Imaging Device Clock Tampering Detection Through Interval Comparison

Solution Overview

Problem

Existing electronic systems face challenges in detecting clock tampering, particularly in imaging devices, where non-authentic components manipulate timers to disable or accelerate functions, compromising system integrity and security.

Innovation Solution

A method involving the comparison of time intervals measured by host firmware and security device clocks to detect clock tampering, where a difference greater than a threshold indicates tampering, preventing normal operation of the device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If timer-based mechanisms are used to deploy firmware functions at certain times, then the electronic device can change behavior during its lifecycle, but the timer can become significantly different from the true time due to tampering

Engineering Contradiction:

Improveability to change behavior during lifecycleVSAvoidtimer accuracy

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent records the start time of a timer in non-writable memory before the timer begins counting. This preliminary action preserves the original start time even if the timer is later tampered with, allowing the system to detect discrepancies between the recorded start time and the current timer value.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors the timer by comparing the current timer value against the recorded start time and expected duration. When the timer completes its intended duration, the system checks whether the elapsed time matches expectations. This feedback mechanism detects tampering attempts and triggers appropriate responses such as preventing firmware updates or alerting administrators.

Inventive Principle:

Principle #23Feedback

2Adaptability or versatility

If the timer is rolled backward or slowed down, then previously enabled functions can be disabled, but this tampering goes undetected by traditional timer-based mechanisms

Engineering Contradiction:

Improvefunction deployment controlVSAvoidtampering detection

Core Design Contradiction:

Adaptability or versatilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent records the start time of a timer in non-writable memory before the timer begins counting. This preliminary action preserves the original start time even if the timer is later tampered with, allowing the system to detect discrepancies between the recorded start time and the current timer value.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors the timer by comparing the current timer value against the recorded start time and expected duration. When the timer completes its intended duration, the system checks whether the elapsed time matches expectations. This feedback mechanism detects tampering attempts and triggers appropriate responses such as preventing firmware updates or alerting administrators.

Inventive Principle:

Principle #23Feedback

3Productivity

If the timer is sped up, then future function deployment can be accelerated, but this manipulation compromises system security

Engineering Contradiction:

Improvefunction deployment speedVSAvoidsystem security

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent records the start time of a timer in non-writable memory before the timer begins counting. This preliminary action preserves the original start time even if the timer is later tampered with, allowing the system to detect discrepancies between the recorded start time and the current timer value.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors the timer by comparing the current timer value against the recorded start time and expected duration. When the timer completes its intended duration, the system checks whether the elapsed time matches expectations. This feedback mechanism detects tampering attempts and triggers appropriate responses such as preventing firmware updates or alerting administrators.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS20250278477A1Methods and systems for detection of clock tampering on an electronic device

Publication Date: 2025.09.04 LEXMARK INTERNATIONAL INC

AI summary

A method of detecting clock tampering in an imaging device, comprising: reading a host start time from a host firmware clock of the imaging device, reading a security start time from a security device clock, and reading a host end time from the host firmware clock, reading a security end time, comparing a host interval time between the host start time and the host end time with a security interval time between the security start time and the security end time, and when a difference between the host interval time and the security interval time exceeds a threshold, determining that the host firmware clock has been tampered with. There is further provided an imaging device that similarly determines if the host firmware clock has been tampered with. Finally, there is provided a security device for an imaging device for determining whether the host firmware clock has been tampered with.