Secure Sequence Rotation for Private Position Detection

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Solution Overview

Problem

Existing techniques fail to obtain a numerical share representing the position of an element with a specific value while keeping the position of that element secret in a sequence of elements.

Innovation Solution

A secure computation system and method that rotates elements of a sequence using a random number share without revealing the actual random number, allowing the position of the specific value to be determined without exposing the original sequence or random number.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the position of an element with a specific value is obtained from a sequence, then the numerical share representing the position can be obtained, but the position information becomes exposed and loses secrecy

Engineering Contradiction:
Improveposition determination accuracyVSAvoidposition secrecy
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The patent introduces an intermediary randomized sequence where the original sequence elements are transformed through a random permutation. This intermediary structure allows position queries to be performed on the randomized version, and the results are then mapped back to the original sequence positions, thereby maintaining secrecy of the original positions while enabling accurate position determination.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the parameter representation by working with randomized position indices rather than direct positions. The system transforms the position query problem into finding positions in a randomized sequence, then uses the known random permutation to translate these randomized positions back to original positions, thus preserving secrecy while enabling accurate measurement.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If the original sequence and random number are revealed to determine position, then accurate position information can be obtained, but data privacy and security are compromised

Engineering Contradiction:
Improveposition information accuracyVSAvoiddata privacy loss
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent uses the randomized sequence as an intermediary that enables position determination without exposing the original sequence or random number. The system performs operations on the randomized version and uses the known random permutation to translate results, thereby achieving accurate position information while maintaining data privacy through the intermediary structure.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a copied and randomized version of the original sequence for position determination operations. This copy allows accurate position queries to be performed, and the results are translated back to original positions using the random permutation, thus obtaining accurate position information without revealing the original sensitive data.

Inventive Principle:
Principle #26Copying

3Productivity

If secure computation is performed without randomization, then computational efficiency is maintained, but position secrecy cannot be preserved

Engineering Contradiction:
Improvecomputation efficiencyVSAvoidposition secrecy
Core Design Contradiction:
ProductivityVSLoss of information

Solution Approach 1:

The patent performs preliminary randomization of the sequence before position determination operations. By pre-randomizing the sequence and storing the random permutation, the system enables subsequent efficient secure computations on the randomized data without repeated randomization overhead, thus maintaining computational efficiency while preserving position secrecy through the preliminary randomization action.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent changes the computational parameter space by working with randomized position indices in the computation. This parameter transformation allows efficient secure computation operations to be performed on the randomized data, with results translated back to original positions, thereby maintaining productivity while ensuring position secrecy is preserved throughout the computation process.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4210031B1Secure computation system, secure computation device, secure computation method, and program
Publication Date: 2025.12.24 NT T INC
  • EP4210031B1 patent drawingFigure 1
  • EP4210031B1 patent drawingFigure 2
  • EP4210031B1 patent drawingFigure 3

AI summary

A secure computation apparatus obtains a sequence pof obtained by rotating elements fp-1, ..., f0 of a sequence f by p elements by secure computation using share of random number p and share of the sequence f without obtaining the random number p and the sequence f, obtains the value b'∈{0, ..., p-1} representing the position of the element cfb' whose value is α among the elements cfp-1, ..., cf0 in the sequence pof, and obtains the share of the value b by secure computation using the share of the random number p and the value b'. Here, p is an integer of 2 or more, f is a sequence of p elements fp-1, ..., f0, a value of one element fb among the elements fp-1, ..., f0 is α, a value of an element other than the element fb is other than α, a value representing a position of the element fb is bE{0, ..., p-1}, and p is a random number represented by an integer.