Smart Card Non-Volatile Memory Write Address Management
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Solution Overview
Problem
Smart cards face limitations in writing large amounts of data due to the small buffer size and the T=0 protocol's 255-byte data limit, requiring cumbersome address calculations for writing data exceeding this limit, especially impractical for biometric data like fingerprints or facial recognition data.
Innovation Solution
A method where the smart card compares an object identification parameter in a write command with a stored parameter, writing data to a predefined or default address, calculating and storing a new address based on the data size, allowing seamless writing of data exceeding the buffer size without external calculation of addresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If data is divided into smaller subsets to exceed the 255-byte limit, then large amounts of data can be written to the card, but the complexity of address calculation and command construction increases significantly
Solution Approach 1:
The patent divides large data into smaller subsets that fit within the 255-byte limit of T=0 protocol commands. Each subset is written sequentially to the transparent file using UPDATE BINARY commands with incrementing offsets. This segmentation allows writing large amounts of data while managing the complexity through systematic subdivision rather than requiring complex address calculations for each write operation.
Solution Approach 2:
The patent performs preliminary actions by establishing a base offset value that is stored in the smart card's non-volatile memory. This base offset represents the starting position for subsequent writes. By pre-configuring this reference point, the system eliminates the need for complex address calculations during data writing, as each subsequent write simply adds to this pre-established base.
2Ease of manufacture
If UPDATE BINARY command is used for writing to transparent file, then data can be written at specific addresses, but the sending entity must calculate both data subsets and target addresses which is impractical
Solution Approach 1:
The patent implements self-service by having the smart card itself manage the address calculation and offset tracking. The card stores the base offset in its non-volatile memory and automatically calculates the correct write positions by adding to this stored base. This transfers the computational burden from the external sending entity to the smart card, making the operation much easier for the user while maintaining precise address management.
Solution Approach 2:
The patent introduces an intermediary mechanism in the form of a base offset value stored in the smart card's non-volatile memory. This base offset acts as a mediator between the simple UPDATE BINARY command and the complex address management requirements. By establishing this intermediate reference point, the system simplifies the interface between the external entity and the internal file system, making operations easier while maintaining address precision.
3Adaptability or versatility
If record-based UPDATE RECORD command is used, then records can be created with indexes, but calculating record indexes is impractical and data structure becomes highly impractical when reading blocks of different sizes
Solution Approach 1:
The patent inverts the traditional record-based approach by using a transparent file with sequential offset-based writing instead of indexed records. Rather than creating records with indexes that require calculation and management, the system uses a simple transparent file structure where data is written sequentially at offsets calculated from a stored base. This inversion eliminates the complexity of index calculation while maintaining the ability to handle variable-size data blocks efficiently.
Data Source
AI summary
A smart card compares an object identification parameter associated with a write command with an object identification parameter stored in the non-volatile memory of the smart card. If the comparison is positive, the data embedded in the write command is written at a at a predefined address whose value is stored in the non-volatile memory, an address corresponding to the sum of the stored predefined address and the size of the written data is calculated, and the calculated address is stored in the non-volatile memory in place of the predefined address. If the comparison is negative, the data is written at a default address, an address corresponding to the sum of the default address and the size of the written data is calculated, and the calculated address is stored in the non-volatile memory as the predefined address.