  Physical Unclonable Functions (PUFs) are hardware devices with the assumption
of possessing inherent non-clonable physical randomness which leads to unique
pairs of inputs and outputs that provide a secure fingerprint for cryptographic
protocols like authentication. In the case of quantum PUFs (QPUFs), the
input-output pairs consist of quantum states instead of classical bitstrings,
offering advantages over classical PUFs (CPUFs) such as challenge reusability
via public channels and non-reliance over any trusted party due to the
no-cloning theorem. In recent literature, a generalized mathematical framework
for studying QPUFs was developed, which paved the way for having QPUF models
with provable security. It was proved that \emph{existential unforgeability}
against Quantum Polynomial Time (QPT) adversaries cannot be achieved by any
random unitary QPUF. Since measurements are non-unitary quantum processes, we
define a QPUF based on random von Neumann measurements. We prove that such a
QPUF is existentially unforgeable. Thus, we introduce the first model in
existing literature that depicts such a high level of provable security. We
also prove that the Quantum Phase Estimation (QPE) protocol applied on a Haar
random unitary serves as an approximate implementation for this kind of QPUF as
it approximates a von Neumann measurement on the eigenbasis of the unitary.
