, and inserts a record including a deterministic ciphertext and a deterministic cipher ID into the deterministic cipher table, Means for transmitting a stochastic cryptographic ID and a definitive cryptographic ID to the application server;
The application server deterministically encrypts the stochastic cipher ID and the deterministic cipher ID with the cipher key obtained from the deterministic cipher text, and transmits the stochastic cipher ID cipher text and the definitive cipher ID cipher text to the database server. With means,
The database server includes means for inserting a record including a stochastic cipher ID ciphertext and a deterministic cipher ID ciphertext into the ciphertext relationship table.

In addition, as a data exact match search process of the database,
The application server is
Means for deterministically encrypting data and transmitting deterministic ciphertext to the database server;
The database server comprises means for projecting a definitive cipher ID from a record including a definitive ciphertext from the deterministic cipher table and transmitting the definitive cipher ID to the application server;
The application server comprises means for deterministically encrypting a definitive cipher ID with an encryption key obtained from the deterministic ciphertext and transmitting the definitive cipher ID ciphertext to the database server,
The database server includes means for projecting a stochastic cipher ID ciphertext from a record including a deterministic cipher ID ciphertext from the ciphertext relationship table and transmitting the stochastic cipher ID ciphertext to the application server;
The application server comprises means for deterministically decrypting a stochastic cipher ID ciphertext with an encryption key obtained from the deterministic ciphertext, and transmitting a stochastic cipher ID to the database server;
The database server includes means for selecting a record including a probabilistic encryption ID from the probabilistic encryption table and transmitting the record to the application server;
The application server projects the stochastic ciphertext from the record received from the database server, probabilistically decrypts the stochastic ciphertext, replaces the stochastic ciphertext of the record with plaintext, and obtains a record as a search result Means are provided.

In addition, as database data registration processing,
The database server comprises means for executing an index value registration process of the database with a definitive cipher ID and a definitive ciphertext as inputs,
Database partial match search processing of database,
The application server includes means for definitively encrypting search range start data and search range end data, and transmitting the search range start data ciphertext and search range end data ciphertext to the database server,
The database server executes index value acquisition processing of the database with a search range start data ciphertext as input, executes index value acquisition processing of the database with a search range end data ciphertext as input, and the deterministic encryption table Projecting the definitive cipher ID and the definitive ciphertext from the record whose index value is greater than or equal to the search range start index value and less than the search range end index value, and transmits the definitive cipher ID and definitive ciphertext to the application server With means,
If the application server deciphers the deterministic ciphertext and the plaintext sort order is between search range start data and search range end data, a deterministic cipher ID is obtained using the cipher key obtained from the deterministic ciphertext. Means for deterministically encrypting and transmitting a definitive cipher ID ciphertext to the database server,
The database server includes means for projecting a stochastic cipher ID ciphertext from a record including a deterministic cipher ID ciphertext from the ciphertext relationship table and transmitting the stochastic cipher ID ciphertext to the application server;
The application server comprises means for deterministically decrypting a stochastic cipher ID ciphertext with an encryption key obtained from the deterministic ciphertext, and transmitting a stochastic cipher ID to the database server;
The database server includes means for selecting a record including a probabilistic encryption ID from the probabilistic encryption table and transmitting the record to the application server;
The application server projects the stochastic ciphertext from the record received from the database server, probabilistically decrypts the stochastic ciphertext, replaces the stochastic ciphertext of the record with plaintext, and obtains a record as a search result It has the means to do, It is characterized by the above-mentioned.

The method according to the present invention is configured by connecting a database server and an application server via a network, and the database of the database server stores a stochastic encryption table, a deterministic encryption table, and a ciphertext relationship table, A database encryption method in which the database of the application server stores an encryption key,
In order to perform data registration processing in the database,
The application server comprises the steps of probabilistic encryption and deterministic encryption of data to be registered in the database, and transmitting the stochastic ciphertext 5 and deterministic ciphertext to the database server,
After the database server inserts a record including a stochastic ciphertext and a stochastic cipher ID into the stochastic cipher table, and inserts a record including a deterministic ciphertext and a deterministic cipher ID into the deterministic cipher table, Transmitting a stochastic cryptographic ID and a definitive cryptographic ID to the application server,
The application server deterministically encrypts the stochastic cipher ID and the deterministic cipher ID with the cipher key obtained from the deterministic cipher text, and transmits the stochastic cipher ID cipher text and the definitive cipher ID cipher text to the database server. With steps,
The database server includes a manual step of inserting a record including a stochastic cipher ID ciphertext and a deterministic cipher ID ciphertext into the ciphertext relation table.

