SIM Unlock Verification via Secure Boot Mode

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Solution Overview

Problem

Current methods for verifying the validity of SIM unlock messages in mobile terminals are vulnerable to unauthorized access, allowing third parties to provide SIM unlock codes, compromising security.

Innovation Solution

The method involves verifying the validity of a SIM unlock message during the boot mode by checking digital signatures and certificates using pre-stored public keys, ensuring only authorized entities can modify the SIM unlocking restrictions, thereby enhancing security and integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If SIM unlock codes are generated using a mathematical formula from IMEI or MCC codes, then ease of operation is improved, but security is worsened as unauthorized third parties can derive the codes

Engineering Contradiction:
ImproveSIM unlock code generationVSAvoidsecurity
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent extracts the security verification process from the runtime mode and places it in the boot mode, where the terminal is more secure. By separating the verification function into a dedicated secure environment (boot mode) with restricted access, the system maintains ease of operation while improving security against unauthorized code derivation.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a certificate verification mechanism as an intermediary between the SIM unlock code and the terminal's security system. The certificate, verified during boot mode, acts as a trusted mediator that authenticates the source of the unlock code, preventing unauthorized third parties from using mathematically derived codes even if they know the IMEI or MCC.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If SIM unlock verification is performed in runtime mode, then ease of operation is improved, but security is worsened due to potential unauthorized access

Engineering Contradiction:
Improveverification processVSAvoidsecurity
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent performs the security verification action in advance during the boot mode before the terminal enters runtime mode. By completing the certificate verification and SIM unlock authentication during boot, the system ensures security is established before any runtime operations occur, preventing unauthorized access during the more vulnerable runtime period.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent inverts the conventional approach by performing security verification in boot mode rather than runtime mode. Instead of verifying during normal operation when the system is more accessible, the verification is moved to the boot phase where the terminal has fewer active processes and more restricted access, thereby improving security while maintaining operational ease.

Inventive Principle:
Principle #13The other way round (Inversion)

3Reliability

If random SIM unlock codes are stored securely on the terminal and network, then security is improved, but device complexity increases due to secure storage requirements

Engineering Contradiction:
ImprovesecurityVSAvoidsecure storage system
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent makes the boot mode serve multiple functions: it not only initializes the terminal but also performs security verification and certificate validation. By making the boot mode multi-functional, the system utilizes an existing secure environment for additional security purposes without adding separate dedicated hardware or software modules, thereby improving security while minimizing the increase in device complexity.

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

Solution Approach 2:

The terminal performs its own security verification during boot mode using pre-stored certificates and public keys. The system is self-sufficient in validating SIM unlock codes without requiring continuous external verification services, reducing the need for complex external secure storage infrastructure while maintaining high security standards.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP2165503B1Received message verification
Publication Date: 2017.10.11 VODAFONE GRP PLC
  • EP2165503B1 patent drawingFigure 1
  • EP2165503B1 patent drawingFigure 2
  • EP2165503B1 patent drawingFigure 3

AI summary

A method of verifying the validity of a message received by a telecommunications terminal (8) having a processor (30) and which is operable in a boot mode and a runtime mode is disclosed. In the embodiments the message is a SIM unlock message, for removing or modifying a restriction of the types of subscriber identity module (SIM) with which the mobile terminal may be used. In response to reception of the SIM unlock message when the terminal (1) is in the runtime mode, the processor 30 of the terminal (1) causes the terminal to enter the boot mode and verify the validity of the message during the boot mode. Because the validity of the message is checked during the boot mode, the check can be performed with greater security.