Smartcard Memory Extension via Slave Card Segmentation
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Solution Overview
Problem
The limited memory capacity of smartcards restricts the amount of data and code that can be stored, often requiring code size reduction or feature removal to accommodate available memory, which is inadequate for storing user data and cryptographic programs.
Innovation Solution
A system utilizing a master smartcard and one or more slave smartcards, where the slave smartcards extend the memory capacity of the master smartcard by allowing their memory to be used as an extension, with commands and responses routed through the master smartcard for secure data management and authentication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the memory capacity of a smartcard is increased to store more user data and programs, then the storage capability is improved, but the code size reduction or feature removal becomes necessary to accommodate the limited memory space
Solution Approach 1:
The invention divides the memory storage system into multiple segments: the master smartcard retains its original memory for critical code and data, while slave smartcards provide additional memory capacity. This segmentation allows the system to overcome the memory limitation of individual smartcards without compromising the functionality or size of the code on the master card.
Solution Approach 2:
The master smartcard acts as an intermediary that manages access to both its own memory and the memory of slave smartcards. It intercepts memory access commands from the terminal, redirects appropriate commands to slave smartcards, and returns results transparently. This mediator approach enables extended storage capacity while maintaining the appearance of a unified memory space to the user.
2Quantity of substance
If multiple slave smartcards are used to extend memory capacity, then the storage space is improved, but the system complexity increases due to command redirection and authentication protocols
Solution Approach 1:
The master smartcard autonomously manages the complexity of communicating with multiple slave smartcards. It implements the authentication protocols, maintains mapping tables of virtual memory addresses to physical slave card locations, and handles command redirection without requiring the terminal or user to be aware of the underlying complexity. The system presents a simplified interface to the user while managing complex operations internally.
3Quantity of substance
If slave smartcards are integrated into the system, then the memory capacity is improved, but the security requirements increase due to the need for authentication and encryption between cards
Solution Approach 1:
Authentication between the master smartcard and slave smartcards is performed in advance, before any data access operations. The master card verifies the identity and credentials of slave cards, establishing secure communication channels beforehand. This preliminary authentication ensures that only authorized slave cards can be accessed, and all subsequent data transfers occur over verified secure connections, maintaining high security standards.
Data Source
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AI summary
A system (1), comprising a master smartcard (2) comprising a microcircuit (21) comprising computing means (22) and memory means (23) and a communication interface (24) able to communicate with a host terminal (4), and a host terminal (4) comprising computing means (41), a man machine interface (46), and at least one corresponding communication interface (42) able to communicate with said master smartcard (2), and at least one slave smartcard (3) comprising a microcircuit (31) comprising computing means (32) and memory means (33) and a communication interface (34) able to communicate with a host terminal (4), and the host terminal (4) comprising at least one corresponding communication interface (43) able to communicate with said slave smartcard (3), and said slave smartcard (3) being arranged so that its memory means (33) can be used as extension for the memory means (23) of the master smartcard (2).