OKVS-Based OPRF Repetition Against Random Substitution Attacks

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Solution Overview

Problem

Existing oblivious pseudo-random function (OPRF) protocols based on oblivious key-value store (OKVS) algorithms are vulnerable to random substitution attacks by malicious receivers, and the communication overhead increases significantly during such attacks.

Innovation Solution

Implement a method involving multiple applications of OPRF protocols using OKVS, adjusting bit counts and probability bounds to minimize information leakage and communication, including configuring first and second bit counts based on specific probability bounds to prevent attackers from obtaining additional data while reducing overall communication.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single OPRF protocol is applied, then communication overhead is low, but security against random substitution attacks is insufficient

Engineering Contradiction:
Improvesecurity against random substitution attacksVSAvoidprotocol complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the security verification process into multiple independent OPRF protocol executions. Instead of relying on a single protocol instance, the system executes the OPRF protocol multiple times with different inputs, where each execution provides an additional layer of security verification. This segmentation allows the system to achieve stronger security guarantees while maintaining the modular structure of the original protocol.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements preliminary verification steps before the main data processing operation. By executing OPRF protocols in advance with test inputs and verifying the results, the system establishes security guarantees beforehand. This preliminary action prevents malicious receivers from performing random substitution attacks during the actual data processing phase.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If multiple OPRF protocols are applied to prevent attacks, then security is improved, but communication overhead increases significantly

Engineering Contradiction:
Improvesecurity against random substitution attacksVSAvoidcommunication overhead
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent optimizes the parameters of the OPRF protocol to reduce communication overhead. By carefully selecting the security parameter λ and the number of repetitions r, the system achieves the desired security level while minimizing the amount of data transmitted. The parameter configuration balances security requirements with communication efficiency.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent extracts only the essential verification elements from the OPRF protocol execution. Instead of transmitting all intermediate computation results, the system identifies and transmits only the critical verification data needed to detect random substitution attacks. This extraction approach maintains security while significantly reducing communication overhead.

Inventive Principle:
Principle #2Taking out (Extraction)

3Loss of information

If bit counts are increased to prevent information leakage, then security is improved, but communication overhead increases

Engineering Contradiction:
Improveinformation leakage preventionVSAvoidcommunication overhead
Core Design Contradiction:
Loss of informationVSQuantity of substance

Solution Approach 1:

The patent carefully configures the bit counts of hash data and PRF data based on the security parameter λ. By setting the hash data bit count to λ bits and the PRF data bit count to 2λ bits, the system achieves the required information leakage prevention while optimizing communication efficiency. This parameter configuration ensures that the probability of successful attacks remains negligible.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4708765A1Method for multiple applications of oblivious pseudo-random function protocol between receiver and sender based on oblivious key-value store algorithm, and device using same
Publication Date: 2026.03.11 SAMSUNG SDS CO LTD
  • EP4708765A1 patent drawingFigure 1
  • EP4708765A1 patent drawingFigure 2
  • EP4708765A1 patent drawingFigure 3~4

AI summary

The present disclosure relates to a method for multiple applications of an oblivious pseudo-random function protocol between a receiver and a sender based on an oblivious key-value store algorithm, and a terminal device using the same, and a method for multiple applications of an oblivious pseudo-random function protocol according to an embodiment of the present disclosure may include the steps of: inputting, by the receiver, a first key-value pair between target data and hash data corresponding to the target data to receive first PRF data generated according to a first OPRF protocol based on the OKVS; and inputting, by the receiver, a second key-value pair between the target data and the first PRF data to receive second PRF data generated according to a second OPRF protocol based on the OKVS.