Printer Component Authentication via Challenge-Response Segmentation

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Solution Overview

Problem

Existing authentication methods for determining genuine printer components, such as consumable parts and optional devices, are vulnerable to key exposure and copying due to reliance on shared key encryption, which can lead to malfunction and security breaches.

Innovation Solution

A method where the authentication-target apparatus sends identification information of its key table to the authentication apparatus, which then sends a challenge corresponding to the key table and authentication table IDs, allowing the authentication-target apparatus to generate a response using the stored key, and the authentication apparatus authenticates based on pre-generated challenge-response pairs stored in its authentication table.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If shared key encryption is used for authentication, then authentication can be performed between the apparatus and attachment, but the shared key can be stolen by attackers through analysis of the authentication apparatus or attachment

Engineering Contradiction:

Improveauthentication securityVSAvoidkey exposure risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent divides the authentication system into two separate entities: an authentication apparatus that stores challenge-response pairs, and an attachment that stores only a secret key. This segmentation ensures that the attachment cannot generate responses without the secret key, while the authentication apparatus cannot generate challenges without the challenge data. Even if one component is compromised, the other remains secure, preventing key exposure attacks.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent pre-generates and stores multiple challenge-response pairs in the authentication apparatus before authentication occurs. The challenge data and corresponding response data are prepared in advance, allowing the system to perform rapid authentication without computing responses in real-time. This preliminary preparation enhances authentication speed while maintaining security through the use of pre-computed secure pairs.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the authentication apparatus and authentication-target apparatus both store the shared key in a tamper-resistant chip, then authentication processing can be performed securely, but if either is analyzed the shared key can be exposed enabling copying of the genuine product

Engineering Contradiction:

Improveauthentication processing securityVSAvoidtamper-resistant storage requirement

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the secret key from the authentication apparatus and places it exclusively in the attachment. The authentication apparatus no longer stores the shared key, eliminating the risk of key exposure from analyzing the authentication apparatus. The attachment becomes the sole custodian of the secret key, and its tamper-resistant properties are sufficient to protect against key extraction attacks.

Inventive Principle:

Principle #2Taking out (Extraction)

3Measurement precision

If challenge-response authentication is implemented, then genuine products can be authenticated, but the system requires both parties to hold the shared key which increases vulnerability to attacks

Engineering Contradiction:

Improvegenuine product identification accuracyVSAvoidattack surface expansion

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent inverts the traditional challenge-response model by having the attachment (authentication target) generate the response using its secret key, rather than having the authentication apparatus generate the response. The authentication apparatus sends a challenge and verifies the response, but does not possess the secret key itself. This inversion reduces the attack surface by eliminating the need for the authentication apparatus to store sensitive key material.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS11296896B2Method of authenticating authentication-target apparatus using challenge and response

Publication Date: 2022.04.05 CANON KK

AI summary

A target sends ID of a key table. The apparatus receives the ID. The apparatus sends ID of an authentication table to the target. The apparatus sends a challenge corresponding to a pair of the ID of the key table and the ID of the authentication table, to the target. The target obtains, from the key table, a key corresponding to a pair of the ID of the key table and the ID of the authentication table. The target generates a response from the challenge and the key. The target sends the response to the apparatus. The apparatus obtains, from the authentication table, a response corresponding to a pair of the ID of the key table and the ID of the authentication table. The apparatus authenticates the target based on the responses.