Networked Firmware Integrity Verification via Intermediary Hashing

Solution Overview

Problem

Existing methods for ensuring the integrity and authenticity of firmware or software are vulnerable to manipulation, as a manipulated device can still respond with a valid checksum, making it difficult to detect integrity breaches during updates.

Innovation Solution

A method and system that utilize a hash function to check the integrity of data stored in a first device by a second device over a network, where the first device calculates a hash value based on stored data and a parameter, and the second device verifies this hash value to ensure data integrity, preventing manipulation by ensuring only the device with complete data can generate the correct hash value.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a checksum is stored in the manipulated unit to respond to inquiries, then the unit can feign integrity of stored software, but the stored checksum no longer corresponds to the actual checksum of the software currently present

Engineering Contradiction:

Improveintegrity checking capabilityVSAvoidmanipulation vulnerability

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary action by having the second device calculate and store the expected hash value in advance, before the firmware update process. This pre-calculated hash value is then used to verify the integrity of the updated firmware, preventing attackers from using pre-stored checksums to feign integrity. The verification happens after the update but uses information prepared beforehand.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces a second device as an intermediary that performs the hash calculation and verification. This mediator device independently calculates the hash value based on the firmware data and compares it with the stored hash value, rather than relying on checksums provided by the first device itself. This intermediary verification mechanism prevents the first device from manipulating its own integrity proof.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If digital signatures are used to check integrity during firmware update, then security against manipulation is improved, but the memory chip cannot be simply replaced and checks must be performed during installation

Engineering Contradiction:

Improvefirmware authenticityVSAvoidfirmware update flexibility

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent applies preliminary action by having the second device calculate and store the expected hash value in advance, before the firmware update process. This pre-calculated hash value is then used to verify the integrity of the updated firmware, preventing attackers from using pre-stored checksums to feign integrity. The verification happens after the update but uses information prepared beforehand.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the verification parameter from a static checksum stored in the device to a dynamic hash value calculated by an intermediary device. The hash function and its parameters (such as the firmware version identifier) can change with each update, making it impossible to use old verification values for new firmware versions. This ensures that each firmware update requires fresh verification.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If hardware measures such as sealing are used to protect against manipulation, then no further manipulation is possible, but firmware updates are also blocked

Engineering Contradiction:

Improvemanipulation protectionVSAvoidfirmware update capability

Core Design Contradiction:

Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The patent introduces a second device as an intermediary that performs the hash calculation and verification. This mediator device independently calculates the hash value based on the firmware data and compares it with the stored hash value, rather than relying on checksums provided by the first device itself. This intermediary verification mechanism prevents the first device from manipulating its own integrity proof.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the verification parameter from a static checksum stored in the device to a dynamic hash value calculated by an intermediary device. The hash function and its parameters (such as the firmware version identifier) can change with each update, making it impossible to use old verification values for new firmware versions. This ensures that each firmware update requires fresh verification.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS8683219B2Method and apparatus for checking the integrity of data stored in a predetermined memory area of a memory

Publication Date: 2014.03.25 SIEMENS AG

AI summary

A method checks the integrity of data stored in a predetermined memory area of a memory of a first device. The first device is coupled to at least one second device by a network The method involves providing at least one parameter which is suitable for influencing a hash value of at least one predetermined hash function. At least one hash value is calculated on the basis of the data stored in the predetermined memory, the at least one predetermined hash function and the at least one parameter. The second device checks the integrity of the data stored in the predetermined memory area of the first device on the basis of the calculated hash value or values.