A Secure and Efficient White-Box Implementation of SM4.

Area of Science:

• Cryptography
• Computer Security
• Information Theory

Background:

• Differential Computation Analysis (DCA) attacks exploit memory traces to extract secret keys from white-box implementations.
• Existing countermeasures against DCA often compromise algorithmic efficiency.
• Secure and efficient white-box implementations remain a significant challenge in cryptography.

Purpose of the Study:

• To develop a novel white-box implementation of the SM4 cipher resistant to Differential Computation Analysis (DCA).
• To enhance security against key extraction while minimizing the impact on algorithmic efficiency.
• To reduce the memory footprint compared to existing DCA-resistant schemes.

Main Methods:

• Implemented the Feistel cipher SM4 using table-lookup operations.
• Protected table inputs/outputs with random affine transformations and nonlinear encodings.
• Utilized fourth-order nonlinear encoding to balance efficiency and security.
• Employed a random sequence to shuffle lookup table access, decoupling memory data from intermediate cipher values.

Main Results:

• Experimental results demonstrate the failure of DCA to retrieve the secret key.
• Theoretical analysis confirms the scheme's resistance to existing algebraic attacks.
• The proposed design achieves a memory requirement of only 1.44 MB, significantly lower than comparable schemes.

Conclusions:

• The developed SM4 white-box design effectively prevents key extraction via DCA.
• The approach offers a strong balance between cryptographic security and algorithmic efficiency.
• This scheme provides a memory-efficient solution for secure white-box implementations.