In addition, as a data exact match search process of the database,
The application server is
Deterministically encrypting data and sending definitive ciphertext to the database server,
The database server includes projecting a definitive cipher ID from a record including definitive ciphertext from the deterministic cipher table and transmitting the definitive cipher ID to the application server;
The application server includes a step of definitively encrypting a definitive cipher ID with an encryption key obtained from the deterministic ciphertext and transmitting the definitive cipher ID ciphertext to the database server,
The database server includes a step of projecting a stochastic cipher ID ciphertext from a record including a definitive cipher ID ciphertext from the ciphertext relationship table, and transmitting the stochastic cipher ID ciphertext to the application server,
The application server deterministically decrypts a stochastic cipher ID ciphertext with an encryption key obtained from the deterministic ciphertext, and transmits the stochastic cipher ID to the database server,
The database server comprises selecting a record including a stochastic cipher ID from the stochastic cipher table and transmitting the record to the application server;
The application server projects the stochastic ciphertext from the record received from the database server, probabilistically decrypts the stochastic ciphertext, replaces the stochastic ciphertext of the record with plaintext, and obtains a record as a search result It is characterized by comprising a step.

In addition, as database data registration processing,
The database server includes a step of executing an index value registration process of the database with a definitive cipher ID and a definitive ciphertext as inputs,
Database partial match search processing of database,
The application server includes the step of definitively encrypting search range start data and search range end data, and transmitting the search range start data ciphertext and search range end data ciphertext to the database server,
The database server executes index value acquisition processing of the database with a search range start data ciphertext as input, executes index value acquisition processing of the database with a search range end data ciphertext as input, and the deterministic encryption table Projecting the definitive cipher ID and the definitive ciphertext from the record whose index value is greater than or equal to the search range start index value and less than the search range end index value, and transmits the definitive cipher ID and definitive ciphertext to the application server With steps,
If the application server deciphers the deterministic ciphertext and the plaintext sort order is between search range start data and search range end data, a deterministic cipher ID is obtained using the cipher key obtained from the deterministic ciphertext. Deciphering and sending a definitive cipher ID ciphertext to the database server,
The database server includes a step of projecting a stochastic cipher ID ciphertext from a record including a definitive cipher ID ciphertext from the ciphertext relationship table, and transmitting the stochastic cipher ID ciphertext to the application server,
The application server deterministically decrypts a stochastic cipher ID ciphertext with an encryption key obtained from the deterministic ciphertext, and transmits the stochastic cipher ID to the database server,
The database server comprises selecting a record including a stochastic cipher ID from the stochastic cipher table and transmitting the record to the application server;
The application server projects the stochastic ciphertext from the record received from the database server, probabilistically decrypts the stochastic ciphertext, replaces the stochastic ciphertext of the record with plaintext, and obtains a record as a search result The step which performs is characterized by the above-mentioned.

According to the present invention, in addition to the stochastic encryption table, a deterministic encryption table and a ciphertext relationship table that encrypts and holds the relationship between the two tables are provided, a search is performed using the deterministic encryption table, and the search result is encrypted. The search result in the probabilistic encryption table is acquired by converting the sentence relation table.
Thereby, even in a database in which data is stochastically encrypted, the exact match search process can be performed at high speed.
A deterministic encryption table that holds index values is provided, and the partial cipher search range is narrowed down by performing a binary search on the deterministic ciphertext based on the index values.
Thereby, even in a database in which data is encrypted, partial match search processing can be performed at high speed.
When the search result is converted in the ciphertext relationship table, the conversion of the search result relationship is guaranteed by the conversion using the encryption key acquired from the definitive ciphertext of the search result data.
Thereby, since an unauthorized person cannot convert arbitrary relations, it can be prevented that an unauthorized person is the same data between arbitrary records.

It is a figure which shows an example of a structure of the database encryption system of this invention. It is a figure which shows an example of the stochastic encryption table which a database server memorize | stores. It is a figure which shows an example of the definitive encryption table which a database server memorize | stores. It is a figure which shows an example of the ciphertext relationship table which a database server memorize | stores. It is a figure which shows an example of the data registration process of a database. It is a figure which shows an example of the index value registration process of a database. It is a figure which shows an example of the index value acquisition process of a database. It is a figure which shows an example of the data exact match search process of a database. It is a figure which shows an example of the data partial matching search process of a database. It is a figure which shows an example of the database which deciphered data. It is a figure which shows an example of the database which encrypted data stochastically.

