Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Fundamental Price of Secure Aggregation in Differentially Private
  Federated Learning   We consider the problem of training a $d$ dimensional model with distributed
differential privacy (DP) where secure aggregation (SecAgg) is used to ensure
that the server only sees the noisy sum of $n$ model updates in every training
round. Taking into account the constraints imposed by SecAgg, we characterize
the fundamental communication cost required to obtain the best accuracy
achievable under $\varepsilon$ central DP (i.e. under a fully trusted server
and no communication constraints). Our results show that $\tilde{O}\left(
\min(n^2\varepsilon^2, d) \right)$ bits per client are both sufficient and
necessary, and this fundamental limit can be achieved by a linear scheme based
on sparse random projections. This provides a significant improvement relative
to state-of-the-art SecAgg distributed DP schemes which use
$\tilde{O}(d\log(d/\varepsilon^2))$ bits per client.
  Empirically, we evaluate our proposed scheme on real-world federated learning
tasks. We find that our theoretical analysis is well matched in practice. In
particular, we show that we can reduce the communication cost significantly to
under $1.2$ bits per parameter in realistic privacy settings without decreasing
test-time performance. Our work hence theoretically and empirically specifies
the fundamental price of using SecAgg.

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The categories of this paper are: atom-ph
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The categories of this paper are: q-alg
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The categories of this paper are: math
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The categories of this paper are: physics
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The categories of this paper are: chao-dyn
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The categories of this paper are: cond-mat
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The categories of this paper are: patt-sol
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The categories of this paper are: chem-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: funct-an
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The categories of this paper are: ao-sci
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The categories of this paper are: eess
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The categories of this paper are: nlin
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The categories of this paper are: nucl-ex