Randomizing Current Injection Circuit to Obscure Gate Noise
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Solution Overview
Problem
Current security systems for integrated circuits, particularly those using code-protected internal memories, are vulnerable to non-invasive physical attacks like differential power analysis (DPA), which can reveal confidential information by monitoring power consumption or noise emissions, and existing countermeasures using randomly generated signals derived from a single synchronous clock source are ineffective against advanced statistical analyses.
Innovation Solution
An asynchronously controlled current noise generator is introduced, utilizing both synchronous and asynchronous clock sources and a random number generating circuit to create randomly changing digital control signals that obscure gate switching noise, altering current and emission profiles to protect against external monitoring, employing multiple current sources and a bitstream buffer to vary current amplitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If randomly generated signals derived from a single synchronous clock source are used to prevent DPA, then noise is introduced to obscure power consumption traces, but advanced statistical analyses can still overcome such approaches and reveal confidential information
Solution Approach 1:
The single synchronous clock source is segmented into multiple independent clock sources (first synchronous clock source and asynchronous clock source), each generating random control signals that are combined to control current sources. This segmentation prevents statistical analysis from predicting the combined noise pattern, as the asynchronous nature of at least one clock source introduces unpredictability that cannot be correlated through traditional DPA methods.
Solution Approach 2:
The patent creates a composite noise signal by combining outputs from multiple clock sources (synchronous and asynchronous) that control multiple current sources. This composite approach merges different temporal characteristics and randomness sources, creating a noise profile that is more resistant to statistical analysis than single-source noise, similar to how composite materials combine properties of constituent materials to achieve superior characteristics.
2Object-affected harmful factors
If multiple current sources with varying amplitudes are used to obscure gate noise, then security against monitoring activities is improved, but device complexity and circuit configuration increase
Solution Approach 1:
The patent implements dynamic control of current sources by using random control signals from multiple clock sources to continuously vary the activation state and amplitude of multiple current sources. This dynamic behavior creates a time-varying noise profile that adapts unpredictably, making it impossible for monitoring equipment to establish a stable baseline or detect pattern correlations that would reveal encrypted data.
Solution Approach 2:
The patent changes key parameters of the current sources including amplitude (through different current source strengths), timing (through asynchronous clock signals), and activation patterns (through random control signals). By varying these parameters dynamically and independently across multiple current sources, the system creates a complex noise environment that obscures the electromagnetic signatures of gate switching activities.
Data Source
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AI summary
A circuit for obscuring gate switching noise includes a synchronous clock source; an asynchronous clock source; at least one current source; and a random number generating circuit for receiving clock inputs from the synchronous clock source and the asynchronous clock source, the random number generating circuit generating randomly changing asynchronous digital control signals for controlling the current source.