Questions tagged [multiparty-computation]

Multi-party computation (MPC) allows a set of parties, each with a private input, to securely and jointly perform any computation over their inputs.

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Secure communication over insecure channel is based on the assumption of secure channel?

Consider a scenario:data owners $C$ sends a $l$ bits value $x$ to parties $P_0$ and $P_1$ via additively secret sharing scheme, for example, $C$ randomly selects $r \in_R \{0, 1\}^l$, and sends $r$ to ...
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Is there a winning strategy based on this coin-flipping protocol?

Given the coin flipping protocol: A chooses $a \in_R \{0,1\}$ and computes $commit(a,r)$. She sends $commit(a,r)$ to B. B chooses $b \in_R \{0,1\}$ and sends $b$ to A. A sends $open(a,r)$ and B ...
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Secretly compute multiplication of two numbers owned by two people

For example, Alice and Bob have two numbers $a$ and $b$, respectively. They want to calculate the multiplication $a\cdot b$ without Alice knowing $b$ or Bob knowing $a$ and send this multiplication $a\...
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Simulation based proof for Beaver's multiplication protocol

Setup Recently, I became interested in simulation based proofs in the context of secure two party computation. I read some book chapters (from Secure MPC and Secret Sharing and Foundations on ...
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A single array access with multiplexers to achieve obliviousness

I'm new to secure multi-party computation and ORAM. My question is quite simple. Is there a concrete example to explain the linear scan for an array with multiplexers to achieve obliviousness? I didn'...
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Difference between Non-Interactive Secure Multiparty Computation (NISMPC) and Fully Homomorphic Encryption (FHE)

Until recently, I only knew about SMPC* and FHE, but now I just encountered the term NISMPC. I was wondering what is their difference and what is their difference in their use cases? Sometimes in ...
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Data encryption or Blockchain in data sharing between *multiple* sources?

imagine several parties that own data, and some of them need to use data of other parties, but have only limited access rights to it. An example: Party #1 (pharmacy store) needs confirmation from ...
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What is the essential difference between Garbled Circuit and Oblivious Transfer?

According to the literature (https://en.wikipedia.org/wiki/Garbled_circuit), Oblivious Transfer allows a party A holding a function $f$ and a party B holding a index i to jointly compute the value $f(...
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Tools/libraries to protect private keys using shamir secret sharing / multi-party computation?

here is the scenario. I want to use the concept of shamir secret sharing (or other multi-party computation methods) to store my private key in the public-key encryption. For example, I use RSA to ...
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Anonymous PAKE using two party computation

Let's say client side has a secret password $\pi$. The server has a series of indices $0..n-1$ and a salt associated value $s_i$ for all $i \in \{0,n-1\}$ call it set $S=\{s_i | i \in \{0,n-1\}\}$ ...
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Does shared randomness between two cryptographic primitives complicate the hybrid argument for computational indistinguishability?

Let $(Enc, Dec)$ be an IND-CPA secure encryption scheme, where $Enc: \mathcal{K} \times \mathcal{M}_1 \rightarrow \mathcal{C}_1$, and $F: \mathcal{K} \times \mathcal{M}_2 \rightarrow \mathcal{C}_2$ be ...
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Tuples 2P secure multi-party computation against malicious adversaries algorithms

There are secure multi-party computation algorithms and implementations [1] for signing 2-party messages where the parties don't need to reveal their secrets. Can this algorithms be used for signing ...
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AES in binary-circuit-based 2PC

No matter AES with CBC or EBC etc, the inputs for AES i.e, plaintext, key, IV, are always provided by one party. In other words, there is no need for AES in a 2PC scenario since one party can already ...
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SHA-256 in binary-circuit-based MPC

For a binary-circuit-based MPC, the multiparty will provide its inputs to calculate the result, which indicated the function $f(x_1, x_2, \dots,x_n)$ needs to accept $2$ or more inputs. Why do there ...
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Why we need broadcast channel in the 3PC setting?

I am a MPC learner for privacy-preserving machine learning. Recently, I am reading this paper: FLASH: Fast and Robust Framework for Privacy-preserving Machine Learning. I am confused about the ...
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About simulating abort in multiple party computation

I am new to the simulated proof and am a little bit confused about the abort in the simulation. When the real-time protocol abort, I assume that the ideal process should also abort? Does this mean ...
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Securely sort lists of numbers from two parties

I am looking for ways to securely sort two lists of numbers. Yao's millionaire's problem considers each party with one secrete number and compare them securely. Are there papers on extension to this ...
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Are all parties for an MPC protocol needed?

