International Association
for Cryptologic Research

The Polynomial Modular Number System (PMNS) is a non-positional number system for modular arithmetic. A PMNS is defined by a tuple $(p, n, \gamma, \rho, E)$, where $p$, $n$, $\gamma$ and $\rho$ are positive non-zero integers and $E\in\mathbb{Z}_{n}[X]$ is a monic polynomial such that $E(\gamma) \equiv 0 \pmod p$. The PMNS is a redundant number system. In~\cite{rando-pmns-arith26}, Didier et al. used this redundancy property to randomise the data during the Elliptic Curve Scalar Multiplication (ECSM). In this paper, we refine the results on redundancy and propose several new results on PMNS. More precisely, we study a generalisation of the Montgomery-like internal reduction method proposed by Negre and Plantard, along with some improvements on parameter bounds for smaller memory cost to represent elements in this system. We also show how to perform equality test in the PMNS.