eSIM Restoration via Secure Element Backup
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Solution Overview
Problem
Existing methods for restoring a deleted or corrupted electronic Subscriber Identity Module (eSIM) on a mobile device are inefficient, as they require users to contact the mobile network operator for replacement, and storing a backup eSIM poses security risks due to the untrusted nature of the mobile device.
Innovation Solution
The secure element on the mobile device creates a table of instantiated eSIMs and stores a backup data blob encrypted with a unique key, allowing for authorized decryption and re-installation of the eSIM, ensuring the uniqueness and security of the eSIM credentials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a backup eSIM is stored on the mobile device for restoration purposes, then restoration efficiency is improved, but security is worsened due to the untrusted nature of the mobile device
Solution Approach 1:
The system separates the eSIM backup into two distinct components: the encrypted data blob stored in the untrusted mobile device environment and the decryption key stored exclusively in the trusted secure element. This segmentation allows the backup to be stored efficiently in the main memory while maintaining security through the secure element's exclusive control of the decryption key, resolving the contradiction between restoration efficiency and security.
2Ease of operation
If the mobile device stores eSIM credentials in clear text for easy restoration, then ease of operation is improved, but security is worsened due to exposure of sensitive data
Solution Approach 1:
The system performs preliminary encryption of the eSIM data blob using a key derived from the secure element's credentials before storing it in the untrusted mobile device environment. This preliminary action ensures that even if the stored data is accessed by unauthorized parties, the sensitive credentials remain protected. The restoration process remains easy because the secure element automatically handles the decryption when the data blob is presented, eliminating the need for manual security management by the user.
3Speed
If eSIM restoration is performed without verification of uniqueness, then restoration speed is improved, but reliability is worsened due to potential duplicate installations
Solution Approach 1:
The system implements a feedback mechanism where the secure element verifies whether the eSIM credentials in the data blob are already installed before allowing restoration. The secure element checks its inventory of installed eSIMs and only permits restoration if the credentials are not present. This feedback loop ensures uniqueness while maintaining fast restoration speeds because the verification is performed automatically by the secure element's cryptographic operations rather than through manual user verification.
Data Source
AI summary
A secure element uses a backup context to restore a deleted electronic Subscriber Identity Module (eSIM) without compromising a trust relationship with a mobile network operator (MNO). A backup copy of a data binary large object (data blob) originally used to instantiate the eSIM is retrieved. The secure element determines if the eSIM within the data blob is uniquely associated with the secure element from a previous installation. The secure element examines the data blob to determine an identifier unique to the eSIM. The identifier can be an integrated circuit card identifier (ICC-ID) or a profile identifier. The secure element searches a table of instantiated eSIMs in the secure memory. If the secure element is able to match the recovered eSIM identifier with an entry in the table, then the secure element installs this eSIM in the secure element.