Logic Gate Precharge Balancing for Side-Channel Leakage
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Solution Overview
Problem
Existing methods for protecting sensitive data in microcircuit devices against attacks like Simple Power Analysis, Differential Power Analysis, and Electromagnetic Analysis are inadequate as they still allow information leaks through logic gate switching patterns, which can be exploited by attackers.
Innovation Solution
A countermeasure method that involves modifying logic gates to be statistically balanced during a precharge phase by forcing all inputs except one to a specific value, using multiplexers and transistors to change the gate's functionality into a buffer or inverter, ensuring the output signal has a 50% probability of being 0 or 1, thereby masking the data processing patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a precharge phase with random binary data is supplied to logic circuit inputs, then the logic gates switch randomly to mask data processing patterns, but statistically unbalanced logic gates (AND, NAND, OR, NOR) still exhibit predictable switching patterns that leak information
Solution Approach 1:
The logic gate's functionality is made dynamic by allowing it to switch between two modes: during the precharge phase, it operates as a statistically balanced gate (XOR or XNOR) to mask information, and during the data processing phase, it operates as the original unbalanced gate (AND, NAND, OR, or NOR) to perform the required logic function. This dynamic reconfiguration resolves the contradiction by adapting the gate's statistical properties to the current operational phase.
Solution Approach 2:
The invention changes the statistical parameter of the logic gate by introducing control signals that modify the gate's behavior. During precharge, control signals force the gate to operate in a statistically balanced mode (50% probability of outputting 0 or 1), while during data processing, the control signals are adjusted to restore the original unbalanced statistical properties. This parameter change eliminates information leakage during precharge while preserving functional correctness during processing.
2Loss of information
If control signals are added to dynamically change logic gate functionality between precharge and data processing phases, then information leakage is reduced, but the device complexity and number of control signals increase
Solution Approach 1:
The invention applies periodic action by using phase signals that rhythmically switch the logic gate between two operational states: a first phase signal configures the gate for statistically balanced operation during precharge, and a second phase signal configures it for unbalanced operation during data processing. This periodic switching reduces information leakage while managing complexity through systematic, repeating control patterns.
Solution Approach 2:
The control mechanism is segmented into distinct phase signals that independently control different aspects of gate behavior. The first phase signal specifically controls the statistical balancing during precharge, while the second phase signal controls the functional operation during data processing. This segmentation allows precise control over when information masking is applied without requiring complex integrated control logic.
3Object-affected harmful factors
If the logic gate operates as a statistically balanced gate during precharge phase, then power consumption patterns and electromagnetic radiation are masked, but the gate cannot perform its intended logical function
Solution Approach 1:
The logic gate dynamically switches between two functional states based on the operational phase. During the precharge phase, it operates as a statistically balanced gate (XOR/XNOR) to mask power consumption and electromagnetic radiation patterns from SPA, DPA, and EMA attacks. During the data processing phase, it transitions to its original unbalanced configuration to perform the required logical function. This dynamic behavior resolves the contradiction by providing both security during precharge and functionality during processing.
Solution Approach 2:
The invention uses periodic phase signaling to alternately activate the gate's security mode and functional mode. The first phase signal activates the statistically balanced operation for attack resistance, while the second phase signal activates the original logical function. This periodic switching ensures that the gate provides both protection against cryptographic attacks and correct data processing functionality at appropriate times.
Data Source
AI summary
A countermeasure in a logic circuit having a logic gate supplying a binary output signal, the method including supplying binary data having random values to inputs of logic circuit during a precharge phase; supplying data to process to inputs of the logic circuit during a data processing phase; supplying on input of the logic circuit a precharge command signal launching a precharge phase; and under the effect of the precharge command signal, adapting the functioning of a logic gate of the logic circuit, statistically unbalanced, so that the output signal of the logic gate is in a binary state with a same probability as the random binary data supplied on input of the logic circuit during the precharge phase.