Zone-Based Memory Protection for Secure Computing Units
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Solution Overview
Problem
Current computing systems for embedded and control units, particularly in vehicles, face challenges in ensuring security without compromising operational flexibility, especially in managing access rights and resources across multiple zones.
Innovation Solution
A method is introduced that assigns application programs to specific zones within a computing unit, utilizing memory protection units to control read, write, and execution rights, allowing for secure operation by separating resources and enforcing trust boundaries between zones, and using a lightweight operating system or supervisor to manage computing time and resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If application programs are assigned to specific zones with restricted access rights, then security is improved, but operational flexibility deteriorates
Solution Approach 1:
The memory space is divided into multiple zones (first zone and second zone) with different security levels. Application programs are assigned to specific zones based on their security requirements. The memory protection unit enforces zone boundaries, allowing programs in the first zone to access only first zone memory, while programs in the second zone can access both first and second zone memory. This segmentation resolves the contradiction by providing both security isolation and controlled flexibility through hierarchical access rights.
Solution Approach 2:
Different memory zones are assigned different access rights and security characteristics. The first zone has restricted access (read-only for zone 1 programs), while the second zone has broader access (read-write for zone 2 programs). This local differentiation of quality allows each zone to have optimized security and operational characteristics, resolving the contradiction between security and flexibility at different levels of the system.
2Reliability
If memory protection units are used to control access rights, then security is improved, but device complexity increases
Solution Approach 1:
The memory protection unit is designed as a universal component that handles access control for multiple zones and application programs simultaneously. It implements a general mechanism for enforcing zone boundaries and managing read/write/execute rights that works across different security levels. This multi-functionality reduces the need for separate protection mechanisms for each zone, thereby limiting the increase in device complexity while maintaining strong security.
3Adaptability or versatility
If processor cores are assigned to multiple zones, then operational flexibility is improved, but security management becomes more complex
Solution Approach 1:
The memory protection unit acts as an intermediary between processor cores and memory zones. When a processor core needs to access memory, the memory protection unit mediates the access request by checking the core's assigned zones and the target memory's zone, enforcing appropriate access rights. This intermediary mechanism simplifies security management by centralizing the complex logic of multi-zone access control in a dedicated component, rather than distributing complexity across multiple processor cores.
Data Source
AI summary
A method for operating a computing unit including at least one processor core. The method includes: assigning one or multiple application programs executable by the computing unit to one of at least two zones, the zones characterizing resources of the computing unit, which are usable for an execution of a relevant application program, executing at least one of the application programs as a function of the zone to which it is assigned.