Trusted Execution Environment for Secure Subscriber Device Access

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Solution Overview

Problem

Telecommunication service providers face challenges in preventing unauthorized access and usage of their proprietary services and devices, as tech-savvy consumers employ software and hardware hacks to bypass security measures and unlock devices, leading to unanticipated deviations from expected service usage and device purchases.

Innovation Solution

Implementing a trusted execution environment (TEE) in communication devices, which includes a secure partition that operates independently of the main operating system, using Trustlet applications to authenticate and manage access, and collaborating with a policy engine and user interface components to enforce service provider policies, allowing for secure over-the-air provisioning and device management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional security measures are used to prevent unauthorized access, then device security is maintained, but consumers can still bypass security through software and hardware hacks

Engineering Contradiction:
Improvedevice securityVSAvoidunauthorized access
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent divides the device into two independent execution environments: a secure execution environment (TEE) and a non-secure execution environment (NEE). The TEE is further segmented into a secure boot environment for authentication and a trusted execution environment for policy enforcement. This segmentation isolates security-critical functions from the main OS, preventing hacks in the NEE from compromising device security.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a policy engine as an intermediary component that mediates between the secure execution environment and the non-secure execution environment. The policy engine receives authentication results from the TEE and enforces access control policies, acting as a buffer that prevents unauthorized access even if security measures are bypassed.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a trusted execution environment is implemented to prevent unauthorized access, then security is enhanced, but device complexity increases

Engineering Contradiction:
Improveaccess controlVSAvoidexecution environment structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The secure execution environment is designed as a universal platform that can enforce multiple types of access control policies (carrier lock, device lock, service lock) through a single unified architecture. The Trustlet applications can be configured to implement different policy types, making the system multi-functional without requiring separate complex systems for each control mechanism.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent implements a nested structure where the secure boot environment is nested within the trusted execution environment, which is nested within the non-secure execution environment. Each nested layer has specific authentication and authorization functions, allowing complex security policies to be implemented through layered containment rather than a single complex system.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Reliability

If carrier lock and device lock policies are enforced, then unauthorized service access is prevented, but user flexibility is reduced

Engineering Contradiction:
Improveservice access controlVSAvoiduser service choice
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The access control system is designed to be dynamic rather than static. The policy engine can evaluate multiple conditions (service provider, device state, user authentication) and dynamically adjust access rights. Users can be granted temporary access to different services based on real-time conditions, allowing flexibility within the framework of carrier and device lock policies.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system allows changing access control parameters (such as allowed service providers, device states, or user permissions) without requiring changes to the fundamental security architecture. The policy engine can modify access rights by changing policy parameters, enabling flexible service access control while maintaining the integrity of the trusted execution environment.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2839690B1Secure environment for subscriber device
Publication Date: 2021.08.25 T MOBILE US INC
  • EP2839690B1 patent drawingFigure 1
  • EP2839690B1 patent drawingFigure 2
  • EP2839690B1 patent drawingFigure 3

AI summary

A secure operating environment for a telecommunication device is disclosed, where a trusted execution environment (TEE) can establish both first secure communication (SC) channel between the TEE and a security-enabled SIM card, and a second SC between a service provider entity and Trustlet application, which is a component of the TEE of the telecommunication device. The telecommunication device may include a processor(s), an identification module, and a memory including the TEE and a normal operating environment (NOE). The TEE can be operated by the one or more processors to establish the first SC channel, authenticate a service identifier of the identification module, and establish the second SC channel, prior to an execution of the NOE.