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Distributed learning allows a group of independent data owners to collaboratively learn a model over their data sets without exposing their private data. We present a distributed learning approach that combines differential privacy with secure multi-party computation. We explore two popular methods of differential privacy, output perturbation and gradient perturbation, and advance the state-of-the-art for both methods in the distributed learning setting. In our output perturbation method, the parties combine local models within a secure computation and then add the required differential privacy noise before revealing the model. In our gradient perturbation method, the data owners collaboratively train a global model via an iterative learning algorithm. At each iteration, the parties aggregate their local gradients within a secure computation, adding sufficient noise to ensure privacy before the gradient updates are revealed. For both methods, we show that the noise can be reduced in the multi-party setting by adding the noise inside the secure computation after aggregation, asymptotically improving upon the best previous results. Experiments on real world data sets demonstrate that our methods provide substantial utility gains for typical privacy requirements.
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Combatting The Challenges of Local Privacy for Distributional Semantics with Compression
Traditional methods for adding locally private noise to bag-of-words features overwhelm the true signal in the text data, removing the properties of sparsity and non-negativity often relied upon by distributional semantic models. We argue the formulation of limited-precision local privacy, which guarantees privacy between documents of less than a user-specified maximum distance, is a more appropriate framework for bag-of-words features. To reduce the number of features to which we must add random noise, we also compress word features before adding noise, then decompress those features before model inference. We test randomized methods of aggregation as well as methods informed by distributional properties of words. Applying LDA and LSA to synthetic and real data, we show that these approaches produce distributional models closer to those in the original data.
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- Award ID(s):
- 1652536
- PAR ID:
- 10162559
- Date Published:
- Journal Name:
- PriML workshop at NeurIPS
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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