Secure Element Locking via File Access Profile Fingerprinting
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Solution Overview
Problem
Existing methods for locking secure elements, such as SIMs or UICCs, to mobile terminals are vulnerable to fraud as they can be easily tampered with by modifying the IMEI, leading to unauthorized access to mobile communications networks, especially in unattended M2M devices.
Innovation Solution
The method involves creating a unique 'fingerprint' for each mobile terminal by monitoring and hashing the file access profile during the start-up sequence, comparing it to a nominal fingerprint stored on the secure element, and blocking further operation if they do not match, thereby ensuring secure element operation is restricted to the originally paired terminal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If IMEI-based locking is used, then secure element can be locked to mobile terminal, but IMEI can be modified to allow rogue terminal access
Solution Approach 1:
The patent introduces a file access profile as an intermediary mechanism between the secure element and the mobile terminal. Instead of directly trusting the IMEI, the system monitors and verifies the sequence of file accesses on the secure element during terminal startup. This intermediary verification process ensures that even if the IMEI is modified, the rogue terminal cannot access the secure element because its file access pattern will not match the expected profile stored in the secure element.
Solution Approach 2:
The patent replaces the simple mechanical IMEI verification mechanism with a more complex software-based verification system. Instead of merely comparing IMEI strings, the system implements a multi-step verification process that includes monitoring APDU commands, tracking file access sequences, and comparing against stored profiles. This substitution of the verification mechanism significantly increases security while maintaining the locking function.
2Measurement precision
If file access profile monitoring is implemented, then terminal identification accuracy increases, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-storing the expected file access profile in the secure element during the legitimate pairing process. The secure element records the sequence of file accesses that occur during normal terminal startup and stores this profile beforehand. During subsequent verification, the system simply compares the actual access sequence against this pre-stored profile, eliminating the need for complex real-time analysis and reducing operational complexity.
Solution Approach 2:
The secure element performs self-verification by autonomously monitoring its own file access patterns and comparing them against the expected profile stored within itself. This self-service approach eliminates the need for external verification systems or complex server-side processing, significantly reducing overall system complexity while maintaining high identification accuracy.
Data Source
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AI summary
The invention relates to methods and devices for locking a secure element (20), such as a subscriber identity module (SIM) or a universal integrated circuit card (eUICC/UICC), to a mobile terminal (14). According to the invention the order in which a mobile terminal, for instance, during the start-up sequence of the mobile terminal (14), accesses files (26a, 26b, 27a, 27b, 28a) stored on the secure element (20) is used as a kind of fingerprint of the mobile terminal (14). Preferably, the fingerprint is derived from the file access profile of the mobile terminal (14) by applying a hash function to the file access profile. If the fingerprint derived from the file access profile of the mobile terminal (14) differs from a nominal fingerprint, then it is concluded that the mobile terminal (14) is not the mobile terminal the secure element (20) has been locked to originally. Otherwise, i.e. if the fingerprint of the mobile terminal (14) is identical to the nominal fingerprint, it is concluded that the mobile terminal (14) is the mobile terminal the secure element (20) has been locked to originally.