One of the primary new standards for surviving quantum computers would act as a total Denial-of-Service attack on the world payment systems.
Financial infrastructure like Australia's New Payments Platform needs to upgrade to post-quantum signatures to stay secure. Simulations show that the SPHINCS+ signature method is so resource-heavy that it would crash the entire network. While other standards work fine, this one particular choice would make real-time payments impossible. This research identifies a concrete, high-stakes failure point in our plan to secure the world money from quantum hackers. It forces a change in how we select the cryptographic tools that will protect our future economy.
Post-Quantum Cryptography Migration in Australian Real-Time Payment Infrastructure: A Monte Carlo Simulation Study of the New Payments Platform
arXiv · 2605.02276
Australia's New Payments Platform (NPP) processes 5.2 million real-time transactions per day under a 2,000 ms SLA. With cryptographically relevant quantum computers projected by 2030-2035 and the Harvest Now, Decrypt Later (HNDL) threat active, this paper presents a Monte Carlo simulation study of NIST FIPS 204/205/206 signature standards (ML-DSA, SLH-DSA/SPHINCS+, Falcon) in Australian payment infrastructure, jointly modelling M/M/c queue saturation, GEV tail bounds, and HNDL actuarial exposure