Paper 2023/1879

A Multiparty Commutative Hashing Protocol based on the Discrete Logarithm Problem

Abstract

Let $\mathcal{X}$ and $\mathcal{Y}$ be two sets and suppose that a set of participants $P=\{P_1,P_2,\dots ,P_n\}$ would like to calculate the keyed hash value of some message $m\in \mathcal{X}$ known to a single participant in $P$ called the data owner. Also, suppose that each participant $P_i$ knows a secret value $x_i\in \mathcal{X}$. In this paper, we will propose a protocol that enables the participants in this setup to calculate the value $y=H(m,x_1,x_2,\dots ,x_n)$ of a hash function $H:{\mathcal{X}}^{n+1}\to \mathcal{Y}$ such that: - The function $$ is a one-way function. - Participants in $$ cannot obtain $$. - Participants other than the data owner cannot obtain $$. - The hash value $$ remains the same regardless the order of the secret $$ values.