Smart Card Display Interception Circuit for Transaction Data
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Solution Overview
Problem
EMV standard-compliant bank cards lack additional input/output ports, making it impossible to drive a display for showing last transactions due to security restrictions, which is a challenge for incorporating a screen to display transaction information.
Innovation Solution
A second microcontroller is added to the smart card to intercept and store transaction information, along with an electronic display, battery, and command interception circuit, allowing the display of last transactions without compromising security by using existing communication standards like ISO7816 or ISO14443.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EMV standard-compliant chips are used with restricted communication interfaces, then security is improved, but the ability to display transaction information is worsened
Solution Approach 1:
The card system is divided into two independent microcontrollers: the secure EMV chip (first microcontroller) that handles only secure transactions, and a second microcontroller that handles display operations. This segmentation allows each component to perform its specialized function without compromising security while enabling display capability.
Solution Approach 2:
The second microcontroller acts as an intermediary between the secure EMV chip and the display screen. It intercepts transaction data from the secure chip through shared memory and processes it for display, thereby mediating between the security-restricted chip and the display requirement without adding communication interfaces to the secure chip.
2Adaptability or versatility
If additional input/output ports are added to EMV chips, then display functionality is improved, but security is worsened
Solution Approach 1:
The display interface functionality is extracted from the secure EMV chip and placed in a separate second microcontroller. This extraction removes the need for additional I/O ports on the secure chip, maintaining its security restrictions while enabling display capability through the separate component.
Solution Approach 2:
The second microcontroller serves multiple functions: it acts as a display controller, a data interceptor from the secure chip, and a power management unit. This multi-functionality provides the needed display interface without requiring modifications to the secure EMV chip.
3Adaptability or versatility
If a second microcontroller is added to intercept and store transaction information, then display capability is improved, but device complexity is worsened
Solution Approach 1:
The second microcontroller combines multiple functions into a single component: display control, data interception from the secure chip, and local data storage. This merging reduces the overall system complexity compared to having separate dedicated components for each function.
Solution Approach 2:
The second microcontroller is integrated within the card body alongside the secure EMV chip, with both microcontrollers sharing the same physical substrate and power supply. This nesting approach minimizes the increase in device complexity by utilizing existing card infrastructure.
Data Source
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Figure 3
AI summary
To allow the display of the latest transactions performed, a chip card 100c comprises at least one secure chip 101c furnished with at least one communication interface so as to be able to communicate with a card reader so as to perform a transaction. The card furthermore comprises an electronic display 103, an autonomous battery 104, and an interception circuit 150c linked to the at least one communication interface of the secure chip so as to be able to intercept at least one type of command and store at least one item of information so as to be able to display it on the display.