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Questions tagged [private-set-intersection]

In a private set intersection (PSI) protocol two parties jointly compute the intersection of their private input sets.

In a private set intersection (PSI) protocol a client and a server jointly compute the intersection of their private input sets in a manner that at the end the client learns the intersection and the server learns nothing (one-way PSI) or both learn the intersection (mutual PSI).

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2-party private set intersection

Are there dedicated protocols to achieve a private set intersection where one of the set is of small constant size $c$ and the other one of size $n$? What are the resource complexities of this kind of protocol, in terms of communication and…
Dingo13
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True/False if a user is a customer without revealing the actual customer

I have a user A and a third party company B. I want to check if A is a customer of B. B cannot reveal any information about their customer list to me. If A is a customer of B, I do not want B to know which customer they are. They should only know…
Toby
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Private set intersection, using a semi-trusted server

Alice has a set $S$ of words. Bob has a set $T$ of words. They want to compute the intersection $S \cap T$ of their words, with the help of a semi-trusted third party Trent. Trent runs a central server. The server is normally well-intentioned…
D.W.
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Socialist Millionaires variant, where only one party learns $x=y$?

In the Socialist Millionaires protocol, Alice selcts some $x$ and Bob selects some $y$, and both parties learn whether or not $x=y$ without learning the other party's selected value. However, on a successful match, both parties do learn the other…
apsillers
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Malicious Model and Arbitrary selecting inputs on MPC and PSI

Imagine the following setting: a party considers a secret sharing or multiparty protocol that is secure against semi-honest adversaries. The adversary selectively chooses the inputs such that it could learn the inputs of its counterparts from what…
DaWNFoRCe
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Multiparty dataset intersection count

Typically, Private Set Intersection (PSI) protocols let you learn the subset of items on each party's dataset that are in the intersection. The problem in this case is a relaxation of these kind of constructions. I would like to learn only the…
DaWNFoRCe
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What are the advantages of mutual private set intersection methods over finding the intersection of hashed lists?

I can understand the usefulness of one-way private set intersection methods. Where Alice and Bob both have listed but only Alice learns the intersection of those lists while Bob learns nothing. I don't understand the usefulness of two-way private…
Curious Curt
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Can we convert a pseudorandom function (PRF) to an Oblivious PRF (OPRF) through an Oblivious Transfer (OT) protocol?

I'm a software engineer, so I generally think in building blocks. And I'm not so familiar with the Math notation in Crytography, so I'll stick with function calls and function blueprints (which I assume would be as intuitive). Lately I've been…
zetaprime
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Find out a set of values without sharing my own

I have the following problem which i am trying to find a reasonable protocol to solve it. This is a simplified version of the problem. Alice has a set of values $\{a_1,a_2,...,a_n\}$. Bob has a set of values $\{b_1,b_2,...,b_n\}$. Alice wants to…
Black_b_r
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Practical implementations of Private Set Membership

Problem Statement Imagine you have a set (no duplicate elements) e.g. S1 = {'a', 'b', 'c'}. You wish to share a private (and ideally both small in size and integrity protected) representation of this set with another party (who could have pre-shared…
JoeKir
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How to find common answers without revealing differences?

Say Bob and Alice are trying to figure out the fruits they like, but don't want to reveal the fruits they dislike. How could they compare their list of liked fruits and reveal only the common set to the other person? In this scenario, each party…
saucewaffle
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Correctness of signle-point Oblivious PRF

In the paper Private Set Intersection in the Internet Setting From Lightweight Oblivious PRF, Chase et al. shows that a PSI scheme can be achieved by using an oblivious PRF (OPRF). They summarized a single point OPRF protocol between a sender $S$…
vxek
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Design a OT-based Private Set Intersection protocol to obtain $A \cap B \cap C$?

This is a tutorial question for a Foundations of Privacy computer science course, I'm unsure on how to tackle it because we haven't talked much about these particular topics in class. (a) Assume Alice, Bob and Carlo respectively have the data set…
Kiyi1994
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communication efficient private lookup

I have a scenario where a client has a private set and the server has a large public set, we would like an estimate of the intersection size or more specifically the percent of the private set covered by the public set. However we do not want to…
Meir Maor
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ElGamal in private set intersection: how to handle negative numbers?

I am trying to implement the Efficient Robust Private Set Intersection using Additive ElGamal. For this, from the client side, my inputs are $C = \{1, 2\}$. So, the polynomial is $(x-1)(x-2)$ which is $x^2-3x+2$. The next step is to encrypt the…
Sunil
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