For a lot of cryptographic applications, multi-party protocols are used. The idea is to create shares of a key/secret and give them to multiple parties. My question is: Do all parties have to ...
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Question about round complexity of secure multiple party computation based on secret sharing

I am reading Fast and Secure Three-party Computation: The Garbled Circuit Approach And in the introduction section it said that: the round complexity of these protocols is proportional to the ...
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Leaking information for giving the yao's garbled circuit's garbled output

I am currently reading the paper: Efficiency Tradeoffs for Malicious Two-Party Computation. The paper describes a $k$-leak model and gives an example that leaking 1 bit could turn Yao's garbled ...
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How could this scheme work?

When we use a secret sharing scheme we usually want to reconstruct the polynomial function $p(x)\in\mathbb{Z}_q[X]$ with the Lagrange interpolation method and then compute $s=p(0)=a_0$. However, the ...
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How can I use a secret sharing scheme when the secret is not a number but a statement?

I want to use a secret sharing scheme, where every player $i\in N$ has to share a pair of secrets $(l_i,\nu_{l_i})$, where $l_i$ is a unique code (positive integer) for every player, but $\nu_{l_i}$ ...
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Witness Recovery in SPDZ Offline Phase

I am currently reading SPDZ: https://eprint.iacr.org/2011/535.pdf. The MPC protocol uses an encryption scheme $\operatorname{Enc}_{\operatorname{pk}}(x,r)$ based on Brakerski, V. Vaikuntanathan (...
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How to define a cryptosystem when the encryption-decyrption scheme is based on Shamir's secret sharing scheme?

I would like to make a parallelism between Shamir's secret sharing scheme and how to define a cryptosystem where the encryption scheme is based on secret sharing. To begin with I do not know if there ...
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Privacy preserving functions vs secure multi-party computation

As we all know, secure multi-party computation allows us to run a certain computation/function on private inputs contributed by different parties (that do not necessarily trust each other). The ...
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Mathematical formulation for a cryptosystem

I will try to define easily the cryptographic system of this paper. The author designs a communication game for $N$ players. The private information of every player is denoted as $t_i\in T_i$ and ...
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Could someone explain the protocol of Yevgeniy Dodis, Shai Halevi, and Tal Rabin in details?

This is from the paper of Yevgeniy Dodis, Shai Halevi, and Tal Rabin Could anyone provide some help about understanding how the following protocol is executed? The game is played based on the sequel ...
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Is this a well defined sharing scheme to propose

A proposed secret sharing scheme: Suppose that $p:S\times Y\to X$, with $|Y|\geq|S|$ is a cipher where, $y\in Y$ is the key and $x\in X$ the code, $p$ is bijective, namely $(x,y)$ is associated with ...
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Secure multi-party computation made simple - questions

The scheme that I refer to is from this paper. A secret $s\in D$ is obtained by splitting s into a random sum. We have (actually linear) for any $k$ this $k$-out-of-$k$ secret-sharing scheme: Select $...
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Could you provide the proof of a secure multi - secret sharing scheme that fulfils the requirements of correctness and information-theoretic privacy?

Suppose that we have a multi-secret sharing scheme and let $I$ be the a set of agents. Say that $S$ is the space of the (uniform) random variables $s=(s_1,s_2,\cdots,s_I)\in S$ such that the share $...
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Could anybody help by applying a secure multiparty secret sharing scheme?

Suppose that we have a multi-secret sharing scheme as it is described in the literature Let there be $I$ agents and say that $S$ is the space of the (uniform) random variables $s=(s_1,s_2,\cdots,s_I)\...
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Is the Secret sharing scheme thresholds of variable of interest shared related with the entropy of the variable?

Is the $t$ out of $n$, namely $(t,n)$, threshold in the secret sharing scheme related to the entropy of the random variable that is shared according to the scheme? What changes in the secret sharing ...
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Could this scheme work for multiparty computation secret sharing?

Suppose that there are $5$ players and each of them learns a secret that is a coordinate of the random vector $s=(s_1,s_2,\cdots,s_5)$, such that $s$ is a uniformly distributed over the field $V$. ...
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Secret sharing scheme combined with probability theory results?

