做分布式数据挖掘或医疗、金融等隐私敏感领域因果分析的团队，终于有了一个可落地的加密方案——FHE 的算力瓶颈被巧妙绕过，建议直接看技术细节。
本文提出一种基于全同态加密（FHE）的因果结构学习方法，在数据传输和计算过程中全程保持加密状态，解决分布式场景下的隐私泄露问题。针对FHE计算成本高、不支持除法和对数运算的挑战，作者设计了电路简化、牛顿-拉夫森倒数近似和泰勒展开等创新技术，并利用SIMD批处理加速。该方法还能扩展支持差分隐私，实验表明在测试数据集上结果与明文版本高度一致，且能在数十分钟内完成学习。
Preserving Data Privacy in Learning Causal Structure with Fully Homomorphic Encryption
Preserving data privacy is an important topic in structural data management and data mining. However, the issue of privacy leakage in distributed causal structure learning is a persistent challenge, especially in cases where data transmission and computation are required. In this paper, we propose a method based on fully homomorphic encryption (FHE) that performs calculations on ciphertexts, keeping data encrypted in transition and computation. Nevertheless, adopting FHE to causal structure learning is challenging due to the high computation cost and limited support on division as well as logarithm operations in FHE. To tackle this challenge, we propose a series of novel techniques including (i) circuit simplification for better efficiency, (ii) approximation of division and logarithm through Newton-Raphson Reciprocal and Taylor expansion, and (iii) a batching technique with SIMD-acceleration to enhance the whole learning process. Additionally, our method can be easily extended beyond FHE by demonstration of its portability to support differential privacy. Empirical results show that our method achieves high consistency and comparable causal structure with the plaintext version in the datasets tested. Last, our method is efficient and practical to complete learning causal structures in tens of minutes even under the privacy protection of FHE.