Hereinafter, an example of the configuration of the database encryption system of the present invention will be described with reference to FIG.
In FIG. 1, the database encryption system of the present invention is configured by connecting a database server 1 and an application server 2 via a network 3.
The database server 1 is configured by connecting a central processing unit 4, a main storage device 6, an auxiliary storage device 8, and a network communication device 12 via a data bus 8.
The application server 2 includes a central processing unit 5, a main storage device 7, an auxiliary storage device 9, and a network communication device 13 connected via a data bus 11.
The auxiliary storage device 8 of the database server is provided with a probabilistic encryption table 81, a deterministic encryption table 82, and a ciphertext relationship table 83.
The auxiliary storage device 9 of the application server 2 is provided with a storage area 91 for the encryption key K.

Here, encryption used in the database encryption system of the present invention will be described.
The probabilistic encryption is a common key encryption having IV (initialization vector for encryption usage mode) or SALT (random bit string added to plaintext).
The probabilistic encryption processing PE receives the encryption key K and the plaintext M and outputs the ciphertext PE (K, M).
In the stochastic encryption process, even if the input is the same encryption key and plaintext, the output is different if the IV or SALT value is different.
Probabilistic decryption PD receives cipher key K and ciphertext C as inputs and outputs plaintext PD (K, C).
A deterministic cipher is a common key cipher without IV and SALT.
The definitive encryption process DE receives the encryption key K and the plaintext M, and outputs the ciphertext DE (K, M).
In the definitive encryption process, if the input is the same encryption key and plain text, the output is the same cipher text.
The definitive decryption process DD receives the encryption key K and the ciphertext C and outputs plaintext DD (K, C).
The keyed secure hash process H receives the encryption key K and the message M and outputs a secure hash value H (K, M).

For example, if the secure hash function is SHA-256 and the common key cipher is AES256 bits, the secure hash value and the encryption key have the same bit length, so the secure hash value can be used as the encryption key.
The application server 2 stores the encryption key K.

An example of the probabilistic encryption table 81 stored in the database server 1 will be described with reference to FIG.
The essential columns of the stochastic cipher table 81 are the stochastic cipher ID 811 and the stochastic ciphertext 812.
The probabilistic encryption ID 811 is a column with a unique constraint.
The stochastic cipher table 81 in FIG. 2 is a table in which a ciphertext obtained by probabilistically encrypting the name 812 and the card number 813 as a probabilistic ciphertext column and an age 814 as a personal information column are stored.
An example of the definitive encryption table 82 stored in the database server 1 will be described with reference to FIG.
The columns of the definitive cipher table 82 are definitive cipher ID 821, definitive ciphertext 822, and index value 823.
The definitive encryption ID 821 is a column with a unique constraint.

The deterministic cipher table 82 in FIG. 3 includes ciphertext obtained by definitively encrypting the name 822 and the card number 824 as the definitive ciphertext column, and a positive integer value in the ascending sort order of the name 822 and the card number 824 as the index value. It is a stored table.
An example of the ciphertext relationship table 83 stored in the database server 1 will be described with reference to FIG.
The columns of the ciphertext relationship table 83 are the probabilistic cipher ID ciphertext 831 and the deterministic cipher ID ciphertext 832.
The stochastic cipher ID ciphertext 831 is a ciphertext obtained by definitively encrypting the probabilistic cipher ID 811 of the stochastic cipher table 81.
The definitive cipher ID ciphertext 832 is a ciphertext obtained by definitively encrypting the definitive cipher ID 821 of the definitive cipher table 82.
An example of database data registration processing will be described with reference to FIG.
However, it is assumed that the application server 2 stores data M (for example, corresponding to a name or card number) and personal information (for example, corresponding to age).

In the example of FIG. 5, the table stored in the database server 1 is the state shown in FIGS. 2 to 4, and data registration processing is performed for data M (name = “HITACHI TARO”, card number = 1111222222222222) and personal information (age = 35). Is executed.
First, in step 501, the application server 2 executes the stochastic encryption process with the encryption key K and the data M as inputs, obtains the output stochastic ciphertext PC = PE (K, M), and The deterministic encryption process is executed with the encryption key K and the data M as inputs, the output deterministic ciphertext DC = DE (K, M) is obtained, and the database server 1 receives the probabilistic ciphertext 812 and The definitive ciphertext and personal information 822 are transmitted.

