Ciphertext Matching System for Biometric Authentication
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Solution Overview
Problem
Existing biometric authentication systems face issues with heavy server load, data plaintext exposure, and calculation costs that depend on the allowable ambiguity parameter, leading to inefficient processing and potential security vulnerabilities.
Innovation Solution
A ciphertext matching system that generates a first-distance-related ciphertext keeping the distance between registered and matching target data secret using random numbers, with a public key and secret key system to determine match eligibility without revealing the actual distance, thereby reducing dependency on the ambiguity parameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional biometric authentication systems use plaintext data processing, then authentication accuracy is improved, but server load increases and data security deteriorates
Solution Approach 1:
The patent introduces a ciphertext matching apparatus as an intermediary that performs distance calculation on encrypted data without decryption. This mediator enables authentication decisions to be made on ciphertexts, eliminating the need to expose plaintext biometric data to the server while maintaining matching accuracy through homomorphic operations.
Solution Approach 2:
The patent replaces the mechanical plaintext processing system with a cryptographic system using homomorphic encryption. Instead of computing distances on plaintext and comparing results, the system computes encrypted representations of distances and compares ciphertexts, substituting traditional mechanical comparison with cryptographic operations that preserve security.
2Reliability
If the system uses homomorphic encryption for biometric authentication, then data security is improved, but calculation complexity increases
Solution Approach 1:
The patent changes the parameter of data representation from plaintext to ciphertext, enabling all subsequent operations to be performed in the encrypted domain. This parameter change allows the system to maintain security while using standard mathematical operations (addition, multiplication) that are computationally efficient, avoiding the need for complex cryptographic protocols.
Solution Approach 2:
The patent segments the authentication process into distinct modular components: encryption module, distance calculation module, and comparison module. Each component operates independently on encrypted data, allowing optimization of individual functions and reducing overall system complexity through divide-and-conquer architecture.
3Loss of information
If the system stores encrypted biometric templates, then information leakage is prevented, but matching processing time increases
Solution Approach 1:
The patent performs preliminary encryption of biometric templates before storage, and pre-computes encrypted distance metrics during registration. This preliminary action allows rapid matching during authentication by simply comparing pre-prepared ciphertexts rather than performing complex calculations in real-time, reducing authentication time while maintaining security.
Solution Approach 2:
The patent creates encrypted copies of biometric data and distance metrics that can be stored and compared without accessing the original plaintext. These ciphertext copies enable rapid matching operations while the actual biometric information remains protected, achieving both speed and security through cryptographic copying.
4Measurement precision
If the system uses traditional distance calculation methods, then matching accuracy is improved, but dependency on ambiguity parameter increases
Solution Approach 1:
The patent introduces encrypted distance calculations as an intermediary that eliminates direct dependency on ambiguity parameters. By computing and comparing encrypted distance values, the system can determine matches without requiring explicit threshold parameter adjustments, making the matching process more adaptable to different scenarios without manual parameter tuning.
Data Source
AI summary
A ciphertext matching system, includes: a registration target data generation apparatus, a matching request apparatus, a data matching apparatus, and a matching support apparatus. The data matching apparatus generates a first-distance-related ciphertext in which a first distance between registered data and matching target data is kept secret by random numbers. The matching support apparatus generates a public key and a secret key and transmits the generated public key to the individual apparatuses. The data matching apparatus transmits the first-distance-related ciphertext to the matching support apparatus. The matching support apparatus determines whether the first distance obtained by decrypting the first-distance-related ciphertext with the secret key is included in a set of second distances in which the registered data and the matching target data are allowable to be matched each other and transmits a result of the determination to the data matching apparatus.