Data-Gating Masking with Async Handshakes to Block Glitches
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Solution Overview
Problem
Existing cryptographic implementations are vulnerable to power analysis attacks due to dynamic hazards that cause information leakage through unwanted spikes in gate outputs, known as glitches.
Innovation Solution
Implement asynchronous gating elements and synchronization protocols using random synchronization tokens to control data flow, ensuring computations are complete before allowing data propagation, thereby preventing glitches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hardware masking techniques are used to protect against power analysis attacks, then security is improved, but dynamic hazards cause information leakage through glitches
Solution Approach 1:
The patent introduces asynchronous gating elements as intermediary components between masked operations. These gating elements act as mediators that control the flow of masked data, enabling data to pass only when synchronization tokens indicate that previous operations are complete, thereby preventing glitch propagation while maintaining security
Solution Approach 2:
The patent implements preliminary synchronization by requiring completion tokens to be generated and verified before masked data is allowed to propagate through gating elements. This preliminary action ensures that all previous masked operations have finished before new data flows, preventing dynamic hazards from causing information leakage
2Object-generated harmful factors
If asynchronous gating elements are used to prevent glitch propagation, then information leakage is reduced, but device complexity increases
Solution Approach 1:
The patent segments the cryptographic circuit into multiple independent masked operations, each with its own asynchronous gating elements and synchronization tokens. This segmentation allows each operation to be controlled independently, preventing glitch propagation between operations while keeping each segment's complexity manageable
Solution Approach 2:
The patent implements feedback mechanisms where completion tokens are generated based on the status of previous operations and fed back to control the gating elements. This feedback ensures that data only propagates when appropriate, reducing information leakage while using a systematic approach to manage complexity
3Object-generated harmful factors
If completion detection is implemented to control data flow, then glitch propagation is prevented, but processing time increases
Solution Approach 1:
The patent uses dynamic asynchronous gating elements that adapt their behavior based on real-time completion status indicated by synchronization tokens. Rather than using fixed synchronous timing, the system dynamically enables data flow only when necessary, preventing glitches while minimizing unnecessary delays
Data Source
AI summary
A bundled-data protocol can be used to synchronize the data flow in the mask shares. A random synchronization token is input and “bundled” with the combinatorial logic of a share. An additional output from the combinatorial logic is also provided such that when the original combinational output is exclusive OR'd (XOR'd) with the additional output yields the random synchronization token. When the XOR of the original and additional outputs, and the input synchronization token are equal, it indicates that the computation of the combinatorial logic is complete. Thus, the result of the comparison of the XOR of the original and additional outputs, and the input synchronization token may be used as a “done” or “enable” handshake signal to allow asynchronous gating elements (e.g., AND gates, asynchronous set-reset latches, and/or state-holding elements like the Muller C-element, etc.) to start and stop the flow of data in a mask share.