Biometric Data Processing With Functional Encryption Access Control

Solution Overview

Problem

Existing biometric identification systems face challenges in ensuring user privacy and preventing unauthorized access to encrypted biometric databases, as custodians can decrypt and perform unauthorized operations on encrypted data.

Innovation Solution

Implement functional encryption using a functional encryption public key for candidate data and a functional decryption private key for a polynomial function parameterized with reference data, stored in a hardware security module, to perform secure comparisons without exposing the original data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If homomorphic encryption is used to encrypt the biometric database, then data confidentiality is improved, but the custodian can still decrypt and perform unauthorized operations on the encrypted data

Engineering Contradiction:

Improvedata confidentialityVSAvoidunauthorized access by custodian

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces functional encryption as an intermediary mechanism between the custodian and the encrypted biometric database. Instead of giving the custodian direct decryption capabilities, the system uses functional encryption keys that are mathematically constrained to perform only specific operations (distance calculations) on the encrypted data. This intermediary layer prevents the custodian from performing unauthorized operations while still enabling necessary processing.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the cryptographic parameters from standard homomorphic encryption to functional encryption with specific constraints. The functional encryption scheme uses polynomial functions of degree 1 or 2 as the mathematical foundation, which fundamentally alters how the encryption works. This parameter change ensures that decryption is only possible through specific polynomial operations, preventing unauthorized access while maintaining data confidentiality.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If the custodian has the ability to decrypt biometric data, then identification/authentication can be performed, but user privacy is compromised

Engineering Contradiction:

Improveidentification capabilityVSAvoiduser privacy

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent introduces functional encryption as an intermediary mechanism between the custodian and the encrypted biometric database. Instead of giving the custodian direct decryption capabilities, the system uses functional encryption keys that are mathematically constrained to perform only specific operations (distance calculations) on the encrypted data. This intermediary layer prevents the custodian from performing unauthorized operations while still enabling necessary processing.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent extracts the decryption capability from the custodian and replaces it with functional decryption private keys that are generated from reference personal data. These extracted keys can only perform specific polynomial operations on encrypted candidate data, separating the ability to authenticate from the ability to access raw biometric information.

Inventive Principle:

Principle #2Taking out (Extraction)

3Productivity

If reference biometric data is stored in an encrypted database, then identification can be performed, but the database requires secure custodianship which creates privacy risks

Engineering Contradiction:

Improveidentification efficiencyVSAvoidprivacy risks from custodianship

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces functional encryption as an intermediary mechanism between the custodian and the encrypted biometric database. Instead of giving the custodian direct decryption capabilities, the system uses functional encryption keys that are mathematically constrained to perform only specific operations (distance calculations) on the encrypted data. This intermediary layer prevents the custodian from performing unauthorized operations while still enabling necessary processing.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements a self-service mechanism where the encrypted reference biometric data itself generates the functional decryption private keys through polynomial operations. The reference data embedded in the functional keys enables the system to perform authentication operations without requiring a human custodian to manually decrypt or manage the database, reducing privacy risks associated with custodianship.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS12587382B2Method and system for processing biometric data

Publication Date: 2026.03.24 IDEMIA PUBLIC SECURITY FRANCE

AI summary

The invention proposes a method for processing personal data, having the steps of (a) Functional encryption of candidate personal data using a functional encryption public key, (b) For at least one reference personal data, functional decryption of the encrypted candidate biometric data using a functional decryption private key for the polynomial function of degree 1 or 2 parameterized with said reference personal data.