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SoK: FHE-Friendly Symmetric Ciphers and Transciphering

Authors:
Chao Niu
Benqiang Wei
Zhicong Huang
Zhaomin Yang
Cheng Hong
Meiqin Wang
Tao Wei
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DOI: 10.46586/tches.v2025.i3.583-613
URL: https://tches.iacr.org/index.php/TCHES/article/view/12228
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Abstract: Fully Homomorphic Encryption (FHE) enables computation on encrypted data without decryption, demonstrating significant potential for privacy-preserving applications. However, FHE faces several challenges, one of which is the significant plaintext-to-ciphertext expansion ratio, resulting in high communication overhead between client and server. The transciphering technique can effectively address this problem by first encrypting data with a space-efficient symmetric cipher, then converting symmetric ciphertext to FHE ciphertext without decryption.Numerous FHE-friendly symmetric ciphers and transciphering methods have been developed by researchers, each with unique advantages and limitations. These often require extensive knowledge of both symmetric cryptography and FHE to fully grasp, making comparison and selection among these schemes challenging. To address this, we conduct a comprehensive survey of over 20 FHE-friendly symmetric ciphers and transciphering methods, evaluating them based on criteria such as security level, efficiency, and compatibility. We have designed and executed experiments to benchmark the performance of the feasible combinations of symmetric ciphers and transciphering methods across various application scenarios. Our findings offer insights into achieving efficient transciphering tailored to different task contexts. Additionally, we make our example code available open-source, leveraging state-of-the-art FHE implementations.
BibTeX
@article{tches-2025-35790,
  title={SoK: FHE-Friendly Symmetric Ciphers and Transciphering},
  journal={IACR Transactions on Cryptographic Hardware and Embedded Systems},
  publisher={Ruhr-Universität Bochum},
  volume={2025},
  pages={583-613},
  url={https://tches.iacr.org/index.php/TCHES/article/view/12228},
  doi={10.46586/tches.v2025.i3.583-613},
  author={Chao Niu and Benqiang Wei and Zhicong Huang and Zhaomin Yang and Cheng Hong and Meiqin Wang and Tao Wei},
  year=2025
}