Secure SIM Data Storage via WEF Chaining and Segmentation
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Solution Overview
Problem
Secure storage of data on mobile devices is challenging due to the risk of information extraction via operating system privilege, necessitating a method to securely store data on a SIM card that is inaccessible to normal means and forensic devices.
Innovation Solution
The method involves analyzing the SIM card's filesystem, identifying writable segments, and securely storing data using WEF chaining and Remote File Management protocol, ensuring data is hidden from inspection and unique to each SIM, with the Secure SIM Server managing allocation and access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If data is stored on mobile device operating system, then data storage is convenient and accessible, but data security is compromised due to potential extraction via privilege escalation
Solution Approach 1:
The patent extracts data storage from the vulnerable operating system environment and relocates it to the SIM card's secure element. The SIM card's secure storage mechanism is isolated from the main device OS, preventing privilege escalation attacks while maintaining data accessibility through secure protocols.
Solution Approach 2:
The SIM card acts as an intermediary between the user and sensitive data. Instead of direct access to data on the device, users interact with the SIM card's secure storage, which mediates access requests and enforces security policies, thereby protecting data from direct OS-level attacks.
2Ease of manufacture
If data is stored in standard SIM filesystem, then storage is simple and compatible, but data becomes visible to forensic inspection tools
Solution Approach 1:
The patent segments the SIM card storage into multiple virtual files and scattering data across different physical locations within the SIM filesystem. This segmentation makes forensic reconstruction difficult while maintaining simple storage operations through virtual file management.
Solution Approach 2:
The patent employs asymmetric encryption where data is encrypted with a key that only the authorized application can access. The encrypted data appears as random bytes to forensic tools, creating asymmetry between the legitimate access path (encrypted and secure) and the forensic inspection path (only reveals random data).
3Productivity
If multiple applications share SIM storage, then storage utilization is efficient, but cross-application data leakage becomes possible
Solution Approach 1:
The patent assigns different security contexts and encryption keys to different applications accessing the SIM card. Each application has its own secure namespace with localized security properties, ensuring that while storage is shared physically, data remains isolated logically through application-specific security contexts.
4Adaptability or versatility
If SIM storage structure follows GSM standards, then compatibility is maintained, but flexibility for secure custom storage is limited
Solution Approach 1:
The patent nests a custom secure file system structure within the standard GSM SIM filesystem. The custom secure storage operates as a nested layer that appears as standard SIM files to external systems but provides enhanced security and flexibility internally through virtual file management and encryption.
Data Source
AI summary
Embodiments of the invention provide systems and methods for analyzing a Subscriber Identity Module (SIM) card, ascertaining multiple distally separated storable sections, and then securely storing data as an ordered list of storable sections representing a concatenated available storage on the SIM.