  In step 502, the database server 1 receives the stochastic ciphertext, deterministic ciphertext, and personal information from the application server 2, and randomly generates the stochastic cipher ID 811 so as to satisfy the unique constraint of the stochastic cipher table 81. Then, a record including the probabilistic cipher ID 811 generated in the probabilistic cipher table 81, the received probabilistic cipher text 812, and the personal information 814 is inserted, and the deterministic cipher text 822 received in the deterministic cipher table 82 is included. If a record is stored, step 503 is executed. If a record including the received definitive ciphertext 822 is not stored in the deterministic cipher table 82, step 504 is executed.

  In step 503, the database server 1 selects a record including the definitive ciphertext 822 received from the deterministic cipher table 82, projects (ie, extracts) the definitive cipher ID from the selected record, and then selects the application. The probabilistic encryption ID 811 generated and the projected deterministic encryption ID 821 are transmitted to the server 2, and step 504 is executed.

  In step 504, the database server 1 randomly generates a definitive cipher ID 821 so as to satisfy the unique constraint of the deterministic cipher table 82, and the definitive cipher ID 821 generated in the definitive cipher table 82 and the received definitive cipher A record including the sentence 822 is inserted, and the index value registration process of the database is executed with the generated deterministic cipher ID 821 and the received deterministic cipher text 822 as inputs, and the probabilistic cipher ID 811 generated in the application server 2 The definitive encryption ID 821 is transmitted and step 505 is executed.

  In step 505, the application server 2 receives the stochastic cipher ID 811 and the deterministic cipher ID 821 from the database server 1, executes the keyed secure hash process with the cipher key K and the definitive ciphertext DC as inputs, The output secure hash value KH = H (K, DC) is acquired, the deterministic encryption process is executed with the encryption key KH and the received probabilistic encryption ID as inputs, and the output probabilistic encryption ID The ciphertext DE (KH, probabilistic cipher ID) is acquired, the deterministic encryption process is executed with the cipher key KH and the received deterministic cipher ID as inputs, and the output deterministic cipher ID cipher text DE (KH, deterministic cipher ID) is acquired, and the stochastic cipher ID ciphertext and the definitive cipher ID ciphertext are transmitted to the database server 1.

In step 506, the database server 1
The probabilistic cipher ID ciphertext and deterministic cipher ID ciphertext are received from the application server 2 and a record including the received probabilistic cipher ID ciphertext and deterministic cipher ID ciphertext is inserted into the ciphertext relationship table 83.
An example of database index value registration processing will be described with reference to FIG.
However, a definitive cipher ID and a definitive ciphertext are input.

The example of FIG. 6 is a case where the index value registration process is executed in step 504 of FIG. 5 with the definitive cipher ID = DIDC981 and the definitive ciphertext = DE (K, 1111222222222222) as inputs.
In step 601, the database server 1 executes the database index value acquisition process with deterministic ciphertext as input, and acquires the output registered index value.

  In step 602, the database server 1 selects a record whose index value is equal to or greater than the registered index value from the deterministic encryption table 82, and increments and updates the index value of the selected record.

  In step 603, the database server 1 selects a record including the deterministic encryption ID 821 from the deterministic encryption table 82, and updates the index value of the selected record to the registered index value.

An example of database index value acquisition processing will be described with reference to FIG.
However, the definitive ciphertext is input and the index value is output.
In step 701, if there is no record in the definitive encryption table 82, the database server 1 sets the output index value to 1 and executes step 707.
In step 702, the database server 1 acquires the maximum index value from the deterministic encryption table 82, sets the lower limit index value to 1, and sets the upper limit index value as the maximum index value acquired.

  In step 703, if the lower limit index value is less than or equal to the upper limit index value, the database server 1 sets the central index value as an average integer value of the lower limit index value and the upper limit index value, and if the lower limit index value is greater than the upper limit index value, Step 707 is executed with the output index value as the lower limit index value.

  In step 704, the database server 1 selects a record including the central index value from the deterministic cipher table 82, projects the definitive ciphertext 822 from the selected record, and inputs the deterministic ciphertext to the application server 2. Send the projected central definitive ciphertext.

In step 705, the application server 2 receives the input deterministic ciphertext and the central deterministic ciphertext from the database server 1, and executes the deterministic decryption process with the encryption key K and the input deterministic ciphertext as inputs. , The output input plaintext = DD (K, input deterministic ciphertext) is obtained, the deterministic decryption process is executed with the encryption key K and the central deterministic ciphertext as inputs, and the output central plaintext = DD (K, central deterministic ciphertext) is obtained, the sort order of the input plaintext and the central plaintext is compared, and “same plaintext” or “ascending order” or “descending order” is obtained as the sort order comparison result, The sort order comparison result is transmitted to the database server 1.
Here, the input deterministic ciphertext is a ciphertext of a value to be searched in the binary search, and the central deterministic ciphertext is a ciphertext of the central value in the binary search.

