Cryptographic Watchdog Timer for TPM Malware Reset
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Solution Overview
Problem
Trusted Platform Modules (TPMs) in computing devices can be compromised by malware, leading to erratic behavior and resource wastage, as seen in devices like electricity meters, which existing technologies fail to effectively mitigate.
Innovation Solution
Implementing a cryptographic watchdog timer in the TPM that forces a device reset if it fails to solve a cryptographic challenge within a specified time, using a remote service to provide the necessary cryptographic token, allowing the remote service to control and reset the device if compromised by malware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a TPM is exposed to malware, then the device can perform discrete functions (e.g., collect and transmit data), but the device may operate unconventionally and waste resources due to malware control
Solution Approach 1:
The system implements a feedback mechanism where the TPM periodically proves its integrity by solving cryptographic challenges. The remote service monitors these proofs and can detect malware presence. When malware is detected, the remote service withholds cryptographic tokens, causing the watchdog timer to expire and trigger a reset, thereby feedback-looping the detection and response mechanism.
Solution Approach 2:
The patent introduces a remote service as an intermediary between the TPM and the malware. The remote service receives cryptographic proofs from the TPM, evaluates them for legitimacy, and issues cryptographic tokens accordingly. This intermediary layer enables the system to detect and respond to malware without direct exposure of the TPM to malicious code.
2Reliability
If the TPM continuously proves its integrity, then malware detection is improved, but the device may be reset frequently causing operational disruption
Solution Approach 1:
Instead of continuous monitoring, the system uses periodic cryptographic challenges that the TPM must solve at predetermined intervals. The watchdog timer is reset upon successful challenge resolution. This periodic action reduces the frequency of interruptions while maintaining reliable detection, as the TPM must prove its integrity at each challenge cycle rather than continuously.
Solution Approach 2:
The system performs preliminary cryptographic challenges before actual malware execution can cause harm. By requiring the TPM to solve challenges and prove integrity in advance, the system can detect and reset infected devices before they complete malicious operations, preventing resource wastage while reducing the frequency of operational disruptions.
3Object-affected harmful factors
If the remote service withholds cryptographic tokens, then malware control is enabled, but the device cannot perform its discrete functions
Solution Approach 1:
The patent converts the harmful effect of malware into a beneficial control mechanism. The remote service uses the same cryptographic token issuance process that enables legitimate device operation to also detect and respond to malware. When malware is detected, the service withholds tokens, causing the watchdog timer to expire and trigger a reset—transforming the token withholding mechanism into a dual-purpose tool for both operational control and security enforcement.
Data Source
AI summary
A computing device's trusted platform module (TPM) is configured with a cryptographic watchdog timer which forces a device reset if the TPM fails to solve a cryptographic challenge before the expiration of the timer. The computing device's TPM is configured to generate the cryptographic challenge, to which the computing device does not possess the cryptographic token for resolution. While the watchdog timer counts down, the computing device requests a cryptographic token from a remote service to solve the challenge. The remote service transmits the cryptographic token to the computing device so long as the remote service identifies no reason to withhold the token, such as the computing device being infected with malware. The interoperability of the computing device and remote service enables the remote service to exercise control and reset capabilities over the computing device.