Decryption Device Using Dual Basis Pairing for Adaptive Security

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Solution Overview

Problem

The security of existing predicate encryption schemes, particularly those using arithmetic branching programs, is not adaptive and lacks practical security enhancements.

Innovation Solution

A decryption device that performs pairing operations on ciphertexts with predicate vectors and attribute vectors set over dual bases, enhancing security while allowing a wide range of predicates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a predicate encryption scheme using arithmetic branching programs is implemented, then a wide range of predicates can be supported, but the security is not adaptive and lacks practical security enhancement

Engineering Contradiction:

Improverange of supported predicatesVSAvoidadaptive security

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The attribute vector and predicate vector are segmented into different basis representations (basis B for attributes, basis B* for predicates). This segmentation allows independent optimization of each vector type while maintaining their relationship through the pairing operation, enabling both wide predicate support and adaptive security

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces asymmetric basis representations where attribute vectors use basis B and predicate vectors use basis B*. This asymmetric structure creates a more secure framework that supports adaptive security while maintaining the ability to evaluate a wide range of predicates through the pairing operation

Inventive Principle:

Principle #4Asymmetry

2Reliability

If dual bases in dual vector spaces are used for ciphertext and decryption key, then security is enhanced, but device complexity increases

Engineering Contradiction:

ImprovesecurityVSAvoidcomplexity of dual basis structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The dual bases B and B* serve multiple functions simultaneously: they provide the mathematical foundation for adaptive security, enable efficient pairing operations, and support the representation of both attribute and predicate vectors. This multi-functionality reduces the need for separate security mechanisms, offsetting the complexity with operational efficiency

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent replaces traditional cryptographic security mechanisms with a mathematical structure based on dual bases and pairing operations. This substitution creates a more elegant and potentially more secure system, where the security properties emerge naturally from the mathematical structure rather than from complex protocol designs

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11909873B2Decryption device, cryptographic system, and decryption method

Publication Date: 2024.02.20 MITSUBISHI ELECTRIC CORP

AI summary

An encryption device (20) generates a ciphertext by setting, in the ciphertext, one of a predicate vector of arithmetic branching programs (ABP) and an attribute vector over a basis B of the basis B and a basis B*, which are dual bases in dual vector spaces. A key generation device (30) generates a decryption key by setting, in the decryption key, the other one of the predicate vector and the attribute vector over the basis B*. A decryption device (40) decrypts the ciphertext by performing a pairing operation on the ciphertext generated by the encryption device (20) and the decryption key generated by the key generation device (30).