Secure Enclave Memory Partitioning via Bypass Controller

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Solution Overview

Problem

Mobile devices face vulnerabilities in securing values and parameters stored in secure memory partitions due to integration with unsecure memory partitions, which can lead to unauthorized access and corruption from malicious attacks or inadvertent events.

Innovation Solution

Implementing a secure enclave computing device that bypasses the untrusted memory controller to write and confirm values and parameters directly to a secure memory partition, ensuring integrity by monitoring the interface between the memory controller and memory devices and using hardwired circuitry to control access and prevent unauthorized operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If secure memory partition is integrated with unsecure memory partition, then device complexity is reduced and manufacturing is easier, but security and integrity of stored values are compromised due to unauthorized access and corruption risks

Engineering Contradiction:
Improveintegration easeVSAvoidsecurity integrity
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent divides the memory system into distinct secure and unsecure partitions within the same memory device. The secure partition is accessed through a dedicated secure interface that is physically separated from the unsecure interface, allowing both partitions to coexist in the same physical memory array while maintaining logical and access separation. This segmentation enables easy manufacturing (single device) while preserving security integrity (separated access paths).

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a secure interface as an intermediary between the processor and the secure memory partition. This secure interface acts as a mediator that validates and controls all access to the secure partition, preventing direct access from unsecure code or processes. The intermediary ensures that only authenticated and authorized operations can access the secure data, maintaining security while allowing integration with unsecure memory in the same device.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If untrusted memory controller is used to access secure memory partition, then device complexity is reduced, but vulnerability to malicious attacks and inadvertent events increases

Engineering Contradiction:
Improvecontroller architectureVSAvoidattack vulnerability
Core Design Contradiction:
Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent segments the memory controller functionality into two distinct paths: a secure interface and an unsecure interface. The secure interface is dedicated exclusively to accessing the secure memory partition, while the unsecure interface accesses the unsecure partition. This segmentation ensures that even if the unsecure controller is compromised, the secure partition remains protected through its dedicated, isolated access path, reducing attack vulnerability while maintaining relatively simple device architecture.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies different security qualities to different access paths within the same memory device. The secure interface implements stringent security measures including authentication, encryption, and access validation specifically for the secure partition, while the unsecure interface uses standard access mechanisms. This local differentiation of security quality allows the system to maintain low overall complexity while providing high security where needed.

Inventive Principle:
Principle #3Local quality

3Ease of operation

If secure enclave computing device writes values through memory controller to secure memory, then ease of operation is improved, but risk of unauthorized access and corruption from untrusted controller increases

Engineering Contradiction:
Improvewrite operation simplicityVSAvoiddata protection
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent introduces a secure interface as an intermediary that sits between the secure enclave computing device and the memory controller. This secure interface intercepts and validates all write operations destined for the secure partition, ensuring that only authenticated and authorized data can be written. The intermediary maintains ease of operation for legitimate writes while providing an additional layer of protection against unauthorized access and corruption from the untrusted memory controller.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements preliminary security checks and validations at the secure interface before data is written to the secure memory partition. The secure interface verifies authentication credentials, validates data integrity, and checks access permissions before allowing any write operation to proceed. This preliminary anti-action prevents potential corruption or unauthorized access before it can occur, maintaining both ease of operation for legitimate writes and strong data protection.

Inventive Principle:
Principle #9Preliminary anti-action

Data Source

PatentEP3933649B1Method, system and circuit for managing a secure memory partition
Publication Date: 2023.11.29 ARM LTD
  • EP3933649B1 patent drawingFigure 1
  • EP3933649B1 patent drawingFigure 2
  • EP3933649B1 patent drawingFigure 3

AI summary

Disclosed are methods, systems and devices for storing states in a memory in support of applications residing in a trusted execution environment (TEE). In an implementation, one or more memory devices accessible by a memory controller may be shared between and/or among processes in an untrusted execution environment (UEE) and a TEE.