RELATIONAL DATABASE, INDEX TABLE GENERATION METHOD IN THE RELATIONAL DATABASE, AND RANGE SEARCH METHOD AND RANK SEARCH METHOD FOR ITS RANGE SEARCH IN THE RELATIONAL DATABASE

摘要

PROBLEM TO BE SOLVED: To provide a relational database in which confidentiality of a database file is secured if wrong doing is tried by a hacker and the like and a period of time required for searching the database file by a legitimate user does not increase so remarkably.

SOLUTION: The relational database is constituted with an encryption table and an index table. The encryption table is what a plain text table is encrypted on item by item basis. The index table is the table in which each item in the plain text table is sorted, a rank for the each item is generated and the rank is defined as an item value for the corresponding item. The each item in the index table corresponds with the each item in the encryption table. A binary search can be performed quickly because the rank of the item can be captured by referring to the index table without generating the plain text table by decoding a whole of the encryption table in performing range search for this relational database.

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