Identity-Based Key Exchange Using Split Token and PIN

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Solution Overview

Problem

Existing two-factor authentication systems rely on expensive smart-card tokens or password-only schemes, which are insecure and vulnerable to Key Compromise Impersonation (KCI) attacks and identity spoofing, especially when using insecure storage for tokens.

Innovation Solution

A system and method utilizing a Trusted Authority to issue identity-based secret numbers that are split into a PIN and a larger Token, allowing for secure two-factor authentication through elliptic curve bilinear pairing, where the Token can be stored insecurely and the PIN is used to derive a session key, preventing eavesdroppers from determining the PIN and mitigating KCI attacks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If smart-card tokens are used for two-factor authentication, then security is improved, but device cost and complexity increase

Engineering Contradiction:

Improveauthentication securityVSAvoidtoken complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the authentication system into three distinct components: (1) an insecurely stored token that can be any arbitrary value, (2) a securely stored PIN known only to the user, and (3) a server-side secret. This segmentation eliminates the need for complex smart-card tokens while maintaining security through the combination of these simpler elements.

Inventive Principle:

Principle #1Segmentation

2Device complexity

If password-only schemes are used, then device complexity is reduced, but security against KCI attacks and identity spoofing worsens

Engineering Contradiction:

Improveauthentication system complexityVSAvoidresistance to KCI attacks

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent introduces an intermediary element - the server-stored secret - that mediates between the client's PIN and the authentication service. This intermediary prevents Key Compromise Impersonation attacks because even if an attacker obtains the client's PIN, they cannot authenticate as the client without also knowing the server's secret, which is protected by the server's own PIN.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If tokens are stored insecurely, then ease of storage is improved, but security against token theft worsens

Engineering Contradiction:

Improvetoken storage convenienceVSAvoidtoken security

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent converts the potential harm of insecure token storage into a benefit by designing the system so that the token's insecurity is actually advantageous. The token can be stored in plain text in browser storage or transmitted over unsecured channels, which simplifies implementation and eliminates the need for secure storage mechanisms. The real security comes from the combination of the token with the secret PIN and server secret, not from the token itself.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS9154302B2System and method for secure two-factor authenticated ID-based key exchange and remote login using an insecure token and simple second-factor such as a PIN number

Publication Date: 2015.10.06 MIRACL DIGITAL SERVICES LTD

AI summary

A system and method of authenticated ID-based key exchange and remote login with insecure token and PIN number can provide an authenticated key agreement protocol based on an elliptic curve bilinear type-3 pairing. A server acts as an Authentication Service to Clients and a Trusted Authority (TA) issues identity based secret numbers to Clients and Authentication Services. Included in the system and method is the capability for the Client to split their secret number into two parts, a Client selected PIN number, and the larger number, the Token.