Split Masked Tables for Cryptographic Process Security
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Solution Overview
Problem
Existing cryptographic systems face challenges in resisting power analysis attacks, such as differential power analysis (DPA), which compromise the security of cryptographic operations by monitoring power consumption, and require additional resources for countermeasures like table regeneration or masking, which are not always feasible.
Innovation Solution
The implementation of split masked tables generated using an original substitution table and random values, where each entry is masked with multiple random values to create multiple split masked tables, reducing the overhead and enhancing resistance to DPA attacks by making it difficult to obtain viable samples for attacks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequent regeneration of tables using different random output masks is used, then resistance to power analysis attacks is improved, but additional memory, power and processor resources are required
Solution Approach 1:
The patent divides the substitution table into multiple smaller tables (e.g., four 32-bit tables instead of one 128-bit table). Each small table is then masked with random values during cryptographic operations. This segmentation allows the system to achieve table regeneration and masking effects without requiring a single large table to be completely regenerated, thereby reducing memory bandwidth requirements and processor overhead while maintaining security against power analysis attacks.
2Reliability
If fixed value masking with multiple masks is used, then resistance to power analysis attacks is improved, but additional memory and processor resources are required
Solution Approach 1:
The patent employs dynamic masking where random values are generated and applied to mask table entries during cryptographic operations. The masking values are not fixed but are dynamically generated based on the operational context. This dynamic approach allows the system to use fewer pre-computed masks while still achieving security effects, reducing the memory footprint for storing multiple fixed masks and the processor resources needed to manage them.
3Reliability
If table regeneration or masking countermeasures are implemented, then security against DPA attacks is improved, but latency overheads increase
Solution Approach 1:
The patent pre-divides the substitution table into multiple smaller tables before the cryptographic operation begins. This preliminary segmentation allows that during actual cryptographic processing, the system only needs to access and mask small portions of data rather than regenerating entire tables. The masking operation is performed on the small table entries during the cryptographic algorithm execution, minimizing latency overhead while maintaining security.
Data Source
AI summary
For a defined cryptographic process including an original substitution table, split masked substitution tables are provided to resist cryptographic attacks. The split masked substitution tables are defined with reference to a set of random value data words and a mask value. An entry in the split masked substitution tables is defined by selecting bits from the corresponding entry in the original masked substitution table, as masked by the corresponding one of the set of random value data words and by selecting bits from the corresponding one of the set of random value data words as masked by the mask value. The split masked substitution tables are usable in a modified cryptographic process based on the defined cryptographic process to permit a masked output to be generated. The split masked substitution tables are refreshed by each entry in the tables being refreshed upon access during execution of the modified cryptographic process.