Personalization Data Introduction in WLCSP IC Cards
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Solution Overview
Problem
In the production of secure integrated circuit cards, such as eUICC, the challenge lies in efficiently introducing personalization data, particularly unpredictable data, into non-volatile memories using Wafer Level Chip Scale Packaging (WLCSP) techniques, where the conversion function is unknown, and traditional methods like administrative APDUs are time-consuming or not feasible.
Innovation Solution
A method involving the storage of Token Non-Volatile Memory Images, where a subset of personalization data is encoded using a known coding scheme, and a decoding software circuit is provided to decode and execute the inner command script at activation, allowing for the writing of personalization data values in the non-volatile memory without prior knowledge of storage locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional administrative APDUs are used to introduce personalization data, then data can be written to non-volatile memory, but the process becomes time-consuming and not feasible for WLCSP production
Solution Approach 1:
The patent applies preliminary action by pre-generating Token Non-Volatile Memory Images that contain encoded personalization data during the wafer fabrication process itself, rather than performing time-consuming APDU operations after the chip is packaged. This allows personalization data to be introduced in advance during manufacturing, enabling high-volume WLCSP production without subsequent time-consuming programming steps.
Solution Approach 2:
The patent replaces the mechanical/Administrative APDU-based personalization system with an automated encoding system that writes Token Non-Volatile Memory Images directly to the non-volatile memory during wafer-level processing. This substitution enables parallel processing of multiple chips simultaneously, dramatically improving productivity while eliminating the sequential time constraints of traditional APDU methods.
2Reliability
If personalization data storage locations are kept unknown for security, then security is improved, but the complexity of managing and writing data increases
Solution Approach 1:
The patent introduces an intermediary encoding mechanism that translates known personalization data into Token Non-Volatile Memory Images with obfuscated storage locations. This intermediary layer maintains security by keeping actual data locations unknown while allowing the system to manage personalization data through standardized encoding processes, thus balancing security requirements with manageable complexity.
Solution Approach 2:
The patent applies parameter changes by transforming personalization data into encoded Token Non-Volatile Memory Images where the storage location parameter is deliberately obscured or randomized. This parameter transformation maintains security through unknown storage locations while the encoding process itself provides a systematic method for managing the data, reducing the perceived complexity through standardized procedures.
3Ease of manufacture
If WLCSP techniques are used for packaging, then area and cost are optimized, but the ability to introduce personalization data after packaging is limited
Solution Approach 1:
The patent applies preliminary action by performing personalization data encoding and writing Token Non-Volatile Memory Images during the wafer-level packaging process itself, before the chips are individually packaged. This ensures that even with WLCSP's limited post-packaging access capabilities, personalization data is successfully introduced during manufacturing, maintaining both packaging efficiency and personalization capability.
Solution Approach 2:
The patent merges the personalization data introduction process with the WLCSP packaging process by performing both operations during wafer-level processing. This combination allows the benefits of WLCSP (area optimization and cost reduction) to be realized while simultaneously completing personalization data introduction, eliminating the need for separate post-packaging programming steps.
Data Source
AI summary
In embodiments, a method is provided that includes writing a static data image in an invariant part of a non-volatile memory of an integrated circuit used to store an operating system; writing a set of personalization data in the static data image representing data specific to the integrated circuit; storing a subset of the set of personalization data in a reserved area of the non-volatile memory by reserving the reserved area and storing commands for writing the set of personalization data by an application or the operating system; converting the commands with a known code to obtain an inner command script, the inner script including the commands as encoded; storing the inner command script in the reserved area of the non-volatile memory; decoding and executing the inner command script to obtain the commands during an activation of the integrated circuit; and executing the commands by the integrated circuit.