Searchable Encryption Using Position Information to Resist Frequency Analysis
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Solution Overview
Problem
Existing searchable encryption techniques with partial matching based on common-key cryptographic techniques like AES are vulnerable to frequency analysis attacks and face challenges in reducing data size and communication volume while maintaining security and functionality.
Innovation Solution
The proposed system enhances security by adding position information to character strings during encryption, making frequency analysis attacks more difficult, and optimizes data size and communication efficiency by using a method that generates unique ciphertexts for the same data each time, allowing for secure partial match searching without decrypting data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If data is partitioned into small pieces for partial match searching, then searching capability is improved, but vulnerability to frequency analysis attacks increases
Solution Approach 1:
The patent applies segmentation by dividing data into multiple pieces for partial match searching, while simultaneously using probabilistic encryption on each piece to prevent frequency analysis attacks. The data is partitioned into segments that can be independently encrypted and searched, maintaining both functionality and security.
Solution Approach 2:
The patent changes the encryption parameter from deterministic to probabilistic mode. This parameter change ensures that identical plaintext segments produce different ciphertexts each time, thereby eliminating the frequency patterns that vulnerability to frequency analysis attacks rely on while preserving the ability to perform partial match searches.
2Productivity
If deterministic encryption is used for partitioned data, then searching efficiency is improved, but security against frequency analysis attacks deteriorates
Solution Approach 1:
The patent introduces dynamics into the encryption process by using probabilistic encryption instead of deterministic encryption. This means the encryption behavior changes dynamically - identical inputs produce different outputs each time - which maintains searching efficiency through encrypted operations while improving security against frequency analysis attacks.
3Reliability
If data is encrypted and stored on server, then security is improved, but searching capability deteriorates
Solution Approach 1:
The patent introduces encrypted search indexes as an intermediary structure that enables searching without decryption. These indexes contain encrypted versions of search terms and their positions, acting as a mediator between the encrypted data storage and the searching capability, allowing both security and search functionality to coexist.
Solution Approach 2:
The patent creates encrypted copies of data segments and stores them in index structures that enable searching. Instead of decrypting the original data for searching, the system uses encrypted copies that preserve the searchability of the data while maintaining security through encryption.
Data Source
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AI summary
A data partition unit (305) partitions storage data D into N pieces of element data w1, w2, ..., wN from a front to an end of the character string data D. A partial character string generation unit (306) generates a set A = {A1, A2, ..., AN} and an element Ai = {(wi), (wiwi+1), ..., (wiwi+1 ... wN)} of the set A, where i = 1, ..., N, from the element data w1, w2, ..., wN. A position information assignment unit (307) generates a set B = {B1, B2, ..., BN} and an element Bi = {(i, wi), (i, wiwi+1), ..., (i, wiwi+1 ... wN)} of the set B by associating each of (wi), (wiwi+1), ..., (wiwi+1 ... wN) which are components of the element Ai with position information i. An encryption unit (308) encrypts each of (i, wi), (i, wiwi+1), ..., (i, wiwi+1 ... wN) which are components included in the element Bi.