Cipher Accelerator With Redundant Rounds for Tamper Protection
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Solution Overview
Problem
Cryptographic processes are vulnerable to Voltage Glitch Attacks, which can cause integrated circuits to generate incorrect outputs and leak information, necessitating effective tamper protection mechanisms.
Innovation Solution
A cipher accelerator with a cryptographic circuit that executes normal and redundant rounds, using a controller to manage round sequences and compare results to ensure consistency, and employs a double-inspection mechanism to detect faults in critical clock cycles, enhancing security and reducing execution time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional cryptographic operations are used without redundant rounds, then the execution time is short, but the system becomes vulnerable to Voltage Glitch Attacks and differential fault analysis
Solution Approach 1:
The cryptographic operation is divided into multiple independent rounds (normal rounds and redundant rounds). Each round processes a portion of the cryptographic calculation, allowing the system to detect faults in specific segments without requiring complete re-execution of all rounds. This segmentation enables targeted fault detection while minimizing overall execution time overhead.
Solution Approach 2:
Redundant rounds are prepared and executed in advance alongside normal rounds, before the final cryptographic result is produced. The system performs preliminary fault detection by comparing intermediate results from redundant rounds with normal rounds, allowing early termination and error detection before completing the entire cryptographic operation, thus reducing the effective time penalty.
2Productivity
If all normal rounds are executed sequentially before redundant rounds, then the fault detection is simple, but the execution time increases significantly
Solution Approach 1:
The execution sequence of rounds is made dynamic rather than fixed. The controller randomly selects and adjusts the sequence in which normal and redundant rounds are executed, changing the timing and order based on operational requirements. This dynamic approach prevents attackers from predicting when faults will occur and maintains security while optimizing execution time through flexible scheduling.
Solution Approach 2:
Redundant rounds are periodically interspersed among normal rounds at predetermined intervals rather than being executed in a single block. This periodic insertion of verification rounds allows continuous fault detection throughout the cryptographic operation, maintaining security without requiring a complete separate verification phase, thus improving overall productivity.
3Reliability
If the sequence of normal and redundant rounds is fixed, then the control logic is simple, but attackers can predict and manipulate specific rounds
Solution Approach 1:
The system introduces asymmetry in the round execution by using different numbers of normal and redundant rounds, and by randomly varying their sequences. This asymmetric design ensures that no two executions follow the same pattern, making it difficult for attackers to identify and manipulate specific vulnerable rounds while maintaining manageable control logic through randomized parameters.
Solution Approach 2:
The controller dynamically changes parameters such as the number of rounds, their sequence, and timing intervals based on operational context and security requirements. By varying these parameters randomly or adaptively, the system prevents attackers from predicting the execution pattern while keeping the control mechanism relatively simple through parameter randomization rather than complex control logic.
Data Source
AI summary
A method for tamper protection in cryptographic calculations is provided. A cryptographic calculation includes a plurality of normal rounds and a plurality of redundant rounds. The method includes obtaining a first variable x and a second variable y using a random number generator; dividing the normal rounds into a first normal section and a second normal section, and dividing the redundant rounds into a first redundant section and a second redundant section according to the first variable x and the second variable y; executing the first normal section and the first redundant section in sequence using a clock signal; in response to completion of the first redundant section and a first calculation result of the first normal section and a second calculation result of the first redundant section being the same, executing the second normal section and the second redundant section in sequence to complete the cryptographic calculation.