Multivariate Polynomial Authentication Device for Active Attack Security

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Solution Overview

Problem

Existing public key authentication schemes fail to guarantee a sufficient security level for active attacks, especially in parallel-repetition configurations, as they lack collision resistance and cannot prevent the verifier from determining which secret key was used during the interactive protocol.

Innovation Solution

An authentication device and method that utilizes a key holding unit for multiple secret and public keys based on multivariate polynomials, enabling an interactive protocol to prove knowledge of secret keys without revealing which key was used, ensuring security even in parallel-repetition configurations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing public key authentication schemes are used in parallel-repetition configurations, then authentication can be performed efficiently, but the security level for active attacks is not guaranteed because the verifier can determine which secret key was used

Engineering Contradiction:

Improvesecurity level for active attacksVSAvoidverifier determines which secret key was used

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The authentication scheme is divided into multiple independent authentication instances, each using a different secret key. The prover selects a subset of these instances to respond to, preventing the verifier from determining which specific secret key was used for authentication, thus maintaining security in parallel-repetition configurations

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A commitment mechanism serves as an intermediary between the prover and verifier. The prover commits to a set of authentication instances before the verifier issues challenges, ensuring that the verifier cannot determine which secret key was used while maintaining the integrity of the authentication process

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If multiple secret keys are held and used in interactive protocol, then security against active attacks is improved, but the device complexity increases due to managing multiple key pairs

Engineering Contradiction:

Improvesecurity against active attacksVSAvoidmanaging multiple key pairs

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Multiple authentication instances are merged into a single authentication protocol execution. The prover manages multiple secret keys but only needs to perform authentication operations on a selected subset, reducing the operational complexity while maintaining enhanced security through the use of multiple keys

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The authentication protocol dynamically selects which secret keys to use based on the specific authentication instance and verifier challenge. This dynamic key selection allows the system to adaptively manage multiple keys without requiring complex static key management structures

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS9076000B2Authentication device, authentication method, and program

Publication Date: 2015.07.07 SONY GROUP CORP

AI summary

An authentication device includes circuitry that holds L (L≧2) secret keys si (i=1 to L) and L public keys yi that satisfy yi=F(si) with respect to a set F of multivariate polynomials of n-th order (n≧2). The circuitry also performs with a verifier, an interactive protocol for proving knowledge of (L−1) secret keys si that satisfy yi=F(si). The circuitry receives L challenges from the verifier, arbitrarily selects (L−1) challenges from the L challenges received. The circuitry also generates, by using the secret keys si, (L−1) responses respectively for the (L−1) challenges selected, and transmits the (L−1) responses generated.