Hybrid Searchable Encryption for Access Control and Speed

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Solution Overview

Problem

Current searchable encryption schemes cannot achieve access control while maintaining the speed of common-key searchable encryption schemes.

Innovation Solution

A system that includes a registration terminal generating a key and ciphertext for an access range, registering it with a key server, and generating tags for searching, which are registered with a search server, allowing for access control and high-speed search processes by using a common-key searchable encryption scheme.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If public-key searchable encryption scheme is used, then access control can be performed, but processing speed becomes slower

Engineering Contradiction:

Improveaccess control capabilityVSAvoidprocessing speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The patent divides the searchable encryption system into two separate components: a public-key encryption layer for access control and a common-key searchable encryption layer for fast searching. The public-key encryption is applied to encrypt the searchable encryption key, while the common-key encryption is used for the actual search tokens and data indexing, thus separating the access control function from the search function to achieve both security and speed.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary mechanism where a searchable encryption key is generated by common-key encryption and then encrypted by public-key encryption. This intermediary key structure allows the system to leverage the speed of common-key encryption for search operations while maintaining the access control capabilities of public-key encryption through the outer encryption layer.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If common-key searchable encryption scheme is used, then processing speed is faster, but access control cannot be performed

Engineering Contradiction:

Improveprocessing speedVSAvoidaccess control capability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent segments the encryption functions by applying common-key encryption specifically for generating search tokens and indexing, while using public-key encryption for key management and access control. This segmentation allows each encryption type to be used in the context where it performs best, achieving both speed and access control.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent creates a hybrid encryption system that combines the advantages of both public-key and common-key encryption schemes. The system universally supports both access control (through public-key encryption) and fast searching (through common-key encryption) within a single searchable encryption framework, making the system multi-functional.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11170123B2Registration terminal, key server, search system, and computer readable medium

Publication Date: 2021.11.09 MITSUBISHI ELECTRIC CORP

AI summary

A registration terminal registers a set of a key and a ciphertext in which an access range is set and in which the key K is encrypted in a key server, and registers a tag for searching generated from the key and a keyword for searching in a search server. A search terminal acquires a ciphertext in which an access range whose range for permitting access includes an attribute is set, and decrypts the ciphertext with a decryption key in which the attribute is set, so as to generate a key. The search terminal generates a trapdoor for searching from the key and a keyword for searching, and transmits the trapdoor to the search server to acquire data corresponding to the keyword.