Software Trusted Execution Environment for Mobile App Security

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Solution Overview

Problem

Mobile devices without hardware-based trusted execution environments (TEEs) are vulnerable to malware and attacks, compromising user and service provider security, as they lack the necessary secure computing functionality.

Innovation Solution

A software-based trusted execution environment (Soft TEE) is introduced, allowing mobile applications to be developed with secure components that can execute on devices without hardware TEEs, using cryptographic keys and a Soft TEE virtual machine to isolate and protect sensitive data, and employing white-box cryptography for secure provisioning and runtime memory encryption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If hardware-based trusted execution environments are implemented in mobile devices, then security of mobile applications and sensitive data is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:
ImprovesecurityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent creates a software-based copy of the trusted execution environment functionality that runs on the main processor instead of requiring dedicated hardware. The soft TEE virtual machine replicates the security isolation and cryptographic key management functions of hardware TEEs through software emulation, allowing devices without hardware TEEs to achieve comparable security levels

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent replaces the mechanical/hardware-based trusted execution environment with a software-based system. Instead of relying on physical isolation mechanisms in hardware, the invention uses virtual machine technology, cryptographic protocols, and software enforcement to achieve the same security objectives, thereby eliminating the need for specialized hardware components

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If software-based trusted execution environment is used on devices without hardware TEEs, then security functionality is provided to more devices, but security strength compared to hardware TEEs deteriorates

Engineering Contradiction:
ImprovecompatibilityVSAvoidsecurity strength
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent performs preliminary security actions by establishing cryptographic key pairs and provisioning security credentials before the mobile application is installed and executed. The soft TEE virtual machine is pre-configured with security policies and cryptographic infrastructure, ensuring that security measures are in place before any sensitive operations occur

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent segments the mobile application into trusted and untrusted components, with the soft TEE virtual machine providing isolated execution environments for sensitive operations. This segmentation separates security-critical functions from the general-purpose operating system, ensuring that even if the main system is compromised, the protected functions remain secure

Inventive Principle:
Principle #1Segmentation

3Ease of manufacture

If cryptographic keys are stored in soft TEE virtual machine on devices without hardware security, then security provisioning is simplified, but vulnerability to attacks increases

Engineering Contradiction:
Improveprovisioning simplicityVSAvoidvulnerability to attacks
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a trusted service manager as an intermediary that securely provisions cryptographic keys and security credentials to the soft TEE virtual machine. This intermediary uses secure communication channels and authenticated protocols to transfer sensitive security materials, reducing the risk of key exposure during the provisioning process

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the operational parameters of the cryptographic system by using dynamic key derivation and multiple layers of encryption. Instead of storing keys in a single static location, the system derives keys from master secrets using cryptographic hash functions and stores them in encrypted form, changing the security model from static to dynamic protection

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3387813B1Mobile device having trusted execution environment
Publication Date: 2022.04.20 THALES DIS FRANCE SA
  • EP3387813B1 patent drawingFigure 1
  • EP3387813B1 patent drawingFigure 2
  • EP3387813B1 patent drawingFigure 3

AI summary

A mechanism for securing a mobile app for execution on a mobile device. The mechanism includes loading a non-trusted portion of the mobile app from a non-trusted application provider onto the mobile device, operating a key provisioning server to generate keys associated with a trusted execution environment, transmitting the keys associated with the trusted execution environment to the mobile device and to a key directory server, authenticate the mobile device, and upon authenticating the mobile device, transmitting a trusted portion of the mobile app including a trusted application to the mobile device, and installing the trusted portion of the mobile app on the mobile device thereby providing a trusted execution environment. Other systems and methods are disclosed.