Secure Multi-Party Extremum Search With Mean-Based Node Filtering

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Solution Overview

Problem

Existing secure multi-party computation methods for determining an extremum face high computation complexity and communication overhead, especially in multi-party scenarios, making them inefficient for cross-network communication applications.

Innovation Solution

A method involving federated computation systems where node devices compare their data with progressively decreasing means, replacing data less than the mean with invalid data to converge on the extremum, reducing the need for encryption and decryption operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If oblivious transfer technology is used for multi-party data comparison, then data security is maintained, but communication overhead increases and efficiency decreases

Engineering Contradiction:
Improvedata securityVSAvoidcomputation efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent segments the multi-party comparison problem into multiple rounds of computation, where in each round only a subset of parties actively compare their data. This reduces the communication overhead from O(n²) to O(n) per round, while maintaining security through the secure comparison protocol. The segmentation of computation rounds allows the system to scale to more parties without quadratic communication costs.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a filtering mechanism that performs preliminary actions by identifying and eliminating parties with non-extremum values before the final comparison round. This preliminary filtering reduces the number of active participants in subsequent rounds, thereby reducing communication overhead while ensuring that the security-critical comparison rounds involve fewer parties.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If homomorphic encryption technology is used for value comparison, then data privacy is protected, but computation complexity increases

Engineering Contradiction:
Improvedata privacyVSAvoidcomputation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by using homomorphic encryption only for the critical comparison operations where privacy is most needed, rather than encrypting all data throughout the entire computation process. In non-critical phases such as data filtering and mean calculation, the system uses plaintext or less computationally intensive encryption methods, thereby reducing overall computation complexity while maintaining privacy where essential.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the encryption parameter state by switching between different encryption modes based on the computation phase. During rounds requiring high privacy protection, full homomorphic encryption is applied; during intermediate rounds, the system transitions to lighter cryptographic primitives or plaintext processing, dynamically adjusting the security-computation tradeoff based on the specific requirements of each computation stage.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If multiple communication rounds are executed in multi-party scenarios, then comparison accuracy is improved, but communication overhead increases

Engineering Contradiction:
Improvecomparison accuracyVSAvoidcommunication overhead
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent implements partial action by not requiring all n parties to participate in every comparison round. Instead, in each round, only a selected subset of parties (those likely to have extremum values based on previous rounds' results) actively participate in the comparison. This partial participation maintains comparison accuracy for the extremum detection while significantly reducing the communication overhead from O(n²) to O(n) per round.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent uses preliminary filtering in earlier rounds to identify and focus subsequent comparison rounds on a smaller subset of candidate parties. This preliminary action reduces the search space for the extremum, allowing the system to achieve the same comparison accuracy with fewer full-round communications, thereby reducing total communication overhead across all rounds.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS12506603B2Method, device, and storage medium for determining extremum based on secure multi-party computation
Publication Date: 2025.12.23 TENCENT TECHNOLOGY (SHENZHEN) CO LTD
  • US12506603B2 patent drawing
  • US12506603B2 patent drawing
  • US12506603B2 patent drawing

AI summary

Method for determining an extremum based on secure multi-party computation includes: acquiring a tth mean obtained in tth round federated computation; performing (t+1)th round federated computation based on valid node data of an ith node device in response to the valid node data of the ith node device being greater than the tth mean; performing the (t+1)th round federated computation based on invalid node data in response to the valid node data of the ith node device being less than or equal to the tth mean; and determining that the valid node data of the ith node device is the extremum in response to the valid node data of the ith node device being greater than or equal to an (n−1)th mean after (n−1)th round federated computation.