Cryptography Circuit Masking Against DPA Attacks
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Solution Overview
Problem
Current cryptographic systems are vulnerable to attacks via auxiliary channels such as DPA and EMA, which exploit information leaks from the temporal behavior, energy consumption, or radiative behavior of cryptographic systems, despite existing protections like dissimulation and masking.
Innovation Solution
A cryptography circuit incorporating a second, independent key specific to each instance, used to mask and protect the functional key through XOR operation, generated by PUF or POK, ensuring confidentiality and resistance to high-order DPA attacks, with customizable implementation on FPGA circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If masking techniques are used to protect against auxiliary channel attacks, then security against DPA and EMA attacks is improved, but the system remains vulnerable to high-order attacks and implementation flaws
Solution Approach 1:
The cryptographic key is segmented into multiple components through masking, where the functional key kc is combined with a second key ki to create a masked key kc ⊕ ki. This segmentation ensures that even if one component is compromised through auxiliary channel attacks, the other components remain protected, thereby improving reliability while managing complexity through structured key management
Solution Approach 2:
A second key ki acts as an intermediary between the functional key kc and the auxiliary channels. This intermediary key, generated by PUF or POK, masks the functional key and protects it from direct observation through DPA or EMA attacks, while still allowing the cryptographic algorithm to function correctly when the masking is properly applied and removed in secure contexts
2Loss of information
If the functional key is masked by combining with a second key through XOR operation, then information leaks become incomprehensible and first-order attacks are prevented, but the system requires additional key management infrastructure
Solution Approach 1:
The second key ki serves as a mediator that transforms the functional key kc into a masked form kc ⊕ ki. This intermediary key obscures the information leakage by ensuring that any observed data through auxiliary channels represents the masked value rather than the functional key directly, making first-order correlation attacks ineffective while the key management infrastructure handles the generation and protection of ki
Solution Approach 2:
The system changes the parameter of the key representation by applying XOR masking with the second key ki. This parameter transformation ensures that the functional key kc is never observed in its original form during cryptographic operations, thereby preventing information leakage through auxiliary channels while maintaining the ability to perform cryptographic functions when the masking is properly managed
3Reliability
If a second key specific to each circuit instance is used for protection, then resistance to brute-force attacks is increased, but the circuit requires personalization and unique key generation
Solution Approach 1:
The circuit generates its own unique second key ki through PUF (Physically Unclonable Functions) or POK (Physically Obfuscated Keys) that are inherent to each circuit instance. This self-service approach to key generation eliminates the need for external key distribution infrastructure and ensures that each circuit has a unique masking key, thereby increasing resistance to brute-force attacks while simplifying the manufacturing process through automated key generation
Solution Approach 2:
Each circuit instance has a locally unique second key ki that is specific to that particular circuit. This local quality ensures that even if one circuit is compromised, other circuits remain protected with their own unique keys, thereby increasing overall system reliability and resistance to brute-force attacks while the personalization process is handled through circuit-specific physical characteristics
Data Source
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AI summary
The invention relates to a cryptography circuit that is particularly protected against attacks based on the observation of information leaks. The cryptography circuit (21) includes a functional key k c for running an cryptography algorithm. It comprises a second unique key k i that is particular to the circuit for protecting y masking the functional and confidential key k c or a confidential implementation of the algorithm.