For example, if the plain text is a string,
Sort order comparison result of input plaintext “ABC” and central plaintext “ABC” is “same plaintext”
Sort order comparison result of input plaintext “ABC” and central plaintext “ACC” is “ascending order”,
The sort order comparison result between the input plaintext “ABC” and the central plaintext “ABB” is “descending order”.
For example, if the plain text is numeric,
Sort order comparison result of input plaintext “1000” and central plaintext “1000” is “same plaintext”
The sort order comparison result of input plaintext “1000” and central plaintext “1001” is “ascending order”,
The sort order comparison result between the input plaintext “1000” and the central plaintext “999” is “descending order”.
In step 706, the database server 1 receives the sort order comparison result from the application server 2, and if the sort order comparison result is “same plaintext”, the output index value is set as the central index value and the sort is performed by executing step 707. If the order comparison result is “ascending order”, the upper limit index value is set to the central index value−1, and step 703 is executed. If the sort order comparison result is “descending order”, the lower limit index value is set to the central index value + 1. 703 is executed.

In step 707, the database server 1 outputs the output index value.
An example of database index value acquisition processing will be described in the case of executing decipher ciphertext = DE (K, 1111222222222222) as input in step 601 of FIG.
In step 701, nothing is executed in step 701 because there is a record in the definitive encryption table.

In the second step, in step 702, the lower limit index value = 1 and the upper limit index value = 3.
In the third step, since the lower limit index value 1 ≦ the upper limit index value 3 in step 703, the central index value = (lower limit index value 1 + upper limit index value 3) / 2 = 2.
In step 704, the input deterministic ciphertext = DE (K, 1111222222222222) and the central deterministic ciphertext = DE (K, 1111333333333333) are transmitted in the fourth step.

In step 705, the sort order of input plaintext = 111122222222222222 and central plaintext = 1111333333333333 is compared in step 705, and the sort order comparison result “ascending order” is transmitted.
In the sixth step, since the sorting order comparison result is “ascending order” in step 706, upper limit index value = center index value 2-1 = 1.
In the seventh step, in step 703, since lower limit index value 1 ≦ upper limit index value 1, the central index value = (lower limit index value 1 + upper limit index value 1) / 2 = 1.

In step 704, the input deterministic ciphertext = DE (K, 1111222222222222) and the central deterministic ciphertext = DE (K, 1111111111111111) are transmitted in the eighth step.
In step 705, the sort order of input plaintext = 1111222222222222 and central plaintext = 1111111111111111 is compared in step 705, and the sort order comparison result “descending order” is transmitted.
In the tenth step, since the sorting order comparison result is “descending order” in step 706, the lower limit index value = the central index value 1 + 1 = 2.
In the eleventh step, since the lower limit index value 2> the upper limit index value 1 in step 703, output index value = lower limit index value 2.
In the twelfth step, in step 707, the output index value 2 is output.

An example of the database complete match search process will be described with reference to FIG.
However, it is assumed that the application server 2 stores data M (for example, corresponding to a name or a card number).
The example of FIG. 8 is a case where the table stored in the database server 1 is in the state of FIGS. 2 to 4 and the data exact match search process is executed for the data M (name = “HITACHI TARO”).
In step 801, the application server 2 executes the definitive encryption process with the encryption key K and the data M as inputs, obtains the output deterministic ciphertext DC = DE (K, M), and creates a database. A definitive ciphertext is transmitted to the server 1.

  In step 802, the database server 1 receives the definitive ciphertext from the application server 2, selects a record including the definitive ciphertext received from the deterministic cipher table 82, and determines the deterministic cipher ID 821 from the selected record. And the deterministic encryption ID 821 projected to the application server 2 is transmitted.

In step 803, the application server 2 receives the definitive cipher ID 821 from the database server 1, executes the keyed secure hash process with the cipher key K and the deterministic ciphertext DC as inputs, and outputs the output secure hash The value KH = H (K, DC) is acquired, and the deterministic encryption process is executed with the cipher key KH and the received deterministic cipher ID 821 as inputs, and the output deterministic cipher ID ciphertext DE (KH) , Deterministic encryption ID)
The definitive cipher ID ciphertext 822 is transmitted to the database server 1.

  In step 804, the database server 1 receives the definitive cipher ID ciphertext from the application server 2, selects a record including the definitive cipher ID ciphertext received from the ciphertext relationship table 83, and selects the record from the selected record. The probabilistic cipher ID ciphertext is projected and the projected probabilistic cipher ID ciphertext is transmitted to the application server 2.

