Signal-Layer Resistor Divider for IC Tamper Detection
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Solution Overview
Problem
Configurable integrated circuits are vulnerable to physical attacks that circumvent security protections by accessing signal layers, posing a risk to secure signals and valuable information stored in transistor layers.
Innovation Solution
An anti-tamper circuit is implemented using a resistor divider formed by conductors in the signal layers, with a profiling mode to set a detection voltage and a protection mode to compare it against a stored value, generating an alert signal upon resistance changes indicative of tampering, which can trigger security responses such as IC reset or memory clearing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If signal layers are made accessible for configuration purposes, then ease of operation is improved, but security protection deteriorates due to vulnerability to physical attacks
Solution Approach 1:
The patent implements a profiling mode that executes before normal operation to establish baseline resistance values for conductors in signal layers. This preliminary measurement creates reference data that enables later detection of tampering, allowing the system to prepare security defenses in advance while maintaining normal configuration access
Solution Approach 2:
The patent introduces an intermediary detection mechanism that monitors resistance changes in signal layer conductors without blocking configuration access. This intermediary layer of monitoring allows legitimate operations to proceed while detecting malicious physical attacks, resolving the contradiction between accessibility and security
2Object-affected harmful factors
If anti-tamper monitoring is implemented in signal layers, then security protection is improved, but device complexity increases due to additional circuitry
Solution Approach 1:
The patent makes existing signal layer conductors serve dual purposes: their primary function for signal transmission and their secondary function as security monitoring elements by measuring their electrical resistance. This multi-functionality approach enables tamper detection without requiring completely separate dedicated security circuits, thereby limiting the increase in device complexity
Solution Approach 2:
The patent monitors changes in electrical resistance parameters of existing conductors to detect tampering. By utilizing changes in an existing physical parameter (resistance) rather than introducing new monitoring components, the system achieves improved security while minimizing additional circuit complexity
3Measurement precision
If resistance measurement is used for tamper detection, then measurement precision is improved, but energy consumption increases due to continuous monitoring
Solution Approach 1:
The patent implements periodic resistance measurements rather than continuous monitoring, executing profiling measurements at specific intervals or triggered by specific events. This periodic approach maintains measurement precision for tamper detection while significantly reducing overall energy consumption compared to continuous monitoring schemes
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively detects physical attacks on integrated circuits by monitoring voltage changes across the resistor divider, enabling immediate security measures to prevent unauthorized access and system execution.
Implementation Method 1
A resistance value is selected for the resistor divider during a profiling mode to generate a detection voltage. During a protection mode, anti-tamper compare logic circuitry in the IC die compares the detection voltage generated by the resistor divider to the detection voltage stored in the lock-step circuit to determine if a physical attack has occurred
Data Source
AI summary
An integrated circuit includes an anti-tamper circuit having a resistor. The resistor includes conductors in a conductive layer of the integrated circuit. Each of the conductors extends across a width of the integrated circuit. The conductors are spaced apart across a length of the integrated circuit. The anti-tamper circuit generates an output signal indicative of changes in a resistance of the resistor caused by tampering that affects the conductors.