Private Set Intersection Using Homomorphic Encryption

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Solution Overview

Problem

Conventional private set intersection techniques are inefficient due to the large amount of ciphertext information exchanged, leading to high communication bandwidth and storage requirements, especially when dealing with data strings exceeding 32 bits.

Innovation Solution

The described techniques use homomorphic encryption to segment data into strings, encrypt them individually or collectively, and use a server to create a ciphertext vector by multiplying with a matrix, allowing entities to determine common data strings without revealing other data strings, thus reducing communication bandwidth and storage needs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional private set intersection techniques are used to encrypt and exchange data strings, then data privacy is protected, but communication bandwidth and storage requirements increase significantly

Engineering Contradiction:
Improvedata privacy protectionVSAvoidciphertext information volume
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent segments data strings into fixed 32-bit blocks and processes them in batches. Instead of encrypting and exchanging entire large data strings individually, the system divides them into smaller segments that can be handled more efficiently, reducing the overall ciphertext volume while maintaining privacy protection

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the encryption approach by using homomorphic encryption properties to perform set intersection operations directly on encrypted data without full decryption. This parameter change in the cryptographic approach reduces the amount of ciphertext that needs to be exchanged and stored compared to conventional encryption methods

Inventive Principle:
Principle #35Parameter changes

2Reliability

If conventional private set intersection techniques encrypt data strings exceeding 32 bits, then data privacy is maintained, but processing efficiency and communication speed deteriorate

Engineering Contradiction:
Improvedata privacyVSAvoidintersection calculation speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent segments data strings exceeding 32 bits into multiple fixed-size blocks and processes them in batches. This segmentation allows the system to handle large data strings efficiently by breaking them down into manageable units that can be processed faster while maintaining the same privacy protection level

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses batch processing where multiple encrypted data blocks are processed together in a single homomorphic encryption operation. This partial action approach processes groups of data segments simultaneously rather than individually, significantly improving processing efficiency while maintaining complete privacy protection

Inventive Principle:
Principle #16Partial or excessive action

3Productivity

If conventional private set intersection techniques are used, then entities can find common data elements, but communication bandwidth consumption increases due to large encrypted payloads

Engineering Contradiction:
Improveset intersection capabilityVSAvoidcommunication bandwidth usage
Core Design Contradiction:
ProductivityVSQuantity of substance

Solution Approach 1:

The patent merges multiple encrypted data blocks into batched homomorphic encryption operations. By combining multiple data segments into single cryptographic operations, the system reduces the total number of separate ciphertext transmissions required, thereby reducing communication bandwidth consumption while maintaining the ability to find common elements

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent changes the cryptographic parameter approach by using homomorphic encryption schemes that allow set intersection operations to be performed on encrypted data with reduced communication overhead. This parameter change enables the system to maintain full set intersection capability while significantly reducing the bandwidth required for exchanging encrypted payloads

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS10608811B2Private set intersection encryption techniques
Publication Date: 2020.03.31 MICROSOFT TECHNOLOGY LICENSING LLC
  • US10608811B2 patent drawing
  • US10608811B2 patent drawing
  • US10608811B2 patent drawing

AI summary

The disclosure herein relates to private set intersection techniques. The described private set intersection techniques enable entities to determine common data strings in their respective data sets. The private set intersection techniques described herein allow those common data strings to be shareable between the entities, while maintaining the secrecy of other data strings stored in their respective data sets.