As a sequel of my previous post I am writing a new one with respect to the secret sharing scheme. I will only cite here the answer because I want to make a question on it. $\textbf{Answer:}$ To be ...
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How to design such a secure multiparty computation scheme with the players using a majority rule

Suppose that $y$ is a uniform random variable that is defined over the field (or group or abelian group) $Y$. Let us suppose that there are $N=\{1,2,\cdots,i\cdots,N\}$ agents and only one of them, ...
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Could this be a secure multiparty secret sharing scheme?

Suppose that $y$ is a uniform random variable that is defined over the field (or group or abelian group) $Y$. Let us suppose that there are $N=\{1,2,\cdots,i\cdots,N\}$ agents and only one of them, ...
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Secure multiparty scheme in key (splitting) distribution among the players

Suppose that we have a game with $I$ players and each of them has a private secret say $e_i$. Every player wants to share her secret with the rest of the players but in such a way that she will not be ...
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How can I enrich this mechanism of communication to become more efficient and secure?

Suppose that we have a Bayesian game, where $t_i\in T_i$ denotes the type of player $i$. Say that we have a communication game (communication equilibrium). The players do send each other an encrypted ...
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How to design such a protocol that the agents could replicate the mediator by themselves?

A problem in game theory is that of communication. Taking into account the classic approach of Myerson and Forges, the agents communicate each other, however indirectly, through a communication ...
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Generate asymmetric key pairs based on keywords such that any public key based on set containing the generating subset is valid

Let's assume we have a ton of users, and each user has a list of fruits they like - Those will be keywords. I want my users to be able to encode any data they store (Let's say, the location of their ...
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Could anyone provide any idea of such a protocol?

Could anybody provide the seminal paper and/or every specific manual in mathematics that describes a secure multiparty computation procedure, where the players will exchange encrypted messages (...
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Sharing information scheme of cryptography - operations in modular arithmetic

Taking into account my previous question here and the answer about the proposed encryption-decryption scheme. I am trying to understand how to make possible operations in modular arithmetic for a ...
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No-dealer secret sharing scheme that prevents anonymous collaboration to reconstruct the secret

Is there a no-dealer secret sharing scheme that allows a threshold $k$ of $n$ parties (where $k<n$) to collaborate to reconstruct a secret, but in such a way that none of those $k$ parties are able ...
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Why do we always assume that the functions that the protocols can replicate are of the form $f:\{0,1\}^*\to\{0,1\}^*$?

Taking into account the vast literature of secure multiparty computation and secret sharing, there is a specific assumption that is made for the calculation of a rule function. The latter function ...
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Can we encode with the set of $\{0,1\}$ and its Boolean operations any finite or infinite domain?

Can we encode with the set of $\{0,1\}$ and its Boolean operations any infinite domain that is subset of the real numbers $\mathbb{R}$ or the whole set of real numbers? For example can we encode the ...
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Efficient cheap talk communication in game theory

Are there any papers about efficient cheap talk communication, where the players achieve the equilibrium payoffs of a correlated strategy as in Aumann's seminal paper? Or in case no such paper exists, ...
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1 answer
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Can anybody explain the proof of Rabin and Ben-or of secure multiparty computation?

Can anybody explain the proof of Rabin and Ben-or of secure multiparty computation? The idea is that every player $i$, of $N<+\infty$ players, holds a secret say $s_i$. All of them want to share ...
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Rational secure multiparty computation with permuatation secret sharing scheme?

Taking a look in this economic paper they use cryptographic tools to implement correletaed equilibria in the case of two plaeyrs. They use permutations for the exchange of information between the ...
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Secure protocols by implementing cheap talk instead on a centralized mediator to compute any function $f(s_1,...,s_n) = (y_1,...,y_n)$?

Based on this paper a protocol is secure if and only if it satisfies secrecy and resiliency. Most of the papers in ecnomic and computer since deal with the following problem. They consider the case ...
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For unequal set sizes in PSI: why should the party with fewer elements use cuckoo hash rather than simple hash?

Most PSI papers usually use hash-to-bin to improve the number of comparsons. For unequal set sizes in 2PSI, I have read CCS17, which designs a PSI protocol for unequal size. The party with fewer ...
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