Data Protecting Apparatus Using Galois Field Mixing for Stream Cipher Security
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Solution Overview
Problem
Stream-ciphered data in secure storage systems is vulnerable to cryptographic attacks, particularly those based on bit positions, which can compromise the security of the interface between a host and a memory device.
Innovation Solution
A cryptographic mixing operation using Galois Field (GF) multipliers is applied to plaintext data, mapping it into mixed bits that are then stream-ciphered, with the mixing key being the GF multiplicative inverse of a corresponding key on the remote apparatus, ensuring secure communication over the interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stream ciphering is applied to protect data on the communication link, then security against unauthorized access is improved, but vulnerability to bit position-based cryptographic attacks increases
Solution Approach 1:
The patent applies a mixing operation before stream ciphering to preprocess the plaintext data. This preliminary action transforms the data into a form that is resistant to bit position-based cryptographic attacks, while the subsequent stream ciphering provides protection against unauthorized access. The mixing operation uses Galois Field multipliers with mixing keys that are GF multiplicative inverses of corresponding keys on the remote apparatus.
Solution Approach 2:
The patent introduces a mixing operation as an intermediary step between the plaintext and stream ciphering. This intermediary transformation using Galois Field multipliers and mixing keys creates a cryptographic mapping that disrupts bit position patterns, making the data resistant to bit position-based attacks while maintaining compatibility with subsequent stream ciphering operations.
2Reliability
If a mixing operation using Galois Field multipliers is applied to plaintext data, then resistance to bit position-based cryptographic attacks is improved, but device complexity increases
Solution Approach 1:
The patent divides the mixing operation into multiple mixing stages, each containing multiple Galois Field multipliers. The input bits are split among the GF multipliers of the first mixing stage, and results from the last mixing stage are combined to produce output bits. This segmentation allows the complex mixing operation to be implemented as a series of simpler, parallel operations.
Solution Approach 2:
The patent uses GF multiplicative inverses as mixing keys, where the mixing key on one apparatus is the GF multiplicative inverse of the corresponding mixing key on the remote apparatus. This parameter relationship simplifies the implementation, as the inverse relationship provides a systematic way to generate corresponding keys without requiring complex key management.
Data Source
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AI summary
A data protecting apparatus and a method thereof are provided. The apparatus includes an interface and logic circuitry. The interface is configured to communicate over a communication link. The logic circuitry is configured to convert between a first stream of plaintext bits and a second stream of ciphered bits that are exchanged over the communication link, by applying a cascade of a stream ciphering operation and a mixing operation that cryptographically maps input bits to output bits.