Homomorphic Re-Encryption for Secure Cloud Data Aggregation

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Solution Overview

Problem

Current data aggregation methods in cloud computing face challenges in ensuring privacy preservation and secure access to aggregated data, particularly when the requesting party is unpredictable, as existing homomorphic encryption solutions struggle to distribute processed results to eligible requestors while protecting the privacy of data providers.

Innovation Solution

The implementation of a homomorphic re-encryption method using Paillier cryptosystem, where data providers encrypt their data with the requestor's public key, allowing a third authorized party to re-encrypt the results using their secret key, ensuring only the eligible requestor can decrypt the results, thus controlling access and preserving privacy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If homomorphic encryption is used to preserve privacy of data providers, then privacy protection is improved, but the complexity of distributing processed results to eligible requestors increases

Engineering Contradiction:
Improveprivacy protectionVSAvoidcomplexity of distributing processed results
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces a cloud service provider as an intermediary that holds the secret key and performs re-encryption operations. This intermediary enables the third authorized party to securely distribute processed results to eligible requestors without exposing the underlying secret key, thus resolving the complexity of key management and result distribution while maintaining privacy protection through homomorphic encryption properties

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If fully homomorphic encryption schemes are used to enable secure data aggregation, then privacy preservation is improved, but computation complexity increases

Engineering Contradiction:
Improveprivacy preservationVSAvoidcomputation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the encryption and decryption operations into distinct phases: data providers perform homomorphic encryption locally, the cloud service provider performs re-encryption operations on aggregated results, and the third authorized party performs final decryption. This segmentation avoids the need for fully homomorphic encryption throughout the entire process, reducing overall computation complexity while maintaining security

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cloud service provider acts as an intermediary that performs re-encryption operations, eliminating the need for the third authorized party to directly handle complex homomorphic decryption. This intermediary approach simplifies the computational burden by distributing cryptographic operations across multiple trusted parties rather than requiring a single entity to perform all computationally intensive operations

Inventive Principle:
Principle #24Intermediary (Mediator)

3Loss of information

If data is collected from multiple entities for aggregation, then the value of aggregated information is improved, but the risk of privacy leakage increases

Engineering Contradiction:
Improvevalue of aggregated informationVSAvoidrisk of privacy leakage
Core Design Contradiction:
Loss of informationVSObject-affected harmful factors

Solution Approach 1:

Data providers perform homomorphic encryption on their data before submitting it to the cloud service provider. This preliminary encryption action ensures that data remains protected throughout the aggregation process, allowing the system to collect and process information from multiple entities while preventing privacy leakage from the outset rather than attempting to protect it after collection

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3387809B1Schemes of homomorphic re-encryption
Publication Date: 2021.04.21 NOKIA TECHNOLOGIES OY
  • EP3387809B1 patent drawingFigure 1
  • EP3387809B1 patent drawingFigure 2
  • EP3387809B1 patent drawingFigure 3

AI summary

Method and apparatus are disclosed for homomorphic re-encryption schemes in a system comprising a cloud service provider (CSP), a third authorized party (TAP), a data requestor (DR) and a plurality of data providers (DPs). According to an embodiment, a method implemented at a CSP comprises: in response to a request from a TAP, obtaining from a plurality of DPs cipher texts of their respective data, based on the request, wherein each DP is able to homomorphically encrypt its data; analyzing the cipher texts; and sending the analyzing result to the TAP, wherein the TAP is able to re-encrypt the analyzing result, such that a DR can decrypt the re-encrypted analyzing result with the DR's secret key. According to another embodiment, a method implemented at a CSP comprises: collecting from a plurality of DPs cipher texts of their respective data, wherein each DP is able to homomorphically encrypt its data; analyzing the cipher texts; in response to a request from a TAP, encrypting the analyzing result; and sending the encrypted analyzing result to the TAP, wherein the TAP is able to re-encrypt the encrypted analyzing result, such that a DR can decrypt the re-encrypted analyzing result with the DR's secret key.