Policy-Managed PUF Security Component for Tamper-Resistant Access
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Solution Overview
Problem
Existing Physically Unclonable Functions (PUFs) are not client-aware and lack the ability to protect secrets when accessed by unauthorized parties, making them vulnerable to tampering and compromising device security.
Innovation Solution
A security component with a PUF and a management module that manages the PUF according to a policy, using measurements of booted components and hardware states to configure its behavior, enabling it to adapt to the device environment and enforce secure access to responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a PUF is used to generate unique device responses without storing secrets, then security is improved by eliminating stored secrets, but the PUF becomes vulnerable to unauthorized access and tampering
Solution Approach 1:
The patent applies dynamics by making the PUF configuration changeable based on boot measurements. The PUF is reconfigured during device booting based on measurements of other components, allowing the security behavior to adapt dynamically to the device's actual state rather than being static. This enables the system to respond to tampering attempts by changing its security characteristics.
Solution Approach 2:
The system uses feedback from boot measurements to control PUF configuration. Measurements taken during device booting are used to determine how the PUF should be configured, creating a feedback loop where the security component's behavior is determined by the actual state of the device it protects. This ensures the PUF responds appropriately to the device's integrity state.
2Reliability
If the PUF is made adaptive to device environment through policy-based management, then protection against tampering is improved, but device complexity increases due to additional management module
Solution Approach 1:
The patent segments the security functionality into distinct modules: a management module that handles policy enforcement and configuration, and the PUF itself that generates responses. This segmentation allows the complex policy management functions to be separated from the core PUF operation, making the system more manageable and maintainable despite the added complexity.
Solution Approach 2:
The system performs preliminary actions by taking measurements during the boot process before the PUF is fully operational. These measurements are used to pre-determine the PUF configuration based on predefined policies, so that when the PUF becomes active, it is already properly configured for the device's actual state, avoiding the need for complex runtime adjustments.
3Reliability
If multiple sub-functions are included in the PUF to increase response uniqueness, then security is improved, but the risk of unauthorized access to specific sub-function responses increases
Solution Approach 1:
The patent applies local quality by configuring different sub-functions of the PUF differently based on the device's boot measurements and policy requirements. Rather than treating all sub-functions uniformly, the system can enable, disable, or configure specific sub-functions according to the actual device state, ensuring that only appropriate responses are available in given contexts.
Solution Approach 2:
The system changes parameters of the PUF configuration based on boot measurements. By adjusting configuration parameters such as which sub-functions are active and how they are challenged, the system can adapt the PUF's behavior to match the device's actual state, reducing the risk of unauthorized access to inappropriate responses.
Data Source
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AI summary
A security component (102, 202) for a device (200) is disclosed. The security component (102) comprises a Physically Unclonable Function (PUF) (150) having a plurality of sub functions (152), and a management module (110) that is configured to manage the PUF (150) in accordance with a policy. The management module (110) comprises a measurement module (112) configured to receive, from a device boot process, at least one of a measurement of a component on the device or a measurement of a hardware state of the device, and a rule module (114) configured to compare the received measurement to at least one rule that implements the policy, and to enter a policy state on the basis of the comparison. The management module further comprises a control module (116) configured to configure the PUF (150) in accordance with a policy state entered by the rule module. Also disclosed is a method (300) for operating a security component.