A Hassle-free Algorithm for Private Learning in Practice: Don't Use Tree Aggregation, Use BLTs
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Abstract (arXiv)
The state-of-the-art for training on-device language models for mobile keyboard applications combines federated learning (FL) with differential privacy (DP) via the DP-Follow-the-Regularized-Leader (DP-FTRL) algorithm. Two variants of DP-FTRL are used in practice, tree aggregation and matrix factorization. However, tree aggregation suffers from significantly suboptimal privacy/utility tradeoffs, while matrix mechanisms require expensive optimization parameterized by hard-to-estimate-in-advance constants, and high runtime memory costs. This paper extends the recently introduced Buffered Linear Toeplitz (BLT) mechanism to multi-participation scenarios. Our BLT-DP-FTRL maintains the ease-of-use advantages of tree aggregation, while essentially matching matrix factorization in terms of utility and privacy. We evaluate BLT-DP-FTRL on the StackOverflow dataset, serving as a re-producible simulation benchmark, and across four on-device language model tasks in a production FL system. Our empirical results highlight the advantages of the BLT mechanism and elevate the practicality and effectiveness of DP in real-world scenarios.
Key facts. Cited by 9 papers in the map (data through 7 Oct 2026). Builds on 26 of its 37 references that are in the map. First posted on arXiv 16 Aug 2024.
Builds on
26 of 37 references.
References · 26
- 2016Communication-Efficient Learning of Deep Networks from Decentralized Datacited by 7,592
- 2019Advances and Open Problems in Federated Learningcited by 3,021
- 2016Deep Learning with Differential Privacycited by 2,682
- 2020mT5: A massively multilingual pre-trained text-to-text transformercited by 1,813
- 2019Towards Federated Learning at Scale: System Designcited by 826
- 2018Federated Learning for Mobile Keyboard Predictioncited by 565
- 2016Concentrated Differential Privacy: Simplifications, Extensions, and Lower Boundscited by 339
- 2021A Field Guide to Federated Optimizationcited by 312
- 2021Practical and Private (Deep) Learning without Sampling or Shufflingcited by 169
- 2021Papaya: Practical, Private, and Scalable Federated Learningcited by 89
- 2023Federated Learning of Gboard Language Models with Differential Privacycited by 64
- 2022Improved Differential Privacy for SGD via Optimal Private Linear Operators on Adaptive Streamscited by 59
14 more
- 2022Connect the Dots: Tighter Discrete Approximations of Privacy Loss Distributionscited by 50
- 2023(Amplified) Banded Matrix Factorization: A unified approach to private trainingcited by 49
- 2022Multi-Epoch Matrix Factorization Mechanisms for Private Machine Learningcited by 48
- 2023Can Public Large Language Models Help Private Cross-device Federated Learning?cited by 30
- 2024Fine-Tuning Large Language Models with User-Level Differential Privacycited by 28
- 2022Learning to Generate Image Embeddings with User-level Differential Privacycited by 23
- 2024Mind the Privacy Unit! User-Level Differential Privacy for Language Model Fine-Tuningcited by 21
- 2024Prompt Public Large Language Models to Synthesize Data for Private On-device Applicationscited by 17
- 2024Efficient and Near-Optimal Noise Generation for Streaming Differential Privacycited by 17
- 2023A Smooth Binary Mechanism for Efficient Private Continual Observationcited by 12
- 2024Banded Square Root Matrix Factorization for Differentially Private Model Trainingcited by 12
- 2024Scaling up the Banded Matrix Factorization Mechanism for Differentially Private MLcited by 12
- 2023Private Federated Learning in Gboardcited by 5
- 2024Confidential Federated Computationscited by 4
Built on by
Citing papers per year: 2024: 2; 2025: 5; 2026: 2.
9 papers.
- 2024Federated Learning in Practice: Reflections and Projectionscited by 15
- 2025Back to Square Roots: An Optimal Bound on the Matrix Factorization Error for Multi-Epoch Differentially Private SGDcited by 7
- 2025An Inversion Theorem for Buffered Linear Toeplitz (BLT) Matrices and Applications to Streaming Differential Privacycited by 3
- 2025Private Continual Counting of Unbounded Streamscited by 2
- 2024Debiasing Federated Learning with Correlated Client Participationcited by 1
- 2025Cocoon: A System Architecture for Differentially Private Training with Correlated Noisescited by 1
- 2026DP-λCGD: Efficient Noise Correlation for Differentially Private Model Trainingcited by 1
- 2025Securing Private Federated Learning in a Malicious Setting: A Scalable TEE-Based Approach with Client Auditingcited by 0
- 2026Beyond Square Roots: A Memory-Efficient Explicit Factorization for Multi-Epoch Private Learningcited by 0
- 2026Beyond Square Roots: A Memory-Efficient Explicit Factorization for Multi-Epoch Private Learning18 May 2026
- 2026DP-λCGD: Efficient Noise Correlation for Differentially Private Model Training29 Jan 2026
- 2025Cocoon: A System Architecture for Differentially Private Training with Correlated Noises8 Oct 2025
- 2025Securing Private Federated Learning in a Malicious Setting: A Scalable TEE-Based Approach with Client Auditing10 Sep 2025
- 2025Private Continual Counting of Unbounded Streams17 Jun 2025
- 2025Back to Square Roots: An Optimal Bound on the Matrix Factorization Error for Multi-Epoch Differentially Private SGD17 May 2025
- 2025An Inversion Theorem for Buffered Linear Toeplitz (BLT) Matrices and Applications to Streaming Differential Privacy30 Apr 2025
- 2024Federated Learning in Practice: Reflections and Projections11 Oct 2024
- 2024Debiasing Federated Learning with Correlated Client Participation2 Oct 2024