Adaptive Scan Chain Prevents Differential Cryptanalysis in AES Circuits
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Solution Overview
Problem
Differential cryptanalysis attacks pose a significant threat to the security of AES circuits, as attackers can exploit the scan chain to recover encryption keys, compromising the security of encryption chips and leading to leakage of personal privacy information.
Innovation Solution
An adaptive scan chain system is introduced, controlled by a plaintext analysis module and a control module, which changes the structure of the scan chain based on the analysis of input plaintexts, routing plaintexts through either a common or complex scan chain to confuse attackers and prevent key recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DFT technology is introduced to detect manufacturing failures, then testing capability is improved, but chip security deteriorates due to scan chain exploitation
Solution Approach 1:
The scan chain structure is transformed from static to dynamic by introducing a control module that adjusts the scan chain configuration based on operational mode. In normal mode, the scan chain operates in encryption mode with cryptographic operations; in test mode, it switches to test mode with manufacturing defect detection. This dynamic reconfiguration prevents attackers from exploiting a fixed scan chain structure while maintaining both testing capability and security.
Solution Approach 2:
The patent changes the operational parameters of the scan chain based on mode selection. The control module receives mode selection signals and adjusts the scan chain's operational state accordingly - enabling cryptographic parameter sets for encryption mode and test parameter sets for manufacturing detection mode. This parameter switching prevents differential cryptanalysis attacks by ensuring that test mode operations do not expose unencrypted intermediate values that would exist in a static scan chain configuration.
2Object-affected harmful factors
If scan chain structure is changed to prevent attacks, then chip security is improved, but device complexity increases
Solution Approach 1:
The scan chain is designed with multi-functionality to perform both manufacturing defect detection and cryptographic operations. The control module enables a single scan chain structure to serve dual purposes: in test mode, it detects manufacturing failures through traditional DFT operations; in normal mode, it performs encryption/decryption operations. This universal design eliminates the need for separate test and security circuits, reducing overall device complexity while maintaining enhanced security against differential cryptanalysis attacks.
Solution Approach 2:
The control module acts as an intermediary that manages the scan chain's operational state based on mode selection signals. It receives external mode selection inputs and internally configures the scan chain accordingly, shielding the complexity of dual-mode operations from both users and potential attackers. The control module simplifies the interface while managing the complex internal reconfiguration, making the system easier to use without exposing the underlying complexity that enables security.
Data Source
AI summary
A method for preventing a differential cryptanalysis attack is provided. The method is implemented by an adaptive scan chain, a control module, and a plaintext analysis module. The plaintext analysis module controls the adaptive scan chain, so that two plaintexts differing in the last bit of only one byte are input through scan chains with different structures. Consequently, the two input plaintexts for which differential cryptanalysis attack technology originally can be used to crack the key are unable to generate outputs that can be used by the differential cryptanalysis attack technology.