Preserving Data Privacy in Learning Causal Structure with Fully Homomorphic Encryption
Pith reviewed 2026-06-28 05:20 UTC · model grok-4.3
The pith
Causal structure learning can run on fully encrypted data with accuracy matching plaintext versions by approximating division and logarithm operations.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
All steps of causal structure learning can be executed directly on ciphertexts by replacing unsupported operations with Newton-Raphson reciprocal and Taylor expansions, together with circuit simplification and SIMD batching, so that the recovered structures match the plaintext versions in consistency and accuracy.
What carries the argument
Newton-Raphson reciprocal approximation for division and Taylor expansion for logarithm, applied inside a circuit-simplified, SIMD-batched FHE workflow that keeps data encrypted throughout.
If this is right
- Causal discovery becomes possible on distributed encrypted data without any party decrypting intermediates.
- The same approximation pipeline supports differential privacy as an alternative protection layer.
- Learning completes in tens of minutes even under full FHE protection.
- High consistency with plaintext results holds across the datasets examined.
Where Pith is reading between the lines
- Organizations could pool encrypted records for joint causal analysis without exposing raw values.
- The method might scale to larger graphs if the approximation error stays bounded as node count grows.
- Applying the same approximations to other graph-learning tasks that rely on division and logs could be tested directly.
Load-bearing premise
The numerical approximations for division and logarithm keep enough accuracy that downstream causal discovery still recovers the correct structure.
What would settle it
A dataset where the plaintext algorithm recovers the true causal graph but the FHE version with approximations recovers a different graph would show the accuracy claim fails.
Figures
read the original abstract
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.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper proposes an FHE-based approach for privacy-preserving causal structure learning. It tackles FHE limitations on division and logarithm via Newton-Raphson reciprocal approximation and Taylor expansions, plus circuit simplification and SIMD batching for efficiency. The method is claimed to extend to differential privacy, and empirical results assert high consistency with plaintext causal discovery on tested datasets, with runtimes in tens of minutes.
Significance. If the numerical approximations preserve sufficient fidelity for downstream causal algorithms, the work would be a practical contribution to secure distributed causal discovery. The engineering focus on circuit simplification, batching, and portability to DP is a strength, as is the direct empirical test of the core assumption that the approximations do not degrade structure recovery.
major comments (2)
- [Abstract / Experiments] Abstract and experimental results: the central claim that the method 'achieves high consistency and comparable causal structure with the plaintext version in the datasets tested' is load-bearing, yet the provided text supplies no datasets, sample sizes, metrics (e.g., SHD, precision/recall on edges), error bars, or ablation on approximation parameters. This prevents evaluation of whether the Newton-Raphson/Taylor approximations meet the weakest-assumption threshold.
- [Method (approximations subsection)] Approximation methods: the Newton-Raphson reciprocal and Taylor expansions for division and logarithm lack any reported error bounds, convergence analysis, or propagation study showing that the induced numerical error does not alter the output of the causal discovery procedure. Because the paper's correctness rests on these approximations preserving structure, a concrete sensitivity test (e.g., graph difference under varying iteration counts or polynomial degree) is required.
minor comments (1)
- [Implementation details] Notation for the batching and SIMD parameters could be clarified with an explicit table of ciphertext packing sizes and their effect on throughput.
Simulated Author's Rebuttal
We thank the referee for the constructive feedback. The comments highlight areas where the manuscript can be strengthened with additional experimental details and analysis. We will revise accordingly and address each point below.
read point-by-point responses
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Referee: [Abstract / Experiments] Abstract and experimental results: the central claim that the method 'achieves high consistency and comparable causal structure with the plaintext version in the datasets tested' is load-bearing, yet the provided text supplies no datasets, sample sizes, metrics (e.g., SHD, precision/recall on edges), error bars, or ablation on approximation parameters. This prevents evaluation of whether the Newton-Raphson/Taylor approximations meet the weakest-assumption threshold.
Authors: We agree the manuscript lacks these specifics in the abstract and experimental reporting. In revision we will expand the experiments section to list the exact datasets (standard benchmarks such as Asia and Sachs), sample sizes, quantitative metrics including SHD and edge precision/recall with error bars across runs, and ablations varying approximation parameters (iteration counts, polynomial degrees) to show that structure recovery remains comparable to plaintext. revision: yes
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Referee: [Method (approximations subsection)] Approximation methods: the Newton-Raphson reciprocal and Taylor expansions for division and logarithm lack any reported error bounds, convergence analysis, or propagation study showing that the induced numerical error does not alter the output of the causal discovery procedure. Because the paper's correctness rests on these approximations preserving structure, a concrete sensitivity test (e.g., graph difference under varying iteration counts or polynomial degree) is required.
Authors: The current text describes the approximations but omits explicit bounds and sensitivity results. We will add a dedicated analysis subsection reporting error bounds for the Newton-Raphson reciprocal and Taylor series, convergence behavior, and propagation through the causal algorithm. This will include sensitivity experiments measuring graph differences (SHD, edge changes) under different iteration counts and polynomial degrees to confirm the approximations preserve the recovered structure. revision: yes
Circularity Check
No significant circularity
full rationale
The paper presents an empirical method for causal structure learning under FHE, using circuit simplification, Newton-Raphson reciprocal, Taylor expansions for division/log, and SIMD batching. Its central claim is that the encrypted version achieves high consistency and comparable structure to the plaintext version on tested datasets. This is validated by direct external comparison rather than any internal derivation that reduces to fitted parameters, self-definitions, or self-citation chains. No load-bearing step equates a prediction to its own inputs by construction; the numerical fidelity of the approximations is treated as an empirical question tested outside the method itself.
Axiom & Free-Parameter Ledger
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