Registration Destination Determination for Searchable Encryption

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In searchable encryption systems, deterministic encryption schemes are vulnerable to frequency analysis attacks due to the uniformity of keyword frequency distribution, while probabilistic encryption schemes increase communication overhead and retrieval time, and existing solutions fail to prevent frequency information leakage over time.

Innovation Solution

A registration destination determination device is implemented to manage registration data across multiple data management devices, ensuring that the appearance frequency distribution of values differs across each device, making it difficult for the data management device to estimate the registration data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If deterministic encryption is used, then retrieval speed is improved, but security deteriorates due to frequency analysis attacks

Engineering Contradiction:

Improveretrieval speedVSAvoidsecurity

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent segments the frequency distribution of encrypted keywords across multiple data management devices. Instead of one device holding all data with uniform frequency distribution, the system divides data storage across multiple devices such that each device holds only a portion of the total data. This segmentation prevents any single device from observing the complete frequency distribution, thereby maintaining security while allowing fast deterministic retrieval within each device's local data set.

Inventive Principle:

Principle #1Segmentation

2Reliability

If probabilistic encryption is used, then security is improved, but retrieval time increases

Engineering Contradiction:

ImprovesecurityVSAvoidretrieval time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies local quality by making each data management device use deterministic encryption locally for fast retrieval operations. Each device maintains its own deterministic encryption scheme optimized for speed. The security enhancement comes from the global distribution effect across multiple devices rather than from probabilistic encryption at the local level, thus achieving fast retrieval without sacrificing security.

Inventive Principle:

Principle #3Local quality

3Reliability

If retrieval conditions are widened to prevent frequency analysis, then security is improved, but communication overhead increases

Engineering Contradiction:

ImprovesecurityVSAvoidcommunication overhead

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The patent extracts the frequency distribution information from the local view of each data management device by distributing data across multiple devices. Each device only observes a subset of the total frequency distribution, so the harmful frequency analysis capability is extracted away from any single device. This allows each device to maintain precise retrieval conditions without excessive communication overhead, as the security comes from the collective distribution rather than widened search conditions.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS10936757B2Registration destination determination device, searchable encryption system, destination determination method, and computer readable medium

Publication Date: 2021.03.02 MITSUBISHI ELECTRIC CORP

AI summary

A registration destination determination device (50) determines which data management device, among a plurality of data management devices (20A, 20B), is to manage registration data, such that, with a data type constituting the registration data as a target type, an appearance frequency distribution of values set for the target type of the registration data managed by each of the plurality of data management devices (20A, 20B) is different from an appearance frequency distribution of values set for the target type of the registration data managed by the whole of the plurality of data management devices (20A, 20B).