Secure Element Customisable Functions Conversion Table
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Solution Overview
Problem
The TCG-TPM 2.0 standard for secure elements provides a finite set of predefined commands and functions, limiting the ability to access specific undefined functions or add personalized instructions, which is inadequate for the complex and demanding security needs of the automotive industry, particularly in systems with interconnected electronic control units.
Innovation Solution
A method and secure element design that allows loading of pre-established security functions and personalized functions into a non-volatile memory, enabling on-the-fly conversion and execution of operation codes using a conversion table, allowing for flexible and personalized functionality without modifying the secure element's mechanism or design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the TCG-TPM 2.0 standard commands are used, then security compliance is ensured, but functionality is limited to predefined commands only
Solution Approach 1:
The command set is segmented into two distinct parts: standard TPM 2.0 commands for security compliance and custom extended commands for enhanced functionality. The secure element processes different command types through separate instruction sets, allowing simultaneous adherence to standards and implementation of personalized functions.
Solution Approach 2:
An intermediary instruction conversion mechanism is introduced that translates custom operation codes into executable instructions. This intermediary layer enables the secure element to process both standard and personalized commands without compromising security protocols, acting as a bridge between standardized interfaces and customized functionality.
2Adaptability or versatility
If hard-coded execution is used, then execution speed is fast, but flexibility to add personalized functions is lost
Solution Approach 1:
The instruction set transitions from static hard-coded execution to dynamic loading from non-volatile memory. Instructions can be updated and personalized without hardware modification, enabling flexibility while maintaining fast execution through efficient memory access and conversion table lookups.
Solution Approach 2:
Personalized instructions are pre-loaded into non-volatile memory during manufacturing or configuration phases. This preliminary action allows the secure element to have personalized functions ready for immediate execution without compromising runtime performance or requiring on-the-fly compilation.
3Adaptability or versatility
If personalized instructions are added, then adaptability to specific needs is improved, but device complexity increases
Solution Approach 1:
Instead of implementing complex custom instruction processing logic, the system uses conversion tables that map custom operation codes to existing executable instructions. This copying approach allows personalized functionality to be achieved through lookup and translation rather than complex interpretation, reducing overall system complexity.
Data Source
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AI summary
The secure element (SEC) includes non-volatile memory (MEM) configured to store first instructions (ins_sec) for predefined security functions (FS) and at least one second instruction (ins_pers) for at least one other custom function (FP). A processing unit (CPU) is configured to execute at least one instruction (ins_k) from among the first instructions (ins_sec) and at least one second instruction (ins_pers).