Recognition: unknown
DisAgg: Distributed Aggregators for Efficient Secure Aggregation in Federated Learning
Pith reviewed 2026-05-14 17:46 UTC · model grok-4.3
The pith
DisAgg distributes aggregation to a small client committee via secret sharing to cut secure FL computation while preserving privacy.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
DisAgg has clients secret-share their update vectors to a committee of Aggregators, which locally compute partial sums on the shares and return only the aggregated shares to the server for reconstruction, removing local masking and public-key operations to deliver a 4.6x speedup over OPA for 100k clients with 100k-dimensional vectors.
What carries the argument
A small committee of clients acting as Aggregators that receive secret shares, perform local partial summation, and forward only the aggregated shares to the server.
If this is right
- Supports scaling federated learning to higher client counts and larger model dimensions without proportional growth in client-side computation.
- Lowers total latency by replacing per-client cryptographic masking with lighter secret-sharing operations.
- Keeps the single server interaction per round while adding resilience through the aggregator committee structure.
- Reduces the computational burden on resource-constrained devices such as 5G clients.
Where Pith is reading between the lines
- The committee approach may extend to other distributed aggregation tasks where a central party needs sums without seeing individuals.
- Dynamic selection of the aggregator committee based on client uptime or compute capacity could further improve reliability in practice.
- The reported trade-off between communication and computation could be tested by varying committee size in large-scale simulations.
Load-bearing premise
The protocol assumes secret sharing to the aggregator committee delivers privacy without extra overhead and that the fraction of colluding clients stays below the threshold that would allow reconstruction of individual updates.
What would settle it
Measure whether the full protocol with 100k clients each sending 100k-dimensional vectors runs in 4.6 times less time than OPA while no client update can be recovered by the server or by any allowed number of colluding clients.
Figures
read the original abstract
Federated learning enables collaborative model training across distributed clients, yet vanilla FL exposes client updates to the central server. Secure-aggregation schemes protect privacy against an honest-but-curious server, but existing approaches often suffer from many communication rounds, heavy public-key operations, or difficulty handling client dropouts. Recent methods like One-Shot Private Aggregation (OPA) cut rounds to a single server interaction per FL iteration, yet they impose substantial cryptographic and computational overhead on both server and clients. We propose a new protocol called DisAgg that leverages a small committee of clients called Aggregators to perform the aggregation itself: each client secret-shares its update vector to Aggregators, which locally compute partial sums and return only aggregated shares for server-side reconstruction. This design eliminates local masking and expensive homomorphic encryption, reducing endpoint computation while preserving privacy against a curious server and a limited fraction of colluding clients. By leveraging optimal trade-offs between communication and computation costs, DisAgg processes 100k-dimensional update vectors from 100k 5G clients with a 4.6x speedup compared to OPA, the previous best protocol.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper presents DisAgg, a secure aggregation protocol for federated learning in which clients secret-share their update vectors to a small committee of aggregator clients. The aggregators compute local partial sums and return only aggregated shares to the server for reconstruction. This eliminates per-client masking and homomorphic encryption, yielding a claimed 4.6x speedup over OPA for 100k-dimensional vectors from 100k clients while preserving privacy against a curious server and a bounded fraction of colluding clients.
Significance. If the speedup and privacy properties are rigorously validated, the committee-based secret-sharing design would constitute a meaningful efficiency advance for large-scale secure FL. It trades modest additional communication for substantially lower per-client and server computation, which could improve practicality in settings such as 5G networks where prior one-shot protocols incur prohibitive cryptographic costs.
major comments (2)
- [Security Analysis] Security Analysis section: the privacy claim against a curious server and limited colluding clients is asserted via standard secret-sharing properties but lacks a formal game-based proof or reduction; this is load-bearing for the central privacy guarantee.
- [Performance Evaluation] Performance Evaluation section (results for 100k clients / 100k dimensions): the 4.6x speedup versus OPA is stated without detailed experimental methodology, baseline implementations, communication-volume measurements, or statistical analysis, preventing verification of the performance claim.
minor comments (2)
- [Abstract] Abstract: the phrase 'optimal trade-offs' is used without specifying the concrete committee size, threshold, or cost model that realizes the claimed speedup.
- [Notation] Notation and figures: the notation for secret shares and partial sums would benefit from an explicit small-scale example or diagram to aid readability.
Simulated Author's Rebuttal
We thank the referee for the constructive feedback. The comments highlight areas where additional rigor and detail will strengthen the manuscript. We address each major comment below and plan to incorporate the suggested improvements in the revised version.
read point-by-point responses
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Referee: [Security Analysis] Security Analysis section: the privacy claim against a curious server and limited colluding clients is asserted via standard secret-sharing properties but lacks a formal game-based proof or reduction; this is load-bearing for the central privacy guarantee.
Authors: We agree that a formal game-based proof would make the privacy argument more rigorous. The current analysis relies on the standard threshold security of Shamir secret sharing against a bounded number of colluding clients and an honest-but-curious server. In the revision we will add an explicit security game in the Security Analysis section together with a reduction showing that any successful attack on DisAgg implies an attack on the underlying secret-sharing scheme. We will also state the precise collusion threshold and corruption model more formally. revision: yes
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Referee: [Performance Evaluation] Performance Evaluation section (results for 100k clients / 100k dimensions): the 4.6x speedup versus OPA is stated without detailed experimental methodology, baseline implementations, communication-volume measurements, or statistical analysis, preventing verification of the performance claim.
Authors: We acknowledge that the experimental section currently lacks sufficient detail for independent verification. In the revised manuscript we will expand the Performance Evaluation section to include: (i) a complete description of the simulation environment and hardware, (ii) implementation details and source references for both DisAgg and the OPA baseline, (iii) measured communication volumes broken down by client-to-aggregator, aggregator-to-server, and reconstruction phases, and (iv) statistical results from multiple runs with means, standard deviations, and confidence intervals. revision: yes
Circularity Check
No significant circularity in derivation chain
full rationale
The protocol builds on standard secret-sharing and committee aggregation primitives described in the abstract. No equations, fitted parameters, or self-citations are shown that reduce the speedup or privacy claims to definitions or inputs by construction. The 4.6x speedup is presented as an empirical outcome from concrete choices (committee size, threshold, dimension) rather than a tautological renaming or self-referential prediction. The derivation remains self-contained against external benchmarks.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption Security model assumes an honest-but-curious server and that only a limited fraction of clients collude.
invented entities (1)
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Aggregators committee
no independent evidence
Reference graph
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