Private Set Membership Exchange for Asynchronous Mobile Apps

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Solution Overview

Problem

Existing mobile applications on a device cannot communicate directly for private set membership checks, raising privacy concerns and limiting data exchange capabilities, especially when they are not active simultaneously.

Innovation Solution

An enhanced cryptographic protocol enables private set membership checks between applications on the same device by using a service apparatus to store encrypted data, allowing asynchronous communication and ensuring that neither application learns information beyond the query result, without direct communication or shared private keys.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If applications communicate directly to enable private set membership checks, then data exchange capability is improved, but privacy security deteriorates as applications can learn information about users without consent

Engineering Contradiction:
Improvedata exchange capabilityVSAvoidprivacy leakage
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a server as an intermediary component that facilitates communication between applications without allowing them to directly exchange data. The server receives requests from the first application, performs private set membership checks using cryptographic protocols, and returns results without revealing underlying user information. This mediator approach enables data exchange capability while preventing privacy leakage by ensuring applications cannot learn information about users beyond the query results.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If applications use a server for communication to protect privacy, then privacy security is improved, but communication efficiency deteriorates when applications are not active simultaneously

Engineering Contradiction:
Improveprivacy protectionVSAvoidcommunication delay
Core Design Contradiction:
Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The patent implements preliminary action by allowing applications to pre-upload and pre-process data with the server before actual communication is needed. The first application can upload encrypted data sets to the server in advance, and the server can pre-compute cryptographic structures. When the second application needs to query, the server already has prepared data structures ready for rapid matching, significantly reducing communication delay while maintaining privacy protection through the server intermediary.

Inventive Principle:
Principle #10Preliminary action

3Stability of the object's composition

If applications share data storage to improve data synchronization, then data consistency is improved, but information security deteriorates as applications can access each other's stored information

Engineering Contradiction:
Improvedata synchronizationVSAvoidinformation exposure
Core Design Contradiction:
Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The patent applies the copying principle by creating encrypted copies of data sets that are stored and processed through the server intermediary. Instead of applications sharing direct access to the same storage, each application works with encrypted copies of the data. The server manages these copies and performs operations on them without revealing the underlying information to either application. This enables data synchronization through the server while preventing information exposure, as applications only receive query results rather than direct access to stored data.

Inventive Principle:
Principle #26Copying

Data Source

PatentEP4697220A1Secure data exchange
Publication Date: 2026.02.18 GOOGLE LLC
  • EP4697220A1 patent drawingFigure 1
  • EP4697220A1 patent drawingFigure 2
  • EP4697220A1 patent drawingFigure 3

AI summary

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for exchanging data in secure ways. In one aspect, a method includes sending, by a query app to a service apparatus, a first encrypted identifier generated by the query app and a first hashed identifier generated by the query app. A data app obtains, from the service apparatus, a set of encrypted identifiers that are mapped to hashed identifiers that match the first hashed identifier. For each of one or more values, the data app sends, to the service apparatus, a set of data that includes a second encrypted identifier, a respective encrypted value element that encrypts the value, and one or more first tuples. The query app obtains, from the service apparatus, one or more second tuples that are each mapped at the service apparatus to an encrypted identifier that matches the first encrypted identifier.