Split-and-Merge Cryptographic Operations Against DFA Attacks
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Solution Overview
Problem
Cryptographic functions are vulnerable to differential fault analysis (DFA) attacks, especially in white-box and grey-box attack models where attackers can manipulate side-channel information and gain control over the execution environment, compromising the security of digital content protection mechanisms.
Innovation Solution
Implementing a split-and-merge approach in cryptographic operations, such as AES and DES, using secret sharing and complementary weights to split and combine intermediate values, making it difficult for attackers to derive the cryptographic key through fault injection attacks by ensuring that changes in output values do not reveal the key.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cryptographic functions are implemented in white-box or grey-box environments, then accessibility and flexibility are improved, but security against DFA attacks deteriorates
Solution Approach 1:
The cryptographic computation is divided into multiple rounds with intermediate values being split into shares. Each share is processed separately through subsequent rounds, preventing attackers from obtaining complete intermediate values that would reveal key information through fault analysis.
Solution Approach 2:
Secret sharing acts as an intermediary mechanism between the cryptographic key and the computation process. The key is never directly used in a single form but is distributed across multiple shares that must be combined to reconstruct the key, adding a protective layer against DFA attacks.
2Reliability
If intermediate values are split using secret sharing, then security against DFA attacks is improved, but computational complexity increases
Solution Approach 1:
The cryptographic computation is divided into multiple rounds with intermediate values being split into shares. Each share is processed separately through subsequent rounds, preventing attackers from obtaining complete intermediate values that would reveal key information through fault analysis.
Solution Approach 2:
Multiple shared values are merged back together in the final round to produce the output. The merging process uses the same cryptographic operations as the splitting process, ensuring that the security properties are maintained while recovering the final result.
Data Source
AI summary
A device for performing a mapping an input message to an output message by a keyed cryptographic operation, wherein the keyed cryptographic operation includes a plurality of rounds. To protect against differential fault analysis attacks, the cryptographic operation is modified to apply a secret sharing approach to one of the rounds. Also, a portion of the computations are split into first and second shares, where the first share uses a first weight and the second share uses a second weight. The final operations are again merged into a single matrix multiplication. Cryptographic operations that have a substitution function and an affine transformation can be protected in this way.