Secure Crypto-Processor Isolating Trusted I/O Devices
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Solution Overview
Problem
Existing security measures for network-accessible devices are ineffective if the operating system is corrupted or compromised, as they do not provide adequate protection against unauthorized access or malicious attacks.
Innovation Solution
A Secure Crypto-Processor is used to enforce authorization policies and provide attestation for sensitive input/output devices, isolating them from the microcontroller and ensuring only authorized interactions by using Secure IO lines and bus master controllers to manage access and verify data integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If operating system security features are used to protect network-accessible devices, then security protection is provided, but the protection becomes ineffective if the operating system is corrupted or compromised
Solution Approach 1:
The system is divided into two distinct parts: a secure element (hardware security module) and a microcontroller. The secure element contains the security-critical functions and isolated I/O interfaces, while the microcontroller handles general processing. This segmentation ensures that even if the microcontroller or operating system is compromised, the secure element remains protected and can continue to provide security functions.
Solution Approach 2:
The secure element acts as an intermediary between the microcontroller and the isolated I/O devices. It mediates all communications through secure I/O interfaces, enforcing access control policies and verifying data integrity. This intermediary position allows the secure element to protect against malicious attacks even when the operating system is compromised.
2Ease of operation
If I/O devices are directly connected to the microcontroller, then ease of operation is improved, but unauthorized access and data tampering risks increase
Solution Approach 1:
The secure element is positioned as an intermediary between the microcontroller and isolated I/O devices. It handles all communication through secure I/O interfaces, enforcing access control policies and verifying data integrity. This allows I/O devices to remain easily connected while protecting against unauthorized access.
Solution Approach 2:
Security-critical I/O interfaces are extracted from the microcontroller and placed within the secure element. This extraction creates a trusted boundary that isolates sensitive I/O communications from potential compromises in the microcontroller or operating system, while maintaining ease of operation through the secure element's managed access.
3Reliability
If a trusted boundary is created using a secure element, then security against unauthorized access is improved, but device complexity increases
Solution Approach 1:
The system architecture is segmented into a secure element and a microcontroller, with clearly defined interfaces and responsibilities. The secure element handles security-critical functions including access control policy enforcement and data integrity verification, while the microcontroller handles general processing. This segmentation provides strong authorization security while keeping each component's complexity manageable.
Solution Approach 2:
The secure element combines multiple security functions including access control enforcement, data integrity verification, and secure I/O interfacing into a single integrated component. This merging of functions creates a compact trusted boundary that improves authorization security without proportionally increasing overall system complexity.
Data Source
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AI summary
Techniques are provided to ensure isolation of trusted input/output devices using a Secure Crypto-Processor. Secure IO lines may be used to drive devices that have a higher integrity requirement and to do attestation of sensor readings. Enhanced authorization policies may be used to enforce policies on interaction with IO devices. A bus master controller may also be provided in a Secure Crypto-Processor. Individual devices on an isolated Secure Crypto-Processor bus may be mapped to Indices so that read and write operations can be associated with Secure-Crypto-Processor-enforced authorization policies. The Secure Crypto-Processor may further provide means of attestation for complex data read from an input/output device that may be signed with the device identity to show strong origination proof of that data.