Lattice-Based Homomorphic Proxy Re-Encryption for Batch Evaluation
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Solution Overview
Problem
Conventional proxy re-encryption methods are identity-based and incur expensive operations, generate long ciphertexts, and do not support fine-grained operations or batch evaluation, making them impractical for real-life applications.
Innovation Solution
A lattice-based homomorphic proxy re-encryption scheme that utilizes probabilistic key generation, encryption, and re-encryption algorithms to efficiently transform ciphertexts between different public keys, enabling seamless data sharing and decryption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional identity-based proxy re-encryption methods are used, then encryption and re-encryption functionality is provided, but computational complexity increases and operation efficiency decreases
Solution Approach 1:
The patent changes the fundamental parameters of the cryptographic system by adopting lattice-based cryptography instead of conventional identity-based methods. This involves using polynomial rings and modular arithmetic with carefully selected parameters (n, q, t) to achieve both security and efficiency, resolving the contradiction between operational efficiency and computational complexity
Solution Approach 2:
The patent substitutes conventional cryptographic mechanisms with lattice-based mathematical structures. Instead of relying on traditional pairing-based or identity-based cryptographic mechanisms, it uses polynomial multiplication and modular reduction in ring structures, which provides both security and computational efficiency
2Quantity of substance
If conventional encryption schemes are used, then basic encryption functionality is provided, but ciphertext length increases and storage efficiency decreases
Solution Approach 1:
The patent optimizes ciphertext length by carefully selecting lattice parameters (n, q, t) and using compact polynomial representations. The encryption scheme produces ciphertexts that are significantly shorter than conventional schemes while maintaining security, improving both storage efficiency and transmission overhead
3Adaptability or versatility
If conventional proxy re-encryption methods are used, then basic re-encryption functionality is provided, but fine-grained operations on ciphertext are not supported
Solution Approach 1:
The patent creates a universal proxy re-encryption system that can perform multiple functions: standard re-encryption, fine-grained controlled re-encryption, and homomorphic operations on ciphertexts. The lattice-based structure naturally supports these diverse operations without requiring separate cryptographic primitives, achieving versatility while maintaining manageable system complexity
4Productivity
If conventional encryption schemes are used, then basic security is provided, but batch evaluation of ciphertexts is not supported
Solution Approach 1:
The patent merges multiple cryptographic functionalities into a unified lattice-based framework. By combining proxy re-encryption with homomorphic evaluation capabilities in a single system, it enables batch processing of multiple ciphertexts simultaneously, improving productivity while the underlying lattice structure keeps algorithmic complexity manageable through efficient polynomial operations
Data Source
AI summary
The present disclosure a method for a lattice-based homomorphic proxy re-encryption scheme. Conventional methods are attribute based and the attribute-based encryption schemes employ very expensive operations and generate long ciphertexts and secret keys (whose sizes also increase linearly with the size of the access policy), which makes them hard to implement in real-life applications. The present disclosure provides a unidirectional, single-hop HPRE scheme from the Learning With Errors (LWE) assumption which is Chosen Plaintext Attack (CPA) secure. Further, the present disclosure is based on the widely accepted BGV algorithm that supports both levelled FHE operations as well as arbitrary number of ciphertexts with unique and secure re-encryption key generation. Further, the present disclosure provides batch evaluation of ciphertexts, in order to enable re-encryption and evaluation of multiple ciphertexts.