Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Relax the Non-Collusion Assumption for Multi-Server PIR   For distributed protocols involving many servers, assuming that they do not
collude with each other makes some secrecy problems solvable and reduces
overheads and computational hardness assumptions in others. While the
non-collusion assumption is pervasive among privacy-preserving systems, it
remains highly susceptible to covert, undetectable collusion among computing
parties. This work stems from an observation that if the number of available
computing parties is much higher than the number of parties required to perform
a secure computation, collusion attempts could be deterred.
  We focus on the standard problem of multi-server private information
retrieval (PIR) that inherently assumes that servers do not collude. For PIR
application scenarios, such as those for blockchain light clients, where the
available servers are plentiful, a single server's deviating action is not
tremendously beneficial to itself. We can make deviations undesired through
small amounts of rewards and penalties, thus {\em raising the bar} for
collusion significantly. For any given multi-server 1-private PIR (i.e., the
base PIR scheme is constructed assuming no pairwise collusion), we provide a
collusion mitigation mechanism. We first define a two-stage sequential game
that captures how rational servers interact with each other during collusion,
then determine the payment rules such that the game realizes the unique
sequential equilibrium: a non-collusion outcome. We also offer privacy
protection for an extended period after the query executions, and guarantee
user compensation in case of a reported privacy breach. Overall, we conjecture
that the incentive structure for collusion mitigation to be functional towards
relaxing the strong non-collusion assumptions across a variety of multi-party
computation tasks.

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The categories of this paper are: hep-ph
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The categories of this paper are: q-bio
30
The categories of this paper are: q-alg
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The categories of this paper are: quant-ph
6
The categories of this paper are: astro-ph
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-th
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The categories of this paper are: dg-ga
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The categories of this paper are: atom-ph
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The categories of this paper are: math
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The categories of this paper are: physics
33
The categories of this paper are: plasm-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: econ