  In step 805, the application server 2 receives the stochastic cipher ID ciphertext from the database server 1, executes the keyed secure hash process with the cipher key K and the deterministic ciphertext DC as inputs, and outputs The secure hash value KH = H (K, DC) is acquired, and the deterministic decryption process is executed with the encryption key KH and the received probabilistic cipher ID ciphertext as input, and the output probabilistic cipher ID = DD (KH, stochastic cipher ID ciphertext) is acquired, and the stochastic cipher ID is transmitted to the database server 1.

  In step 806, the database server 1 receives the stochastic encryption ID from the application server 2, selects a record including the stochastic encryption ID 811 received from the stochastic encryption table 81, and selects the record selected by the application server 2. Send.

  In step 807, the application server 2 receives the record from the database server 1, projects the probabilistic ciphertext from the received record, and inputs the stochastic ciphertext obtained by projecting the probabilistic decryption process with the encryption key K. Is executed, and the output plaintext M = PD (K, stochastic ciphertext) is obtained, the stochastic ciphertext of the received record is replaced with plaintext M, and the search result of the data exact match search process Get a record.

Next, an example of the data partial match search process in the database will be described with reference to FIG. However, it is assumed that the application server 2 stores search range start data M1 and search range end data M2 (e.g., corresponding to a name and a card number).
In the example of FIG. 9, the table stored in the database server 1 is in the state shown in FIGS. 2 to 4, and the data partial match between the search range start data M1 (card number = 1000000000000000) and the search range end data M2 (card number = 2000000000000000) This is a case where search processing is executed.
The data partial match search is a character string forward match search when the data is a character string, and is a value range search when the data is a numerical value.

For example, when searching for data starting from the character string “AAA”, the search range start data M1 is “AAA”, the search range end data M2 is “AAB”, and data with a numerical value “1000” or more and less than “2000” is searched. In this case, the search range start data M1 is “1000” and the search range end data M2 is “2000”.
In step 901, the application server 2 executes the definitive encryption process with the encryption key K and the search range start data M1 as inputs, and outputs the output search range start data ciphertext DC1 = DE (K, M1). Obtaining and executing the definitive encryption processing with the encryption key K and the search range end data M2 as inputs, and obtaining the output search range end data ciphertext DC2 = DE (K, M2) The search range start data ciphertext and the search range end data ciphertext are transmitted to the server 1.

  In step 902, the database server 1 receives the search range start data ciphertext and the search range end data ciphertext from the application server 2, and executes the index value acquisition processing of the database with the search range start data ciphertext as input. Obtain the output search range start index value, execute the database index value acquisition process with the search range end data ciphertext as input, acquire the output search range end index value, and decide A record whose index value is greater than or equal to the search range start index value and less than the search range end index value is selected from the dynamic encryption table, and step 903 and subsequent steps are executed for each selected record.

In step 903, the database server 1 projects the definitive cipher ID 821 and the definitive ciphertext 822 from the selected record, and transmits the definitive cipher ID 821 and the definitive ciphertext 822 projected to the application server 2.
In step 904, the application server 2 receives the deterministic cipher ID 821 and the definitive ciphertext DC from the database server 1, and executes the definitive decryption process with the cipher key K and the received definitive ciphertext DC as inputs. The output plaintext M = PD (K, DC) is acquired, the search range start data M1 is compared with the sort order of the plaintext M, and “same plaintext” or “ascending order” is acquired as the sort order comparison result. If the sort order of the plaintext M and the search range end data M2 is compared and “ascending order” is acquired as the sort order comparison result, the keyed secure hash process is received as the encryption key K. The encrypted ciphertext DC is executed as an input, the output secure hash value KH = H (K, DC) is obtained, and the definitive encryption process is received with the encryption key KH. Run the cryptography ID as input and output a deterministic cipher ID ciphertext DE (KH, deterministic cipher ID) to obtain the transmit deterministic cipher ID ciphertext database server 1.

  In step 905, the database server 1 receives the definitive cipher ID ciphertext from the application server 2, selects a record including the definitive cipher ID ciphertext received from the ciphertext relationship table 83, and selects the record from the selected record. The probabilistic cipher ID ciphertext is projected and the projected probabilistic cipher ID ciphertext is transmitted to the application server 2.

  In step 906, the application server 2 receives the probabilistic cipher ID ciphertext from the database server 1, executes the keyed secure hash process with the cipher key K and the deterministic ciphertext DC as inputs, and outputs the result. The secure hash value KH = H (K, DC) is acquired, and the deterministic decryption process is executed with the encryption key KH and the received probabilistic cipher ID ciphertext as input, and the output probabilistic cipher ID = DD (KH, stochastic cipher ID ciphertext) is acquired, and the stochastic cipher ID is transmitted to the database server 1.

