# 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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### Share Conversion between Different Finite Fields

Let us have any linear secret sharing scheme (LSSS) that works on some field $Z_{p}$, where p is some prime or a power of a prime e.g., Shamir Secret Sharing, Additive secret Sharing. The problem at ...
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### Distributed generation of random integers with prescribed sum

While reading this document I came across the following problem. Assume you have $n$ clients. The clients need to generate random integers in $\mathbb{Z}_p$, say $T_i$ for $i \in \{1, \ldots, n\}$, ...
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### Multi-party computation with untrusted nodes?

Let $L = [b_1, \dots, b_k]$ be a list of blocks of a file. I want to compute the function $f = h(g(b_1), \dots, g(b_k))$ on $N$ untrusted nodes such that: Anyone can be reasonable convinced (with ...
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### An MPC protocol from Elgamal is a good solution a homomorphic multiplication?

I want to compute a multiplication between many secret values and then distribute the result to everyone involved. For this, I thought about an MPC protocol built from Threshold Homomorphic Elgamal. ...
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### How can I implement decryption for NTRU homomorphic encryption scheme?

I have come across this paper On-the-fly multiparty computation via on-the-cloud Multikey from Fully Homomorphic Encryption by Lopez-Alt et al., where authors describe a NTRU-based homomorphic ...
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### How about a homomorphic integer sorting in a MPC context?

I want to implement the ATV-FHE scheme as described by Adriana López-Alt, Eran Tromer, Vinod Vaikuntanathan: On-the-Fly Multiparty Computation on the Cloud via Multikey Fully Homomorphic Encryption (...
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### Are there secure MPC schemes that support uneven load balancing between the parties?

In a scenario in which some of the parties have more data / compute power / trust reputation (or other meaningful properties) than other parties - are there known methods to do secure multiparty ...
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### Is there any OPRF (oblibivious pseudo random random functions) between one receiver (1 input) and n senders (n inputs)? any references to read?

I am looking for some references for multi-party / distributed Oblivious pseudorandom Functions. I found two party OPRF protocols between a sender $S$ and a receiver $R$ for securely computing a ...
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### Product of secrets in multi-secret sharing schemes (aka packed secret sharing schemes)

The question is related to the multi-secret sharing scheme described in the following paper: [FY92] Matthew K. Franklin, Moti Yung: Communication Complexity of Secure Computation (Extended Abstract). ...
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### RLWE like problem

Assume we have the polynomial space $R_q$ defined as $R_q = Z_q/(X^n + 1)$. Additionally, we define the error distribution $\chi$ as a discrete centred Gaussian bounded by $B$. Let $s \gets R_q$ be a ...
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### Trade-offs for more parties in PICNIC multi-computation

In the PICNIC post-quantum signature scheme, a zero-knowledge proof of the secret key for a symmetric encryption is produced by implementing the encryption as a Yao garbled circuit of a three-party ...
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### Authenticated sharing in MASCOT protocol

I am studying MASCOT protocol for multiparty computation and I am stuck in the comprehension of the authentication protocol $\Pi_{[[ \cdot ]]}$ and its security proof. Supposing the initialize phase ...
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### Why should the smudge noise be used?

Consider a threshold FHE scheme based on RLWE like this: Refer to this paper $\textbf{Initialization:}$ Every party generates his own secret key $s_i$, then uses the common polynomial $a$ to generate ...
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### Secure Protocol

How to show there is no secure protocol to compute OR? I need to know the mathematical proof of this statement. I am understanding this statement using the matrix representation of $f(x,y)$ but unable ...
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### Can we use a pseudorandom function in both models of a simulation based proof?

Assume in the real model a party blinds a fixed element $b$ as: $v_i=r_i\cdot b$, where $r_i$ is a output of pseudorandom function. So we give $v_i$ to a semi-honest adversary. Now we want to sketch ...
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### Why do authors execute a leakage resilient election protocol inside a leak-free phase?

In the paper "Multiparty Computation Secure Against Continual Memory Leakage", on page 1241 (that's page 7 of the PDF) under section 2.3, the authors discuss "The Election Protocol" that they use to ...
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### Can you clarify the proof that secure LR-two party protocols do not exist?

In the paper “Multiparty Computation Secure Against Continual Memory Leakage” on pg. 1237, the footnote #1 discuss why it is not possible to construct a leakage resilient two-party protocol. But I'm ...
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### Does using a verifiable secret sharing scheme ensure robustness of a protocol if it is secure under the semi-honest adversarial model

Consider a protocol $\pi$ which uses a linear secret sharing scheme like that of Shamir secret sharing. Further assume that the protocol $\pi$ has been proven to be secure (correctness and privacy) ...
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### Proving for a single input vs several inputs. Is there any difference?

I am working on a new protocol for pattern matching. While defining the ideal functionality, it is possible to say: Alice sends $p$ and Bob sends $T$ to the ideal functionality. i.e. searching for ...
In the paper "Multiparty Computation Secure Against Continual Memory Leakage" on pg. 1239 the footnote at the bottom points out the difference between $joint$ leakage and $disjoint$ leakage. The ...