Rewrite Protection for Firmware Verification Integrity

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Solution Overview

Problem

Existing image processing apparatuses struggle to maintain the roots of trust related to firmware verification effectively, particularly in securing the boot process of hard copy devices, which is crucial for obtaining Common Criteria certification.

Innovation Solution

An image processing apparatus that includes a setter for setting security settings, storages for firmware and verification programs, and controllers for controlling rewrite protection of storage areas, ensuring the verification program's integrity and trustworthiness through differential security settings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If rewrite protection is applied to the verification program storage area, then firmware verification integrity is improved, but flexibility for security setting changes deteriorates

Engineering Contradiction:

Improvefirmware verification integrityVSAvoidsecurity setting flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic rewrite protection by making the protection state changeable based on security settings. The verification program storage area can be switched between protected and unprotected states through controller control, allowing the system to adapt between high security mode (protection enabled) and maintenance mode (protection disabled), thus resolving the contradiction between integrity and flexibility

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the security parameter of the verification program storage area dynamically. By modifying the rewrite protection parameter based on security setting values, the system can transition between different security states, enabling both strong protection when needed and flexibility when security settings change, thereby resolving the contradiction

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If security settings are made flexible and changeable, then adaptability is improved, but security stability deteriorates

Engineering Contradiction:

Improvesecurity setting flexibilityVSAvoidsecurity stability

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary action by establishing security settings before firmware verification operations. The controller configures the rewrite protection state in advance based on the security setting value, ensuring that protection is already in place before critical operations occur, thus maintaining stability while allowing flexibility in configuration

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent carefully controls parameter changes by only modifying security settings through authorized procedures. The security setting value acts as a controlled parameter that can be changed but only triggers corresponding protection state changes through the controller, maintaining system stability while enabling necessary adaptability

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250094597A1Image processing apparatus and execution control method of rewrite protection

Publication Date: 2025.03.20 SHARP KK

AI summary

An image processing apparatus includes a setter that sets any one of a first security setting and a second security setting different from the first security setting in the image processing apparatus, one or more storages that store firmware and a verification program verifying whether or not the firmware has been tampered with, and one or more controllers that control execution of rewrite protection for a part of a storage area including the verification program in accordance with the first security setting or the second security setting set in the image processing apparatus.