In step 907, the database server 1 receives the stochastic encryption ID from the application server 2, selects the record including the stochastic encryption ID 811 received from the stochastic encryption table 81, and selects the record selected by the application server 2. Send.
In step 908, the application server 2 receives the record from the database server 1, projects the probabilistic ciphertext from the received record, and inputs the probabilistic ciphertext obtained by projecting the probabilistic decryption process with the encryption key K. As the search result of the data partial match search process, the output plaintext M = PD (K, stochastic ciphertext) is obtained, the stochastic ciphertext of the received record is replaced with plaintext M, Get a record.

DESCRIPTION OF SYMBOLS 1 Database server 2 Application server 3 Network 4, 5 Central processing unit 6,7 Main storage unit 8,9 Auxiliary storage unit 12,13 Network communication unit 10,11 Data bus 81 Probabilistic encryption table 82 Deterministic encryption table 83 Encryption Sentence relation table

Claims (6)

A database server and an application server are connected via a network, the database server database stores a stochastic encryption table, a deterministic encryption table, and a ciphertext relationship table, and the application server database stores an encryption key. A database encryption system for storing,
In order to perform data registration processing in the database,
The application server includes means for performing stochastic encryption and deterministic encryption on data to be registered in the database, and transmitting the stochastic ciphertext 5 and the deterministic ciphertext to the database server,
After the database server inserts a record including a stochastic ciphertext and a stochastic cipher ID into the stochastic cipher table, and inserts a record including a deterministic ciphertext and a deterministic cipher ID into the deterministic cipher table, Means for transmitting a stochastic cryptographic ID and a definitive cryptographic ID to the application server;
The application server deterministically encrypts the stochastic cipher ID and the deterministic cipher ID with the cipher key obtained from the deterministic cipher text, and transmits the stochastic cipher ID cipher text and the definitive cipher ID cipher text to the database server. With means,
The database encryption system, wherein the database server comprises means for inserting a record including a stochastic cipher ID ciphertext and a deterministic cipher ID ciphertext into the ciphertext relationship table. As the data exact match search processing of the database,
The application server is
Means for deterministically encrypting data and transmitting deterministic ciphertext to the database server;
The database server comprises means for projecting a definitive cipher ID from a record including a definitive ciphertext from the deterministic cipher table and transmitting the definitive cipher ID to the application server;
The application server comprises means for deterministically encrypting a definitive cipher ID with an encryption key obtained from the deterministic ciphertext and transmitting the definitive cipher ID ciphertext to the database server,
The database server includes means for projecting a stochastic cipher ID ciphertext from a record including a deterministic cipher ID ciphertext from the ciphertext relationship table and transmitting the stochastic cipher ID ciphertext to the application server;
The application server comprises means for deterministically decrypting a stochastic cipher ID ciphertext with an encryption key obtained from the deterministic ciphertext, and transmitting a stochastic cipher ID to the database server;
The database server includes means for selecting a record including a probabilistic encryption ID from the probabilistic encryption table and transmitting the record to the application server;
The application server projects the stochastic ciphertext from the record received from the database server, probabilistically decrypts the stochastic ciphertext, replaces the stochastic ciphertext of the record with plaintext, and obtains a record as a search result The database encryption system according to claim 1, further comprising means. As database data registration processing,
The database server comprises means for executing an index value registration process of the database with a definitive cipher ID and a definitive ciphertext as inputs,
Database partial match search processing of database,
The application server includes means for definitively encrypting search range start data and search range end data, and transmitting the search range start data ciphertext and search range end data ciphertext to the database server,
The database server executes index value acquisition processing of the database with a search range start data ciphertext as input, executes index value acquisition processing of the database with a search range end data ciphertext as input, and the deterministic encryption table Projecting the definitive cipher ID and the definitive ciphertext from the record whose index value is greater than or equal to the search range start index value and less than the search range end index value, and transmits the definitive cipher ID and definitive ciphertext to the application server With means,
If the application server deciphers the deterministic ciphertext and the plaintext sort order is between search range start data and search range end data, a deterministic cipher ID is obtained using the cipher key obtained from the deterministic ciphertext. Means for deterministically encrypting and transmitting a definitive cipher ID ciphertext to the database server,
The database server includes means for projecting a stochastic cipher ID ciphertext from a record including a deterministic cipher ID ciphertext from the ciphertext relationship table and transmitting the stochastic cipher ID ciphertext to the application server;
The application server comprises means for deterministically decrypting a stochastic cipher ID ciphertext with an encryption key obtained from the deterministic ciphertext, and transmitting a stochastic cipher ID to the database server;
