TPM and Trusted Root Device Authentication via Challenge-Response
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Solution Overview
Problem
Computer systems face vulnerabilities due to the inability of Trusted Platform Modules (TPM) to initiate security checks, making them susceptible to attacks where an attacker can replace the Trusted Root Device, thereby compromising system security.
Innovation Solution
A challenge-response transaction is initiated between the TPM and the Trusted Root Device using a secret key shared between them, ensuring that resources are only released if the Trusted Root Device is successfully authenticated, thereby preventing unauthorized access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the TPM is used to store resources without initiation capability, then resource storage is simplified, but security is compromised due to inability to initiate authentication
Solution Approach 1:
The patent inverts the traditional authentication initiation role: instead of the TPM (security module) initiating authentication, the Trusted Root Device initiates authentication to the TPM. This allows the TPM to maintain its simple resource storage function while the Trusted Root Device provides the initiation capability, resolving the contradiction between simplicity and security.
Solution Approach 2:
The CPU acts as an intermediary that receives challenges from the TPM, forwards them to the Trusted Root Device, and processes responses. This mediator enables the authentication flow between TPM and Trusted Root Device without requiring the TPM to have initiation capabilities, maintaining both simplicity and security.
2Ease of operation
If the TPM releases resources without authentication, then system operation is simplified, but unauthorized access becomes possible
Solution Approach 1:
The system performs preliminary authentication through challenge-response transactions before releasing resources. The TPM issues challenges, the Trusted Root Device responds using secret keys, and only upon successful authentication are resources released. This preliminary security check prevents unauthorized access while maintaining operational simplicity.
Solution Approach 2:
The authentication process uses feedback mechanisms where the TPM issues challenges, receives responses from the Trusted Root Device, verifies them, and then decides whether to release resources. This feedback loop ensures that resource release is contingent on successful authentication, preventing unauthorized access.
3Ease of operation
If secret keys are exposed on interfaces for authentication, then authentication process is simplified, but security is compromised
Solution Approach 1:
The CPU serves as an intermediary that handles the authentication process without exposing secret keys. It receives challenges from the TPM, forwards them to the Trusted Root Device, receives responses, and processes them without the secret keys ever being exposed on insecure interfaces. This maintains both authentication functionality and key security.
Solution Approach 2:
The authentication process is segmented into separate functions: the TPM generates challenges, the Trusted Root Device generates responses using secret keys, and the CPU processes the authentication. This segmentation allows secret keys to remain protected within the Trusted Root Device while still enabling authentication through the intermediary CPU.
Data Source
AI summary
A method for initializing a computer system, which includes a Central Processing Unit (CPU), a Trusted Root Device and a Trusted Platform Module (TPM), includes authenticating a boot code of the CPU using the Trusted Root Device, and booting the CPU using the authenticated boot code. A challenge-response transaction, in which the TPM authenticates the Trusted Root Device, is initiated by the CPU following booting of the CPU. Only in response to successful authentication of the Trusted Root Device using the challenge-response transaction, a resource used in operating the computer system is released from the TPM.