Secure Wildcard Retrieval System Using Polynomial Matching

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing secure computation techniques for match retrieval with wildcard characters in databases are inefficient, requiring high communication volume of O(N^2 / log N) when concealing search words and search targets, which hinders effective data retrieval.

Innovation Solution

The proposed solution involves a retrieval system that uses secure computation methods, including equality determination, wildcard determination, and OR operations to efficiently match concealed search words with concealed database entries, reducing communication volume to O(N) by concealing search words and search targets using secret sharing or homomorphic cryptosystems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If secure computation techniques are used to perform match retrieval with wildcard characters while concealing search words and search targets, then data privacy is maintained, but communication volume increases to O(N^2 / log N)

Engineering Contradiction:
Improvedata privacyVSAvoidcommunication volume
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent divides the search word into multiple segments corresponding to different wildcard patterns. Each segment is processed separately through secure computation, allowing the system to handle wildcard matching in a distributed manner. This segmentation reduces the overall communication complexity from O(N^2 / log N) to O(N) by breaking down the monolithic secure computation into smaller, more efficient operations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transforms the wildcard matching problem from a direct character-by-character comparison into a polynomial-based computational framework. By representing search patterns as polynomials and using homomorphic encryption, the system operates in a mathematical dimension rather than a textual dimension, enabling efficient secure computation with reduced communication overhead.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If wildcard character matching is implemented in concealed databases, then search flexibility is improved, but computation complexity increases

Engineering Contradiction:
Improvesearch flexibilityVSAvoidcomputation complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent changes the parameter representation from direct character matching to polynomial coefficient matching. Wildcard patterns are encoded as polynomial parameters that can be efficiently compared using homomorphic encryption operations. This parameter transformation maintains search flexibility while reducing computation complexity by leveraging mathematical properties of polynomial arithmetic.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical character-by-character comparison mechanism with a mathematical polynomial-based system. Instead of iteratively comparing each character position, the system uses polynomial multiplication and evaluation under homomorphic encryption, which substitutes complex iterative computation with more efficient algebraic operations.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP3731215B1Retrieval device, retrieval method, program, and recording medium
Publication Date: 2024.02.07 NIPPON TELEGRAPH & TELEPHONE CORP
  • EP3731215B1 patent drawingFigure 1
  • EP3731215B1 patent drawingFigure 2
  • EP3731215B1 patent drawingFigure 3

AI summary

An equality determination unit obtains [ei] in which ei = (ei,1, ..., ei,N) is concealed, ei in which ei,j = a1 is established when xi,j is kj and ei,j = a0 is established when xi,j is not kj, by secure computation using a concealed search target word [xi] and a concealed search word [k]. A wildcard determination unit obtains [w] in which w = (w1, ..., wN) is concealed, w in which wj = b1 is established when kj is a wildcard character and wj = b0 is established when kj is not a wildcard character, by secure computation using [k]. An OR operation unit obtains [yi] in which yi = (yi,1, ..., yi,N) is concealed, yi in which yi,j = d1 is established when at least one of ei,j = a1 and wj = b1 is satisfied and yi,j = d0 is established when at least one of ei,j = a1 and wj = b1 is not satisfied, by secure computation using [ei] and [w].