Portable Data Carrier Blocking via Continuous Random Write Masking
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Solution Overview
Problem
Portable data carriers, such as smart cards, are vulnerable to attacks like Simple Power Analysis and Differential Power Analysis, which disrupt their functioning by analyzing power consumption, and existing protection mechanisms can be detected and bypassed by attackers.
Innovation Solution
Implementing a method where continuous write accesses are performed at randomly consecutive times to lock the data carrier, masking the power consumption pattern of the locking access among regular write accesses, using a non-volatile memory to ensure the blocking mark is not deleted by power interruption, and blocking security-critical applications or memory accesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a blocking flag is written to non-volatile memory to block the data carrier, then the data carrier is protected from attacks, but the power consumption increases and becomes detectable by attackers
Solution Approach 1:
The patent implements continuous write accesses to the non-volatile memory at randomly consecutive times, regardless of whether an attack is detected or not. This continuous writing activity masks the power consumption pattern of the blocking flag write operation, making it indistinguishable from normal operational writes. The useful action of writing continues uninterrupted, thereby hiding the security-related write from power analysis.
Solution Approach 2:
The patent introduces an intermediary mechanism of continuous random writes that acts as a mediator between the normal operational writes and the security blocking write. This intermediary activity creates a power consumption pattern that obscures the true intent of the blocking write, preventing attackers from detecting when the data carrier is being blocked.
2Reliability
If the data carrier is blocked by writing a locking flag, then security is enhanced, but the locking mechanism can be detected and bypassed by analyzing power consumption history
Solution Approach 1:
By maintaining continuous write accesses to the non-volatile memory at randomly consecutive times, the system creates a steady-state power consumption pattern that does not reveal the moment of blocking. The continuous action ensures that the blocking write is buried within the normal operational writes, making detection difficult.
Solution Approach 2:
The system performs preliminary write accesses continuously before the actual blocking event. These preliminary writes establish a baseline power consumption pattern that continues during the blocking operation, thereby preparing the power consumption profile to mask the blocking write from detection.
3Difficulty of detecting and measuring
If write accesses are performed continuously to mask power consumption, then the locking mechanism is hidden, but the device complexity increases
Solution Approach 1:
The control mechanism is designed to handle multiple functions through a unified approach. The same continuous write access mechanism serves both normal operational purposes and security blocking purposes. By making the write mechanism universal, the system avoids adding separate complex control logic for masking power consumption.
Solution Approach 2:
The system dynamically adjusts the timing and targeting of write accesses based on operational state. The control mechanism uses random timing and selective addressing to dynamically mask the blocking write, rather than using a fixed complex pattern. This dynamic approach simplifies the control logic while maintaining effectiveness.
Data Source
Figure 1A~1B
Figure 2
AI summary
The method involves implementing of write accesses on a memory of the data carrier continuously to the arbitrary one on the other subsequent points of typing hours. The data carrier is partially blocked by the continuous implemented write accesses. An independent claim is also included for a portable data carrier.