The database server includes means for selecting a record including a probabilistic encryption ID from the probabilistic encryption table and transmitting the record to the application server;
The application server projects the stochastic ciphertext from the record received from the database server, probabilistically decrypts the stochastic ciphertext, replaces the stochastic ciphertext of the record with plaintext, and obtains a record as a search result The database encryption system according to claim 1, further comprising: A database server and an application server are connected via a network, the database server database stores a stochastic encryption table, a deterministic encryption table, and a ciphertext relationship table, and the application server database stores an encryption key. A database encryption method for storing,
In order to perform data registration processing in the database,
The application server comprises the steps of probabilistic encryption and deterministic encryption of data to be registered in the database, and transmitting the stochastic ciphertext 5 and deterministic ciphertext to the database server,
After the database server inserts a record including a stochastic ciphertext and a stochastic cipher ID into the stochastic cipher table, and inserts a record including a deterministic ciphertext and a deterministic cipher ID into the deterministic cipher table, Transmitting a stochastic cryptographic ID and a definitive cryptographic ID to the application server,
The application server deterministically encrypts the stochastic cipher ID and the deterministic cipher ID with the cipher key obtained from the deterministic cipher text, and transmits the stochastic cipher ID cipher text and the definitive cipher ID cipher text to the database server. With steps,
The database encryption method, wherein the database server comprises a manual step of inserting a record including a stochastic cipher ID ciphertext and a definitive cipher ID ciphertext into the ciphertext relationship table. As the data exact match search processing of the database,
The application server is
Deterministically encrypting data and sending definitive ciphertext to the database server,
The database server includes projecting a definitive cipher ID from a record including definitive ciphertext from the deterministic cipher table and transmitting the definitive cipher ID to the application server;
The application server includes a step of definitively encrypting a definitive cipher ID with an encryption key obtained from the deterministic ciphertext and transmitting the definitive cipher ID ciphertext to the database server,
The database server includes a step of projecting a stochastic cipher ID ciphertext from a record including a definitive cipher ID ciphertext from the ciphertext relationship table, and transmitting the stochastic cipher ID ciphertext to the application server,
The application server deterministically decrypts a stochastic cipher ID ciphertext with an encryption key obtained from the deterministic ciphertext, and transmits the stochastic cipher ID to the database server,
The database server comprises selecting a record including a stochastic cipher ID from the stochastic cipher table and transmitting the record to the application server;
The application server projects the stochastic ciphertext from the record received from the database server, probabilistically decrypts the stochastic ciphertext, replaces the stochastic ciphertext of the record with plaintext, and obtains a record as a search result The database encryption method according to claim 4, further comprising a step. As database data registration processing,
The database server includes a step of executing an index value registration process of the database with a definitive cipher ID and a definitive ciphertext as inputs,
Database partial match search processing of database,
The application server includes the step of definitively encrypting search range start data and search range end data, and transmitting the search range start data ciphertext and search range end data ciphertext to the database server,
The database server executes index value acquisition processing of the database with a search range start data ciphertext as input, executes index value acquisition processing of the database with a search range end data ciphertext as input, and the deterministic encryption table Projecting the definitive cipher ID and the definitive ciphertext from the record whose index value is greater than or equal to the search range start index value and less than the search range end index value, and transmits the definitive cipher ID and definitive ciphertext to the application server With steps,
If the application server deciphers the deterministic ciphertext and the plaintext sort order is between search range start data and search range end data, a deterministic cipher ID is obtained using the cipher key obtained from the deterministic ciphertext. Deciphering and sending a definitive cipher ID ciphertext to the database server,
The database server includes a step of projecting a stochastic cipher ID ciphertext from a record including a definitive cipher ID ciphertext from the ciphertext relationship table, and transmitting the stochastic cipher ID ciphertext to the application server,
The application server deterministically decrypts a stochastic cipher ID ciphertext with an encryption key obtained from the deterministic ciphertext, and transmits the stochastic cipher ID to the database server,
The database server comprises selecting a record including a stochastic cipher ID from the stochastic cipher table and transmitting the record to the application server;
The application server projects the stochastic ciphertext from the record received from the database server, probabilistically decrypts the stochastic ciphertext, replaces the stochastic ciphertext of the record with plaintext, and obtains a record as a search result The database encryption method according to claim 1, further comprising the step of:

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